RFC 2828

Internet Security Glossary

📅 published May 2000, from ietf

(part 1 of 39, more on the way!) 💖

Internet Security Glossary ✨

okay bestie, this is RFC 2828, and it's called Internet Security Glossary 🎀 R. Shirey from GTE / BBN Technologies wrote it. It's an Informational doc (FYI 36 🦋), and it came out in May 2000. Its header doesn't list anything it obsoletes or updates.

Status of this Memo 📝

This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.

Copyright Notice ©️

Abstract 🌸

okay so this Glossary is 191 pages of definitions plus 13 pages of references 📚 It gives you abbreviations, explanations, and recommendations for using information system security terminology. The big goal is to make writing about Internet security easier to understand, especially Internet Standards documents (ISDs). To avoid confusion, ISDs should use the same term or definition whenever the same concept comes up. For international understanding, ISDs should use terms in their plainest, dictionary sense. ISDs should use terms that are already established in standards documents and other well-founded publications, and they should avoid private or newly made-up terms. ISDs should also avoid terms that are proprietary or that favor a particular vendor, and terms that create a bias toward one security technology or mechanism over other, competing techniques that already exist or might be developed in the future. no bias, no drama 💅

Table of Contents 🧚

   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2. Explanation of Paragraph Markings  . . . . . . . . . . . . . .   4
      2.1 Recommended Terms with an Internet Basis ("I") . . . . . .   4
      2.2 Recommended Terms with a Non-Internet Basis ("N")  . . . .   5
      2.3 Other Definitions ("O")  . . . . . . . . . . . . . . . . .   5
      2.4 Deprecated Terms, Definitions, and Uses ("D")  . . . . . .   6
      2.5 Commentary and Additional Guidance ("C") . . . . . . . . .   6
   3. Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 197
   5. Security Considerations  . . . . . . . . . . . . . . . . . . . 211
   6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 211
   7. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 211
   8. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 212

1. Introduction ✨

okay so this Glossary gives you an internally consistent, complementary set of abbreviations, definitions, explanations, and recommendations for using terminology related to information system security 🧚 The whole point is to make Internet Standards documents (ISDs) easier to understand. That means RFCs, Internet-Drafts, and other material produced as part of the Internet Standards Process [R2026]. It also helps with all the other Internet material too 💖 Some non-security terms are included so the Glossary can stand on its own, but bigger lists of networking terms are available elsewhere [R1208, R1983].

Some glossaries (e.g., [Raym]) list terms that could be applied to Internet security but aren't listed here. Those terms were left out because they aren't appropriate for ISDs.

This Glossary marks terms and definitions as either endorsed or deprecated for use in ISDs, but the Glossary itself is not an Internet standard 🫶 The key words "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are meant to be read the same way as in an Internet Standard [R2119]. The catch is that this guidance is only the recommendations of this author. The Glossary also explains the reasons behind its recommendations, especially for the SHOULD NOTs, so readers can judge for themselves whether to follow them. main character energy: thinking for yourself 🦋

This Glossary supports the goals of the Internet Standards Process:

Clear, Concise, and Easily Understood Documentation

This Glossary wants security-related content of ISDs to be easier to understand. That means clear wording, and a set of security terms and definitions that are consistent and self-supporting. The terminology also needs to be uniform across all ISDs, so the same term or definition is used wherever the same concept shows up. Fixing existing ISDs doesn't have to happen right away, but it's worth correcting and standardizing the terminology when new versions come out during normal standards development and evolution 📚

Technical Excellence

Just as Internet Standard (STD) protocols should operate effectively, ISDs should use terminology accurately, precisely, and unambiguously so Internet Standards can be implemented correctly 💅

Prior Implementation and Testing

Just as STD protocols need demonstrated experience and stability before adoption, ISDs need to use well-established language 🍓 Using terms in their plainest, dictionary sense (when appropriate) helps everyone around the world understand them. ISDs need to avoid private, made-up terms in place of generally-accepted terms from standards and other publications. They also need to avoid new definitions that conflict with established ones. And they need to avoid "cute" synonyms (e.g., see: Green Book), because no matter how popular a nickname is in one community, it can cause confusion in another 🙈

Openness, Fairness, and Timeliness

ISDs need to avoid terms that are proprietary or that favor a particular vendor, and terms that create a bias toward one security technology or mechanism over other, competing techniques that already exist or might be developed in the future. The terminology across all ISDs needs to stay flexible and adaptable as Internet security art evolves 🌈

2. Explanation of Paragraph Markings 🔥

Section 3 marks terms and definitions as follows:

Capitalization: Only terms that are proper nouns are capitalized.
Paragraph Marking: Definitions and explanations are stated in paragraphs that are marked as follows:
- "I" identifies a RECOMMENDED Internet definition.
- "N" identifies a RECOMMENDED non-Internet definition.
- "O" identifies a definition that is not recommended as the first choice for Internet documents but is something that authors of Internet documents need to know.
- "D" identifies a term or definition that SHOULD NOT be used in Internet documents.
- "C" identifies commentary or additional usage guidance.

The rest of Section 2 further explains these five markings 🎀

2.1 Recommended Terms with an Internet Basis ("I")

The paragraph marking "I" (as opposed to "O") indicates a definition that SHOULD be the first choice for use in ISDs. Most terms and definitions of this type MAY be used in ISDs. Some "I" definitions come with a "D" paragraph that recommends against using the term, though. Some "I" definitions are also preceded by a contextual usage limitation (e.g., see: certification), and ISDs should not use the term and definition outside that context 🙈

An "I" (as opposed to an "N") also means the definition has an Internet basis. Either the Internet Standards Process is authoritative for the term, or the term is generic enough that this Glossary can freely state a definition without contradicting a non-Internet authority (e.g., see: attack) 🦋

Lots of terms with "I" definitions are proper nouns (e.g., see: Internet Protocol). For these, the "I" definition only gives basic information, and the authoritative definition lives somewhere else 💜

For a proper noun identified as an "Internet protocol", check the current edition of "Internet Official Protocol Standards" (STD 1) for the protocol's standardization state and status 🌸

2.2 Recommended Terms with a Non-Internet Basis ("N")

The paragraph marking "N" (as opposed to "O") indicates a definition that SHOULD be the first choice for the term, if the term is used at all in Internet documents. Terms and definitions of this type MAY be used in Internet documents (e.g., see: X.509 public-key certificate) ✨

An "N" (as opposed to an "I") also means the definition has a non-Internet basis or origin. Lots of these definitions come with a contextual usage limitation, and this Glossary's endorsement doesn't apply outside that context. Some contexts are rarely, if ever, expected to show up in an Internet document (e.g., see: baggage). In those cases, the listing exists so Internet authors know about the non-Internet usage and can avoid conflicts with non-Internet documents 👑

Lots of terms with "N" definitions are proper nouns (e.g., see: Computer Security Objects Register). For these, the "N" definition only gives basic information, and the authoritative definition lives somewhere else 🧚

2.3 Other Definitions ("O")

The paragraph marking "O" indicates a definition that has a non-Internet basis, but the definition SHOULD NOT be used in ISDs except where the term is specifically identified as non-Internet 💅

For example, an ISD might mention "BCA" (see: brand certification authority) or "baggage" to illustrate some concept. In that case, the document should specifically say SET(trademark) BCA or SET(trademark) baggage and include the definition of the term 🎀

For some terms that have a definition published by a non-Internet authority, this Glossary marks the definition "N" and recommends its use in Internet documents. The authorities can be government (see: object reuse), industry (see: Secure Data Exchange), national (see: Data Encryption Standard), or international (see: data confidentiality) 🌈 In other cases, the non-Internet definition of a term is inadequate or inappropriate for ISDs. It might be narrow or outdated, or it might need clarification by using more careful or more explanatory wording built from other terms defined in this Glossary. In those cases, this Glossary marks the term "O" and provides an "I" definition (or sometimes a different "N" definition). That one comes first and supersedes the definition marked "O" 🔥

In most cases where this Glossary gives a definition to supersede one from a non-Internet standard, the substitute is meant to subsume the meaning of the superseded "O" definition and not conflict with it. Take the term "security service". Its "O" definition only deals with communication services provided by layers in the OSI model, which isn't enough for the full range of ISD usage. The "I" definition works in more situations and for more kinds of service. The "O" definition is still included here, though, so ISD authors know the context where the term is used more narrowly 💜

When making substitutions, this Glossary tries to use understandable English that doesn't contradict any non-Internet authority. Still, terminology differs between the standards of the American Bar Association, OSI, SET, the U.S. Department of Defense, and other authorities. This Glossary probably isn't exactly aligned with all of them 🫶

2.4 Deprecated Terms, Definitions, and Uses ("D") 🙈

Okay so, if this Glossary says a term or definition SHOULD NOT be used in ISDs, then either the definition gets the paragraph marking "D", or the restriction shows up in a "D" paragraph right after the term or definition. 💅

2.5 Commentary and Additional Guidance ("C") ✨

The "C" marking is for the advisory and tutorial bits 🎀. This text MAY be reused in other Internet documents. It's not meant to be authoritative. It's here to clarify the definitions and make this Glossary a tutorial that Internet security newbies can actually learn from 🧚

3. Definitions 💖

Note: Each acronym or other abbreviation (except items of common English usage, such as "e.g.", "etc.", "i.e.", "vol.", "pp.", "U.S.") that is used in this Glossary, either in a definition or as a subpart of a defined term, is also defined in this Glossary. 🫶

3DES See: triple DES.

*-property (N) (Pronounced "star property".) See: "confinement property" under Bell-LaPadula Model. 🎀

ABA Guidelines (N) "American Bar Association (ABA) Digital Signature Guidelines" [ABA], a framework of legal principles for using digital signatures and digital certificates in electronic commerce. 💼

Abstract Syntax Notation One (ASN.1) (N) A standard for describing data objects. [X680]

(C) Okay, so OSI standards use ASN.1 to specify data formats for protocols 🤓 OSI defines functionality in layers. Information objects at higher layers are abstractly defined to be implemented with objects at lower layers. A higher layer may define transfers of abstract objects between computers, and a lower layer may define transfers concretely as strings of bits. You need syntax to define abstract objects, and encoding rules to transform between abstract objects and bit strings. (See: Basic Encoding Rules.)

(C) In ASN.1, formal names are written without spaces, and separate words in a name are indicated by capitalizing the first letter of each word except the first word. For example, the name of a CRL is "certificateRevocationList" ✨

ACC See: access control center.

access (I) The ability and means to communicate with or otherwise interact with a system in order to use system resources to either handle information or gain knowledge of the information the system contains. 👀

(O) "A specific type of interaction between a subject and an object that results in the flow of information from one to the other." [NCS04]

(C) In this Glossary, "access" is meant to cover any ability to communicate with a system, including one-way communication in either direction. In actual practice, though, entities outside a security perimeter that can receive output from the system but cannot provide input or otherwise directly interact with the system might be treated as not having "access" and, therefore, be exempt from security policy requirements, such as the need for a security clearance. 🙈

access control (I) Protection of system resources against unauthorized access. It's a process by which use of system resources is regulated according to a security policy and is permitted by only authorized entities (users, programs, processes, or other systems) according to that policy. (See: access, access control service.) 🔐

(O) "The prevention of unauthorized use of a resource, including the prevention of use of a resource in an unauthorized manner." [I7498 Part 2]

access control center (ACC) (I) A computer containing a database with entries that define a security policy for an access control service. 🖥️

(C) An ACC is sometimes used alongside a key center to implement access control in a key distribution system for symmetric cryptography. 🗝️

access control list (ACL) (I) A mechanism that implements access control for a system resource by listing out the identities of the system entities that are permitted to access the resource. (See: capability.) 📜

access control service (I) A security service that protects against a system entity using a system resource in a way not authorized by the system's security policy. Basically, it's protection of system resources against unauthorized access. (See: access control, discretionary access control, identity-based security policy, mandatory access control, rule-based security policy.) 💅

(C) This service includes protecting against use of a resource in an unauthorized manner by an entity that is authorized to use the resource in some other manner. The two basic mechanisms for implementing this service are ACLs and tickets. 🎟️

access mode (I) A distinct type of data processing operation (e.g., read, write, append, or execute) that a subject can potentially perform on an object in a computer system. 📖

accountability (I) The property of a system (including all of its system resources) that makes sure the actions of a system entity can be traced uniquely to that entity, which can be held responsible for its actions. (See: audit service.) 🧾

accredit / accreditation (I) An administrative declaration by a designated authority that an information system is approved to operate in a particular security configuration with a prescribed set of safeguards. [FP102] (See: certification.) ✅

(C) An accreditation is usually based on a technical certification of the system's security mechanisms. The terms "certification" and "accreditation" get used more in the U.S. Department of Defense and other government agencies than in commercial organizations. Still, the concepts apply anywhere managers have to deal with and accept responsibility for security risks. The American Bar Association is developing accreditation criteria for CAs. ⚖️

ACL See: access control list.

acquirer (N) SET usage: "The financial institution that establishes an account with a merchant and processes payment card authorizations and payments." [SET1] 💳

(O) "The institution (or its agent) that acquires from the card acceptor the financial data relating to the transaction and initiates that data into an interchange system." [SET2]

active attack See: (secondary definition under) attack.

active wiretapping See: (secondary definition under) wiretapping.

add-on security (I) "The retrofitting of protection mechanisms, implemented by hardware or software, after the [automatic data processing] system has become operational." [FP039] 🔧

administrative security (I) Management procedures and constraints to prevent unauthorized access to a system. (See: security architecture.) 📋

(O) "The management constraints, operational procedures, accountability procedures, and supplemental controls established to provide an acceptable level of protection for sensitive data." [FP039]

Advanced Encryption Standard (AES) (N) A future FIPS publication being developed by NIST to succeed DES. It's intended to specify an unclassified, publicly-disclosed, symmetric encryption algorithm that's available royalty-free worldwide. 🌍

adversary (I) An entity that attacks, or is a threat to, a system. 😈

aggregation (I) A circumstance in which a collection of information items is required to be classified at a higher security level than any of the individual items that make it up. 🧩

AH See: Authentication Header

algorithm (I) A finite set of step-by-step instructions for a problem-solving or computation procedure, especially one that can be implemented by a computer. (See: cryptographic algorithm.) 🧮

alias (I) A name that an entity uses in place of its real name, usually for the purpose of either anonymity or deception. 🎭

American National Standards Institute (ANSI) (N) A private, not-for-profit association of users, manufacturers, and other organizations that administers U.S. private sector voluntary standards. 🏛️

(C) ANSI is the sole U.S. representative to the two major non-treaty international standards organizations: ISO and, via the U.S. National Committee (USNC), the International Electrotechnical Commission (IEC). 🌐

anonymous (I) The condition of having a name that is unknown or concealed. (See: anonymous login.) 🫥

(C) An application may need security services that keep users or other system entities anonymous, maybe to protect their privacy or hide them from attack. To hide an entity's real name, an alias may be used. For example, a financial institution may assign an account number. Parties to a transaction can stay relatively anonymous but still accept the transaction as legitimate. Observers of the transaction can't easily figure out the real names of the parties, but an authorized third party may be able to map an alias to a real name, such as by presenting the institution with a court order. In other applications, anonymous entities may be completely untraceable. 👻

anonymous login (I) An access control feature (or, rather, an access control weakness) in many Internet hosts that lets users get access to general-purpose or public services and resources on a host (such as letting any user transfer data using File Transfer Protocol) without a pre-established, user-specific account (i.e., user name and secret password). 🚪

(C) This feature exposes a system to more threats than when all the users are known, pre-registered entities that are individually accountable for their actions. A user logs in using a special, publicly known user name (e.g., "anonymous", "guest", or "ftp"). To use the public login name, the user doesn't have to know a secret password and may not have to input anything at all except the name. In other cases, to finish the normal sequence of steps in a login protocol, the system may require the user to input a matching, publicly known password (such as "anonymous") or may ask the user for an e-mail address or some other arbitrary character string. 🙈

APOP See: POP3 APOP.

archive (I) (1.) Noun: A collection of data that is stored for a relatively long period of time for historical and other purposes, such as to support audit service, availability service, or system integrity service. (See: backup.) (2.) Verb: To store data in such a way. (See: back up.) 🗄️

(C) A digital signature may need to be verified many years after the signing happens. The CA (the one that issued the certificate containing the public key needed to verify that signature) may not stay in operation that long. So every CA needs to provide for long-term storage of the information needed to verify the signatures of those it issues certificates to. 🕰️

ARPANET 🛰️

(N) Advanced Research Projects Agency Network. This was a pioneering packet-switched network built in the early 1970s under contract to the U.S. Government, and it basically led to today's Internet 🌐. It was decommissioned in June 1990, so iconic origin story, honestly.

ASN.1 💅

See: Abstract Syntax Notation One.

association 🤝

(I) Okay, this is a cooperative relationship between system entities, usually set up so they can pass information between each other. It's teamwork, bestie 🫶 (See: security association.)

assurance 🔒

(I) (1.) This is an attribute of an information system that gives you solid grounds to be confident the system really enforces its system security policy. (2.) It's also a procedure that makes sure a system gets developed and run the way its security policy intends. Main character energy for security, no cap ✨

assurance level 📊

(I) Evaluation usage: This is a specific level on a hierarchical scale, and each step means you're more and more confident that a target of evaluation fully meets the requirements. (E.g., see: TCSEC.)

asymmetric cryptography 🗝️

(I) A modern branch of cryptography (popularly known as "public-key cryptography") where the algorithms use a pair of keys, a public key and a private key, and each one gets used for a different step of the algorithm. (See: key pair.)

(C) Okay, asymmetric algorithms are lowkey iconic for key management compared to equally strong symmetric ones. First, only the owner needs to know one key of the pair, so it's way easier to keep secret 🤫. Second, the other key is shared with every entity that uses the algorithm, but it doesn't have to be kept secret from entities that don't use it, so distributing keys gets easier too 💖.

(C) For encryption: In an asymmetric encryption algorithm (e.g., see: RSA), when Alice wants to keep data she sends to Bob confidential, she encrypts it with a public key that Bob gave her. Only Bob has the matching private key needed to decrypt it. Secret delivered 📬

(C) For signature: In an asymmetric digital signature algorithm (e.g., see: DSA), when Alice wants to make sure data she sends to Bob hasn't been messed with, or wants to prove who it came from, she signs the data with her private key (so, creates a digital signature based on the data). To verify it, Bob uses Alice's matching public key, which she already shared 🖊️.

(C) For key agreement: In an asymmetric key agreement algorithm (e.g., see: Diffie-Hellman), Alice and Bob each send their own public key to the other. Then each of them uses their own private key plus the other's public key to compute the new key value. It's like a secret handshake, and it's giving magic 🪄.

attack 🎯

(I) An assault on system security that comes from an intelligent threat, meaning a deliberate act (especially a method or technique) trying to dodge security services and break a system's security policy. (See: penetration, violation, vulnerability.)

Active vs. passive: An "active attack" tries to change system resources or mess with how they run. A "passive attack" tries to learn or use information from the system without touching the resources themselves. (E.g., see: wiretapping.) Eavesdropping vs. tampering, bestie 👀
Insider vs. outsider: An "inside attack" comes from an entity inside the security perimeter (an "insider"). That's someone allowed to access the resources who uses them in a way the people who granted access never approved 😬. An "outside attack" comes from outside the perimeter, from an unauthorized or illegitimate user (an "outsider"). On the Internet, outside attackers can be anything from amateur pranksters to organized criminals, international terrorists, and hostile governments. Yikes 💀

+ - - - - - - - - - - - - +  + - - - - +  + - - - - - - - - - - -+
| An Attack:              |  |Counter- |  | A System Resource:   |
| i.e., A Threat Action   |  | measure |  | Target of the Attack |
| +----------+            |  |         |  | +-----------------+  |
| | Attacker |<==================||<=========                 |  |
| |   i.e.,  |   Passive  |  |         |  | |  Vulnerability  |  |
| | A Threat |<=================>||<========>                 |  |
| |  Agent   |  or Active |  |         |  | +-------|||-------+  |
| +----------+   Attack   |  |         |  |         VVV          |
|                         |  |         |  | Threat Consequences  |
+ - - - - - - - - - - - - +  + - - - - +  + - - - - - - - - - - -+

attribute authority 🏛️

(I) A CA that issues attribute certificates. ✨

(O) "An authority, trusted by the verifier to delegate privilege, which issues attribute certificates." [FPDAM]

attribute certificate 📜

(I) A digital certificate that binds a set of descriptive data items, other than a public key, either directly to a subject name or to the identifier of another certificate that is a public-key certificate. [X509]

(O) "A set of attributes of a user together with some other information, rendered unforgeable by the digital signature created using the private key of the CA which issued it." [X509]

(O) "A data structure that includes some attribute values and identification information about the owner of the attribute certificate, all digitally signed by an Attribute Authority. This authority's signature serves as the guarantee of the binding between the attributes and their owner." [FPDAM]

(C) So a public-key certificate ties a subject name to a public key value, plus the info needed to do certain crypto functions. Other attributes of a subject, like a security clearance, can be certified in a separate kind of digital certificate called an attribute certificate. A subject can have several attribute certificates tied to its name or to each of its public-key certificates 🎀.

Different lifetimes: When an attribute binding lasts shorter than the related public-key certificate, or when you'd rather not have to revoke a subject's public key just to revoke one attribute 🕰️.
Different authorities: When the authority responsible for the attributes is different from the one that issues the subject's public-key certificate. (There is no requirement that an attribute certificate be issued by the same CA that issued the associated public-key certificate.) Different people, different jobs 💁‍♀️

audit service 📋

(I) A security service that records the info needed to establish accountability for system events and for the actions of system entities that cause them. (See: security audit.)

audit trail 🐾

See: security audit trail.

AUTH 🔑

See: POP3 AUTH.

authentic signature ✍️

(I) A signature (especially a digital signature) you can trust because it can be verified. (See: validate vs. verify.)

authenticate 🕵️‍♀️

(I) Verify (meaning, establish the truth of) an identity that a system entity claims, either by itself or for it. (See: authentication.)

(D) In everyday English, "authenticate" usually means "to prove genuine" (like an art expert authenticating a Michelangelo painting). But the recommended definition has a much narrower meaning, bestie. For example, to be precise, an ISD SHOULD NOT say "the host authenticates each received datagram". Instead, the ISD SHOULD say "the host authenticates the origin of each received datagram". Usually we can also add "and verifies the datagram's integrity", since that's typically implied 🧠. (See: ("relationship between data integrity service and authentication services" under) data integrity service.)

(D) ISDs SHOULD NOT talk about authenticating a digital signature or digital certificate. Instead, we "sign" and then "verify" digital signatures, and we "issue" and then "validate" digital certificates. (See: validate vs. verify.) Vocab check passed ✅

authentication 🪪

(I) The process of verifying an identity that a system entity claims, either by itself or for it. (See: authenticate, authentication exchange, authentication information, credential, data origin authentication, peer entity authentication.)

Identification step: Presenting an identifier to the security system. (Identifiers should be assigned carefully, because authenticated identities are the basis for other security services, such as access control service.) Name tag, but make it serious 🏷️
Verification step: Presenting or generating authentication information that backs up the binding between the entity and the identifier. (See: verification.) Receipts, please 🧾

authentication code 🚫

(D) ISDs SHOULD NOT use this term as a synonym for any form of checksum, whether cryptographic or not. Honestly, "authentication" is misleading here, since the mechanism usually serves a data integrity function instead of an authentication one. And "code" is misleading too, because it suggests encoding or encryption is involved, or that it's a piece of software. Not it 🙅‍♀️ (See: message authentication code.)

authentication exchange 🗣️

(I) A mechanism for verifying an entity's identity through information exchange.

(O) "A mechanism intended to ensure the identity of an entity by means of information exchange." [I7498 Part 2]

Authentication Header (AH) 🧢

(I) An Internet IPsec protocol [R2402] designed to provide connectionless data integrity service and data origin authentication service for IP datagrams, and (optionally) to provide protection against replay attacks. Protect your packets, periodt 💅

(C) Replay protection may be selected by the receiver when a security association is established. AH authenticates upper-layer protocol data units and as much of the IP header as possible. But some IP header fields may change in transit, and the value of those fields may not be predictable by the sender when the packet arrives at the receiver. So those values can't be protected end-to-end by AH, and protection of the IP header by AH is only partial when such fields are present 🥲.

(C) AH may be used alone, or together with the IPsec ESP protocol, or in a nested fashion with tunneling. Security services can be provided between a pair of communicating hosts, between a pair of communicating security gateways, or between a host and a gateway. ESP can provide the same security services as AH, and ESP can also provide data confidentiality service. The main difference between the authentication services of ESP and AH is how much they cover: ESP does not protect IP header fields unless they are encapsulated by AH. It's the coverage gap, bestie 🕳️

authentication information 🔐

(I) Information used to verify an identity claimed by or for an entity. (See: authentication, credential.)

(C) okay so authentication info can exist as, or be derived from, one of these three things, and I'm obsessed with how clean the list is 🫶

Something the entity knows. (See: password).
Something the entity possesses. (See: token.)
Something the entity is. (See: biometric authentication.)

authentication service 🔐 (I) This is a security service that checks that an identity someone claims (by them or for them) is actually legit. (See: authentication.)

(C) In a network there are two main flavors: data origin authentication service and peer entity authentication service. Both are giving protection, just in different ways ✨

authenticity 💅 (I) This is the property of something being genuine, able to be verified, and trustworthy. Iconic. (See: authenticate, authentication, validate vs. verify)

authority 👑 (D) "An entity, responsible for the issuance of certificates." [FPDAM]

(C) ISDs SHOULD NOT use this term as a synonym for AA, CA, RA, ORA, or similar terms, because it can get confusing 🙈 Instead, spell out the full term the first time, and if you need to shorten things later, use the abbreviation style defined in this Glossary.

(C) ISDs SHOULD NOT use this definition for any PKI entity, because it's ambiguous about whether the entity actually issues certificates (like an attribute authority or certification authority) or just handles stuff before or after signing (like a registration authority). Not it. (See: issue.)

authority certificate 🎀 (D) "A certificate issued to an authority (e.g. either to a certification authority or to an attribute authority)." [FPDAM] (See: authority.)

(C) ISDs SHOULD NOT use this term or definition, because they're vague about which specific types of PKI entities they're talking about 💀

authority revocation list (ARL) 🚫 (I) This is a data structure that lists digital certificates issued to CAs that got invalidated by their issuer before they were scheduled to expire. (See: certificate expiration, X.509 authority revocation list.)

(O) "A revocation list containing a list of public-key certificates issued to authorities, which are no longer considered valid by the certificate issuer." [FPDAM]

authorization and authorize 🔑 (I) Okay, three little parts here. (1.) An "authorization" is a right or permission granted to a system entity so it can access a system resource. (2.) An "authorization process" is the procedure for handing out those rights. (3.) To "authorize" means to actually grant that right or permission. (See: privilege.)

(O) SET usage: "The process by which a properly appointed person or persons grants permission to perform some action on behalf of an organization. This process assesses transaction risk, confirms that a given transaction does not raise the account holder's debt above the account's credit limit, and reserves the specified amount of credit. (When a merchant obtains authorization, payment for the authorized amount is guaranteed--provided, of course, that the merchant followed the rules associated with the authorization process.)" [SET2]

automated information system 🤖 (I) This is an organized assembly of resources and procedures, meaning computing and communications equipment and services, plus their supporting facilities and personnel, that collect, record, process, store, transport, retrieve, or display information to accomplish a specified set of functions. Big system energy 🌈

availability ⭐ (I) This is the property of a system or system resource being accessible and usable on demand by an authorized system entity, according to the system's performance specs. Basically, a system is available if it delivers services according to its design whenever users ask for them. (See: critical, denial of service, reliability, survivability.)

(O) "The property of being accessible and usable upon demand by an authorized entity." [I7498 Part 2]

availability service 🛡️ (I) This is a security service that protects a system so it stays available.

(C) This service handles the security worries raised by denial-of-service attacks. It depends on proper management and control of system resources, so it leans on access control service and other security services too 🧚

back door 🚪 (I) This is a hardware or software mechanism that (a) gives access to a system and its resources by some other route than the usual procedure, (b) was deliberately left in place by the system's designers or maintainers, and (c) usually isn't publicly known. (See: trap door.)

(C) For example, a way into a computer that isn't the normal login. These paths don't always have bad intentions. Like, operating systems sometimes ship from the manufacturer with privileged accounts meant for field service technicians or the vendor's maintenance programmers. (See: trap door.)

back up vs. backup 💾 (I) Verb "back up": to store data for the purpose of making a backup copy. (See: archive.)

(I) Noun/adjective "backup": (1.) a reserve copy of data stored separately from the original, for use if the original gets lost or damaged. (See: archive.) (2.) alternate means to keep system functions working despite a disaster to system resources. (See: contingency plan.)

baggage 🧳 (D) ISDs SHOULD NOT use this term to describe a data element, except when it's written as "SET(trademark) baggage" with the following meaning:

(O) SET usage: an "opaque encrypted tuple, which is included in a SET message but appended as external data to the PKCS encapsulated data. This avoids superencryption of the previously encrypted tuple, but guarantees linkage with the PKCS portion of the message." [SET2]

bandwidth 📶 (I) Commonly used to mean the capacity of a communication channel to pass data through in a given amount of time. Usually expressed in bits per second.

bank identification number (BIN) 💳 (N) The digits of a credit card number that identify the issuing bank. (See: primary account number.)

(O) SET usage: the first six digits of a primary account number.

Basic Encoding Rules (BER) 🔢 (I) A standard for representing ASN.1 data types as strings of octets. [X690] (See: Distinguished Encoding Rules.)

bastion host 🏰 (I) A strongly protected computer that sits in a network protected by a firewall (or is part of one), and is the only host (or one of only a few hosts) in that network that can be directly accessed from networks on the other side of the firewall. Main character of the firewall, honestly.

(C) Filtering routers in a firewall usually restrict traffic from the outside network so it can only reach one host, the bastion host, which is usually part of the firewall. Since only this one host can be directly attacked, only this one needs to be super strongly protected, which makes security easier to maintain and less expensive. But to let legit internal and external users reach application resources through the firewall, higher layer protocols and services need to be relayed and forwarded by the bastion host. Some services (e.g., DNS and SMTP) have forwarding built in, while others (e.g., TELNET and FTP) need a proxy server on the bastion host.

BCA 📎 See: brand certification authority.

BCI 📎 See: brand CRL identifier.

Bell-LaPadula Model 🧠 (N) A formal, mathematical, state-transition model of security policy for multilevel-secure computer systems. [Bell]

(C) The model splits computer system elements into a set of subjects and a set of objects. To figure out whether a subject is authorized for a particular access mode on an object, the subject's clearance gets compared to the object's classification. The model defines a "secure state," where the only permitted access modes of subjects to objects follow a specified security policy. It's proven that each state transition keeps security by moving from secure state to secure state, which proves the system is secure. Slay 😤

"Confinement property" (also called "*-property", pronounced "star property"): A subject has write access to an object only if the classification of the object dominates the clearance of the subject.
"Simple security property": A subject has read access to an object only if the clearance of the subject dominates the classification of the object.
"Tranquillity property": The classification of an object does not change while the object is being processed by the system.

BER 🔁 See: Basic Encoding Rules.

beyond A1 🌌 (O) (1.) Formally, a level of security assurance that's beyond the highest level of criteria specified by the TCSEC. (2.) Informally, a level of trust so high that it can't be provided or verified by currently available assurance methods, and especially not by currently available formal methods. Unreal, bestie 😭

BIN 🔗 See: bank identification number.

bind 🔗 (I) To inseparably associate by applying some mechanism, like when a CA uses a digital signature to bind a subject and a public key together in a public-key certificate.

biometric authentication 🫆 (I) A method of generating authentication information for a person by digitizing measurements of a physical characteristic, like a fingerprint, hand shape, retina pattern, speech pattern (voiceprint), or handwriting.

bit 🔟 (I) The smallest unit of information storage. It's a contraction of "binary digit," and it's one of two symbols, "0" (zero) and "1" (one), used to represent binary numbers.

BLACK ⬛ (I) Designation for information system equipment or facilities that handle (and for data that contains) only ciphertext (or, depending on context, only unclassified information), and for that data itself. This term comes from U.S. Government COMSEC terminology. (See: RED, RED/BLACK separation.)

block cipher 🧱 (I) An encryption algorithm that breaks plaintext into fixed-size segments and uses the same key to transform each plaintext segment into a fixed-size segment of ciphertext. (See: mode, stream cipher.)

(C) Examples include Blowfish, DEA, IDEA, RC2, and SKIPJACK. A block cipher can also be adapted to have a different external interface, like a stream cipher's, by using a mode of operation to "package" the basic algorithm 🎁

Blowfish 🐡 (N) A symmetric block cipher with a variable-length key (32 to 448 bits), designed in 1993 by Bruce Schneier as an unpatented, license-free, royalty-free replacement for DES or IDEA. [Schn]

brand 🏷️ (I) A distinctive mark or name that identifies a product or business entity. Literally the iconic logo era 💖

(O) SET usage: the name of a payment card 💳 Financial institutions and other companies founded payment card brands, protect and advertise them, set and enforce the rules for using and accepting their cards, and run the networks that connect the financial institutions. These brands combine the issuer and acquirer roles when dealing with cardholders and merchants. [SET1]

$ brand certification authority (BCA) (O) SET usage: a CA owned by a payment card brand, like MasterCard, Visa, or American Express 🫶 [SET2] (See: certification hierarchy, SET.)

$ brand CRL identifier (BCI) (O) SET usage: a digitally signed list, issued by a BCA, of the names of CAs whose CRLs need to be processed when verifying signatures in SET messages. [SET2]

$ break (I) Cryptographic usage: successfully doing cryptanalysis to decrypt data or perform some other cryptographic function, without knowing the key that function needs in the first place 🔓 (This term applies to encrypted data or, more generally, to a cryptographic algorithm or cryptographic system.)

$ bridge (I) a computer that acts as a gateway between two networks (usually two LANs) at OSI layer 2 🌉 (See: router.)

$ British Standard 7799 (N) Part 1 is a standard code of practice that gives guidance on how to secure an information system. Part 2 specifies the management framework, objectives, and control requirements for information security management systems [B7799]. The certification scheme works like ISO 9000 ✨ It's in use in the UK, the Netherlands, Australia, and New Zealand, and it might get proposed as an ISO standard or adapted to be part of the Common Criteria.

$ browser (I) a client computer program that can retrieve and display information from servers on the World Wide Web 🌐

$ brute force (I) a cryptanalysis technique, or other kind of attack method, that uses an exhaustive procedure to try every possibility, one by one 😭

(C) For example, if the analyst already knows the decryption algorithm and has some ciphertext, a brute force way to find the original plaintext is to decrypt the message with every possible key. 🔑

$ BS7799 See: British Standard 7799.

$ byte (I) a fundamental unit of computer storage, and the smallest addressable unit in a computer's architecture. It usually holds one character of information and, today, usually means eight bits. (See: octet.) 🧚

(C) Bigger than a "bit" but smaller than a "word". Although "byte" almost always means "octet" today, bytes had other sizes (e.g., six bits, nine bits) in earlier computer architectures. 🍓

$ CA See: certification authority.

$ CA certificate (I) "A [digital] certificate for one CA issued by another CA." [X509]

(C) So basically, a digital certificate whose holder is able to issue digital certificates. A v3 X.509 public-key certificate may have a "basicConstraints" extension containing a cA value that "indicates whether or not the public key may be used to verify certificate signatures." 🧾

$ call back (I) an authentication technique for terminals that access a computer remotely over telephone lines. The host system disconnects the caller and then calls back on a telephone number that was previously authorized for that terminal 📞

$ capability (I) a token, usually an unforgeable data value (sometimes called a "ticket"), that gives the bearer or holder the right to access a system resource. Possessing the token is accepted by a system as proof that the holder has been authorized to access the resource named or indicated by the token. (See: access control list, credential, digital certificate.) 🎟️

$ CAPI See: cryptographic application programming interface.

$ CAPSTONE chip (N) an integrated circuit (the Mykotronx, Inc. MYK-82) with a Type II cryptographic processor that implements SKIPJACK, KEA, DSA, SHA, and basic mathematical functions to support asymmetric cryptography. It includes the key escrow feature of the CLIPPER chip. (See: FORTEZZA card.) 💎

$ card See: cryptographic card, FORTEZZA card, payment card, PC card, smart card, token.

$ card backup See: token backup.

$ card copy See: token copy.

$ card restore See: token restore.

$ cardholder (I) an entity that has been issued a card 💳

(O) SET usage: "The holder of a valid payment card account and user of software supporting electronic commerce." [SET2] A cardholder is issued a payment card by an issuer. SET makes sure that, in the cardholder's interactions with merchants, the payment card account information stays confidential 🔒 [SET1]

$ cardholder certificate (O) SET usage: a digital certificate issued to a cardholder once the cardholder's issuing financial institution approves it. It gets sent to merchants along with purchase requests and encrypted payment instructions, and it carries assurance that the account number has been validated by the issuing financial institution and can't be altered by a third party 🎀 [SET1]

$ cardholder certification authority (CCA) (O) SET usage: a CA responsible for issuing digital certificates to cardholders, and operated on behalf of a payment card brand, an issuer, or another party according to brand rules. A CCA maintains relationships with card issuers so that cardholder accounts can be verified. A CCA does not issue a CRL, but it does distribute CRLs issued by root CAs, brand CAs, geopolitical CAs, and payment gateway CAs. [SET2]

$ CAST (N) a design procedure for symmetric encryption algorithms, and a resulting family of algorithms, invented by C.A. (Carlisle Adams) and S.T. (Stafford Tavares) 🦋 [R2144, R2612]

$ category (I) a grouping of sensitive information items to which a non-hierarchical restrictive security label is applied to give the data extra protection. (See: compartment.) 🏷️

$ CAW See: certification authority workstation.

$ CBC See: cipher block chaining.

$ CCA See: cardholder certification authority.

$ CCITT (N) Acronym for the French translation of International Telephone and Telegraph Consultative Committee. It's now renamed ITU-T 🇫🇷

$ CERT See: computer emergency response team.

$ certificate (I) General English usage: a document that attests to the truth of something or to the ownership of something 📜

$ certificate authority (D) ISDs SHOULD NOT use this term, because it looks like sloppy use of "certification authority", which is the term standardized by X.509 🙈

$ certificate chain (D) ISDs SHOULD NOT use this term, because it duplicates the meaning of a standardized term. Instead, use "certification path" 🛤️

$ certificate chain validation (D) ISDs SHOULD NOT use this term, because it duplicates the meaning of standardized terms and mixes concepts in a potentially misleading way. Instead, use "certificate validation" or "path validation", depending on what is meant. (See: validate vs. verify.) 🫠

$ certificate creation (I) the act or process by which a CA sets the values of a digital certificate's data fields and signs it. (See: issue.) ✍️

$ certificate expiration (I) the event that happens when a certificate stops being valid because its assigned lifetime has been exceeded ⏳ (See: certificate revocation, validity period.)

$ certificate extension See: extension.

$ certificate holder (D) ISDs SHOULD NOT use this term as a synonym for the subject of a digital certificate, because the term is potentially ambiguous. For example, the term could also refer to a system entity, such as a repository, that simply has possession of a copy of the certificate. (See: certificate owner.) 👀

$ certificate management (I) the functions that a CA may perform during the life cycle of a digital certificate, including the following:

Acquire and verify data items to bind into the certificate.
Encode and sign the certificate.
Store the certificate in a directory or repository.
Renew, rekey, and update the certificate.
Revoke the certificate and issue a CRL.

(See: archive management, certificate management, key management, security architecture, token management.) 🗂️

$ certificate owner (D) ISDs SHOULD NOT use this term as a synonym for the subject of a digital certificate, because the term is potentially ambiguous. For example, the term could also refer to a system entity, such as a corporation, that has acquired a certificate to operate some other entity, such as a Web server. (See: certificate holder.) 🏢

$ certificate policy (I) "A named set of rules that indicates the applicability of a certificate to a particular community and/or class of application with common security requirements." [X509] (See: certification practice statement.) 📋

(C) A certificate policy can help a certificate user decide whether a certificate should be trusted in a particular application. "For example, a particular certificate policy might indicate applicability of a type of certificate for the authentication of electronic data interchange transactions for the trading goods within a given price range." [R2527] 🛍️

(C) A v3 X.509 public-key certificate may have a "certificatePolicies" extension that lists certificate policies, recognized by the issuing CA, that apply to the certificate and govern its use. Each policy is denoted by an object identifier and may optionally have certificate policy qualifiers. 🔖

(C) SET usage: Every SET certificate specifies at least one certificate policy, that of the SET root CA. SET uses certificate policy qualifiers to point to the actual policy statement and to add qualifying policies to the root policy. (See: SET qualifier.) 👑

$ certificate policy qualifier (I) information that pertains to a certificate policy and is included in a "certificatePolicies" extension in a v3 X.509 public-key certificate 🧩

$ certificate reactivation (I) the act or process by which a digital certificate, which a CA has designated for revocation but not yet listed on a CRL, is returned to the valid state 🔄

$ certificate rekey (I) the act or process by which an existing public-key certificate has its public key value changed, by issuing a new certificate with a different (usually new) public key. (See: certificate renewal, certificate update, rekey.) 🔑

(C) For an X.509 public-key certificate, the essence of rekey is that the subject stays the same and a new public key is bound to that subject. Other changes are made, and the old certificate is revoked, only as required by the PKI and CPS in support of the rekey. If the changes go beyond that, the process is a "certificate update". 💖

(O) MISSI usage: okay, so rekeying a MISSI X.509 public-key certificate means the issuing authority makes a brand new certificate that's identical to the old one, except the new one has a new, different KEA key, or a new, different DSS key, or new, different KEA and DSS keys 🔑✨ The new certificate also gets a different serial number and may have a different validity period. Every newly generated key gets its own new key creation date and maximum key lifetime period 📅 And if a new KEA key is generated, that key is assigned a new KMID 🎀 The old certificate stays valid until it expires, but it may not be further renewed, rekeyed, or updated 🥀

$ certificate renewal

(I) The act or process by which the validity of the data binding asserted by an existing public-key certificate is extended in time by issuing a new certificate. (See: certificate rekey, certificate update.) 🦋

(C) For an X.509 public-key certificate, this term means the validity period is extended (and, of course, a new serial number is assigned), but the binding of the public key to the subject and to other data items stays the same. The other data items are changed, and the old certificate is revoked, only as required by the PKI and CPS to support the renewal. If the changes go beyond that, the process is a "certificate rekey" or "certificate update" 💅

$ certificate request

(D) ISDs SHOULD NOT use this term because it looks like imprecise use of a term standardized by PKCS #10 and used in PKIX. Instead, use the standard term, "certification request" 🙈

$ certificate revocation

(I) The event that occurs when a CA declares that a previously valid digital certificate issued by that CA has become invalid, usually stated with a revocation date 💀

(C) In X.509, a revocation is announced to potential certificate users by issuing a CRL that mentions the certificate. Revocation and listing on a CRL is only necessary before certificate expiration ⏳

$ certificate revocation list (CRL)

(I) A data structure that enumerates digital certificates that have been invalidated by their issuer prior to when they were scheduled to expire. (See: certificate expiration, X.509 certificate revocation list.) 📜

(O) "A signed list indicating a set of certificates that are no longer considered valid by the certificate issuer. After a certificate appears on a CRL, it is deleted from a subsequent CRL after the certificate's expiry. CRLs may be used to identify revoked public-key certificates or attribute certificates and may represent revocation of certificates issued to authorities or to users. The term CRL is also commonly used as a generic term applying to all the different types of revocation lists, including CRLs, ARLs, ACRLs, etc." [FPDAM]

$ certificate revocation tree

(I) A mechanism for distributing notice of certificate revocations. It uses a tree of hash results that is signed by the tree's issuer. It offers an alternative to issuing a CRL, but is not supported in X.509. (See: certificate status responder.) 🌳

$ certificate serial number

(I) An integer value that (a) is associated with, and may be carried in, a digital certificate; (b) is assigned to the certificate by the certificate's issuer; and (c) is unique among all the certificates produced by that issuer. 🔢

(O) "An integer value, unique within the issuing CA, which is unambiguously associated with a certificate issued by that CA." [X509]

$ certificate status responder

(N) FPKI usage: A trusted on-line server that acts for a CA to provide authenticated certificate status information to certificate users. [FPKI] It offers an alternative to issuing a CRL, but is not supported in X.509. (See: certificate revocation tree.) 🛰️

$ certificate update

(I) The act or process by which non-key data items bound in an existing public-key certificate, especially authorizations granted to the subject, are changed by issuing a new certificate. (See: certificate rekey, certificate renewal.) 🎨

(C) For an X.509 public-key certificate, the essence of this process is that fundamental changes are made in the data that is bound to the public key, such that it is necessary to revoke the old certificate. (Otherwise, the process is only a "certificate rekey" or "certificate renewal".)

$ certificate user

(I) A system entity that depends on the validity of information (such as another entity's public key value) provided by a digital certificate. (See: relying party.) 🫶

(O) "An entity that needs to know, with certainty, the public key of another entity." [X509]

(C) The system entity may be a human being or an organization, or a device or process under the control of a human or an organization. 🧚

(D) ISDs SHOULD NOT use this term as a synonym for the "subject" of a certificate. 🙅‍♀️

$ certificate validation

(I) An act or process by which a certificate user establishes that the assertions made by a digital certificate can be trusted. (See: valid certificate, validate vs. verify.) ✅

(O) "The process of ensuring that a certificate is valid including possibly the construction and processing of a certification path, and ensuring that all certificates in that path have not expired or been revoked." [FPDAM]

(C) To validate a certificate, a certificate user checks that the certificate is properly formed and signed and currently in force:

Checks the signature: Employs the issuer's public key to verify the digital signature of the CA who issued the certificate in question. If the verifier obtains the issuer's public key from the issuer's own public-key certificate, that certificate should be validated, too. That validation may lead to yet another certificate to be validated, and so on. Thus, in general, certificate validation involves discovering and validating a certification path. 🔍
Checks the syntax and semantics: Parses the certificate's syntax and interprets its semantics, applying rules specified for and by its data fields, such as for critical extensions in an X.509 certificate. 🧩
Checks currency and revocation: Verifies that the certificate is currently in force by checking that the current date and time are within the validity period (if that is specified in the certificate) and that the certificate is not listed on a CRL or otherwise announced as invalid. (CRLs themselves require a similar validation process.) 🕰️

$ certification

(I) Information system usage: Technical evaluation (usually made in support of an accreditation action) of an information system's security features and other safeguards to establish the extent to which the system's design and implementation meet specified security requirements. [FP102] (See: accreditation.) 🛡️

(I) Digital certificate usage: The act or process of vouching for the truth and accuracy of the binding between data items in a certificate. (See: certify.) 🤝

(I) Public key usage: The act or process of vouching for the ownership of a public key by issuing a public-key certificate that binds the key to the name of the entity that possesses the matching private key. In addition to binding a key to a name, a public-key certificate may bind those items to other restrictive or explanatory data items. (See: X.509 public-key certificate.) 🗝️

(O) SET usage: "The process of ascertaining that a set of requirements or criteria has been fulfilled and attesting to that fact to others, usually with some written instrument. A system that has been inspected and evaluated as fully compliant with the SET protocol by duly authorized parties and process would be said to have been certified compliant." [SET2]

$ certification authority (CA)

(I) An entity that issues digital certificates (especially X.509 certificates) and vouches for the binding between the data items in a certificate. 👑

(O) "An authority trusted by one or more users to create and assign certificates. Optionally, the certification authority may create the user's keys." [X509]

(C) Certificate users depend on the validity of information provided by a certificate. Thus, a CA should be someone that certificate users trust, and usually holds an official position created and granted power by a government, a corporation, or some other organization. A CA is responsible for managing the life cycle of certificates (see: certificate management) and, depending on the type of certificate and the CPS that applies, may be responsible for the life cycle of key pairs associated with the certificates (see: key management). 🏛️

$ certification authority workstation (CAW)

(I) A computer system that enables a CA to issue digital certificates and supports other certificate management functions as required. 💻

$ certification hierarchy

(I) A tree-structured (loop-free) topology of relationships among CAs and the entities to whom the CAs issue public-key certificates. (See: hierarchical PKI.) 🌲

(C) In this structure, one CA is the top CA, the highest level of the hierarchy. (See: root, top CA.) The top CA may issue public-key certificates to one or more additional CAs that form the second highest level. Each of these CAs may issue certificates to more CAs at the third highest level, and so on. The CAs at the second-lowest of the hierarchy issue certificates only to non-CA entities, called "end entities" that form the lowest level. (See: end entity.) Thus, all certification paths begin at the top CA and descend through zero or more levels of other CAs. All certificate users base path validations on the top CA's public key. 🌟

(O) MISSI usage: A MISSI certification hierarchy has three or four levels of CAs:

A CA at the highest level, the top CA, is a "policy approving authority".
A CA at the second-highest level is a "policy creation authority".
A CA at the third-highest level is a local authority called a "certification authority".
A CA at the fourth-highest (optional) level is a "subordinate certification authority".

(O) PEM usage: A PEM certification hierarchy has three levels of CAs [R1422]:

The highest level is the "Internet Policy Registration Authority".
A CA at the second-highest level is a "policy certification authority".
A CA at the third-highest level is a "certification authority".

(O) SET usage: A SET certification hierarchy has three or four levels of CAs:

The highest level is a "SET root CA".
A CA at the second-highest level is a "brand certification authority".
A CA at the third-highest (optional) level is a "geopolitical certification authority".
A CA at the fourth-highest level is a "cardholder CA", a "merchant CA", or a "payment gateway CA".

certification path 🛤️

Okay so, a certification path is an ordered chain of public-key certificates (or public-key certificates followed by one attribute certificate) that lets a certificate user check the signature on the last certificate in the chain. Once that check passes, the user can get a certified public key, or certified attributes, for the entity that is the subject of that last certificate. (See: certificate validation, valid certificate.) 💖

(O) "An ordered sequence of certificates of objects in the [X.500 Directory Information Tree] which, together with the public key of the initial object in the path, can be processed to obtain that of the final object in the path." [X509, R2527]

(C) The path is the "list of certificates needed to allow a particular user to obtain the public key of another." [X509] The list is "linked," meaning the digital signature on each certificate (except the first one) is verified by the public key in the certificate right before it. The private key used to sign a certificate and the public key in the preceding certificate form a key pair owned by whoever did the signing. 🔗

(C) Now, about that word "particular" in the X.509 quote 👀. It's doing real work! A path that one certificate user can validate might not be validatable by a different user. That's because the first certificate should be a trusted certificate (it might be a root certificate), or the signature on the first certificate should be checked against a trusted key (it might be a root key). Trust is defined relative to each user, not absolutely for everyone, so it's giving "your trust, your rules" 💅.

certification policy 🙅‍♀️

(D) ISDs SHOULD NOT use this term. Instead, use either "certificate policy" or "certification practice statement," depending on what you actually mean. 🙈

certification practice statement (CPS) 📜

(I) "A statement of the practices which a certification authority employs in issuing certificates." [ABA96, R2527] (See: certificate policy.) ✨

(C) A CPS is a published security policy that helps a certificate user decide whether a certificate from a particular CA is trustworthy enough for a particular application. A CPS can be (a) a declaration by a CA of the details of the system and practices it uses in its certificate management operations, (b) part of a contract between the CA and an entity that gets a certificate, (c) a statute or regulation that applies to the CA, or (d) a combo of these, spread across multiple documents. [ABA] 📚

(C) A CPS is usually more detailed and procedural than a certificate policy. A CPS applies to one particular CA or CA community, while a certificate policy applies across CAs or communities. A single CA with one CPS can support multiple certificate policies, which might serve different application purposes or different user communities. Multiple CAs, each with a different CPS, can support the same certificate policy. [R2527] 🌈

certification request 📝

(I) An algorithm-independent transaction format, defined by PCKS #10 and used in PKIX, that contains a DN, a public key, and optionally a set of attributes. The entity asking for certification signs it all together and sends it to a CA, which transforms the request into an X.509 public-key certificate or another type of certificate. 🦋

certify 🎀

(I) Issue a digital certificate and thus vouch for the truth, accuracy, and binding between data items in the certificate (e.g., see: X.509 public key certificate), such as the identity of the certificate's subject and the ownership of a public key. (See: certification.) 💌

(C) To "certify a public key" means to issue a public-key certificate that vouches for the binding between the certificate's subject and the key. 🔑

(I) The act by which a CA employs measures to verify the truth, accuracy, and binding between data items in a digital certificate. ✅

CFB 🔁

See: cipher feedback.

Challenge Handshake Authentication Protocol (CHAP) 🤝

(I) A peer entity authentication method for PPP. It uses a randomly-generated challenge and requires a matching response that depends on a cryptographic hash of the challenge and a secret key. [R1994] (See: challenge-response, PAP.) 🧩

challenge-response 🎯

(I) An authentication process that verifies an identity by requiring correct authentication information to be provided in response to a challenge. In a computer system, the authentication information is usually a value that has to be computed in response to an unpredictable challenge value. 🔐

Challenge-Response Authentication Mechanism (CRAM) 💬

(I) IMAP4 usage: A mechanism [R2195], intended for use with IMAP4 AUTHENTICATE, by which an IMAP4 client uses a keyed hash [R2104] to authenticate itself to an IMAP4 server. (See: POP3 APOP.) 📨

(C) The server includes a unique timestamp in its ready response to the client. The client replies with the client's name and the hash result of applying MD5 to a string made by concatenating the timestamp with a shared secret that only the client and the server know. Secret-keeping, but make it a whole mechanism 🤫.

channel 🌊

(I) An information transfer path within a system. (See: covert channel.) 🛣️

CHAP 🔗

See: Challenge Handshake Authentication Protocol.

checksum ✔️

(I) A value that (a) is computed by a function that depends on the contents of a data object, and (b) is stored or transmitted together with the object, for the purpose of detecting changes in the data. (See: cyclic redundancy check, data integrity service, error detection code, hash, keyed hash, protected checksum.) 🧮

(C) To gain confidence that a data object hasn't been changed, an entity that later uses the data can compute a checksum and compare it with the checksum that was stored or transmitted with the object. 👯

(C) Computer systems and networks use checksums (and other mechanisms) to detect accidental changes in data. However, active wiretapping that changes data could also change an accompanying checksum to match the altered data. So some checksum functions by themselves are not good countermeasures for active attacks. To protect against active attacks, the checksum function needs to be well-chosen (see: cryptographic hash), and the checksum result needs to be cryptographically protected (see: digital signature, keyed hash). 🚨

chosen-ciphertext attack 🕵️‍♀️

(I) A cryptanalysis technique in which the analyst tries to determine the key from knowledge of plaintext that corresponds to ciphertext selected (i.e., dictated) by the analyst. 😤

chosen-plaintext attack 🕵️

(I) A cryptanalysis technique in which the analyst tries to determine the key from knowledge of ciphertext that corresponds to plaintext selected (i.e., dictated) by the analyst. 🫣

CIAC 🏛️

See: Computer Incident Advisory Capability.

CIK 🗝️

See: cryptographic ignition key.

cipher 🔒

(I) A cryptographic algorithm for encryption and decryption. 🪄

cipher block chaining (CBC) ⛓️

(I) A block cipher mode that enhances electronic codebook mode by chaining together the blocks of ciphertext it produces. [FP081] (See: [R1829], [R2451].) 🧶

(C) This mode works by combining (exclusive OR-ing) the algorithm's ciphertext output block with the next plaintext block, forming the next input block for the algorithm. 🔄

cipher feedback (CFB) 🔁

(I) A block cipher mode that enhances electronic code book mode by chaining together the blocks of ciphertext it produces, and operates on plaintext segments of variable length less than or equal to the block length. [FP081] 🌸

(C) This mode works by using the previously generated ciphertext segment as the algorithm's input (i.e., by "feeding back" the ciphertext) to generate an output block. Then it combines (exclusive OR-ing) that output block with the next plaintext segment (block length or less) to form the next ciphertext segment. 💫

ciphertext 🫥

(I) Data that has been transformed by encryption so that its semantic information content (i.e., its meaning) is no longer intelligible or directly available. (See: cleartext, plaintext.) 🙈

(O) "Data produced through the use of encipherment. The semantic content of the resulting data is not available." [I7498 Part 2]

ciphertext-only attack 👀

(I) A cryptanalysis technique in which the analyst tries to determine the key solely from knowledge of intercepted ciphertext. The analyst may also know other clues, such as the cryptographic algorithm, the language the plaintext was written in, the subject matter of the plaintext, and some probable plaintext words. 🕶️

CIPSO 🏷️

See: Common IP Security Option.

CKL 🚫

See: compromised key list.

class 2, 3, 4, or 5 🥇

(O) U.S. Department of Defense usage: Levels of PKI assurance based on the risk and value of the information to be protected [DOD3]:

Class 2: For handling low-value information (unclassified, not mission-critical, or low monetary value), or protection of system-high information in a low- to medium-risk environment. 🌱
Class 3: For handling medium-value information in a low- to medium-risk environment. Typically requires identification of a system entity as a legal person, rather than merely a member of an organization. 🌿
Class 4: For handling medium- to high-value information in any environment. Typically requires identification of an entity as a legal person, rather than merely a member of an organization, and a cryptographic hardware token for protection of keying material. 🌳
Class 5: For handling high-value information in a high-risk environment. 👑

classification / classification level 🏷️

(I) (1.) A grouping of classified information to which a hierarchical, restrictive security label is applied to increase protection of the data. (2.) The level of protection that is required to be applied to that information. (See: security level.) 💅

classified 🤫

(I) Refers to information (stored or conveyed, in any form) that a security policy formally requires to get data confidentiality service and to be marked with a security label (which in some cases might be implicit) to show its protected status. (See: unclassified.) 🔐

(C) The term is mainly used in government, especially in the military, although the concept behind it also applies outside government. In the U.S. Department of Defense, for example, it means information that has been determined, under Executive Order 12958 ("Classified National Security Information," 20 April 1995) or any predecessor order, to require protection against unauthorized disclosure, and that is marked to show its classified status when it's in documentary form. 📄

clean system 🧼

(I) A computer system in which the operating system and application system software and files have just been freshly installed from trusted software distribution media. ✨

clearance

See: security clearance.

clearance level ✨

(I) The security level of information to which a security clearance authorizes a person to have access. 🔐

cleartext 🔓

(I) Data in which the semantic information content (i.e., the meaning) is intelligible or is directly available. (See: plaintext.)

(O) "Intelligible data, the semantic content of which is available." [I7498 Part 2]

(D) ISDs SHOULD NOT use this term as a synonym for "plaintext", the input to an encryption operation, because the plaintext input to encryption may itself be ciphertext that was output from another operation. (See: superencryption.) 🙈 Not the same thing, babe!

client 🧚

(I) A system entity that requests and uses a service provided by another system entity, called a "server". (See: server.)

(C) Usually, the requesting entity is a computer process, and it makes the request on behalf of a human user. In some cases, the server may itself be a client of some other server. 🔁

CLIPPER chip 🔑

(N) The Mykotronx, Inc. MYK-82, an integrated microcircuit with a cryptographic processor that implements the SKIPJACK encryption algorithm and supports key escrow. (See: CAPSTONE, Escrowed Encryption Standard.)

(C) The key escrow scheme for a chip involves a SKIPJACK key common to all chips that protects the unique serial number of the chip, and a second SKIPJACK key unique to the chip that protects all data encrypted by the chip. The second key is escrowed as split key components held by NIST and the U.S. Treasury Department. 🗝️

closed security environment 🏰

(O) U.S. Department of Defense usage: A system environment that meets both of the following conditions: (a) Application developers (including maintainers) have sufficient clearances and authorizations to provide an acceptable presumption that they have not introduced malicious logic. (b) Configuration control provides sufficient assurance that system applications and the equipment they run on are protected against the introduction of malicious logic prior to and during the operation of applications. [NCS04] (See: open security environment.)

code 🌸

(I) noun: A system of symbols used to represent information, which might originally have some other representation. (See: encode.)

(D) ISDs SHOULD NOT use this term as synonym for the following: (a) "cipher", "hash", or other words that mean "a cryptographic algorithm"; (b) "ciphertext"; or (c) "encrypt", "hash", or other words that refer to applying a cryptographic algorithm.

(D) ISDs SHOULD NOT use this word as an abbreviation for the following terms: country code, cyclic redundancy code, Data Authentication Code, error detection code, Message Authentication Code, object code, or source code. To avoid misunderstanding, use the fully qualified term, at least at the point of first usage. 📝 Spell it out, no shortcuts!

color change 🎨

(I) In a system that is being operated in periods processing mode, the act of purging all information from one processing period and then changing over to the next processing period.

Common Criteria / Common Criteria for Information Technology Security 🏅

(N) "The Common Criteria" is a standard for evaluating information technology products and systems, such as operating systems, computer networks, distributed systems, and applications. It states requirements for security functions and for assurance measures. [CCIB]

(C) Canada, France, Germany, the Netherlands, the United Kingdom, and the United States (NIST and NSA) began developing this standard in 1993, based on the European ITSEC, the Canadian Trusted Computer Product Evaluation Criteria (CTCPEC), and the U.S. "Federal Criteria for Information Technology Security" (FC) and its precursor, the TCSEC. Work was done in cooperation with ISO/IEC Joint Technical Committee 1 (Information Technology), Subcommittee 27 (Security Techniques), Working Group 3 (Security Criteria). Version 2.1 of the Criteria is equivalent to ISO's International Standard 15408 [I15408]. The U.S. Government intends that this standard eventually will supersede both the TCSEC and FIPS PUB 140-1. (See: NIAP.) 🌍 The whole international glow-up!

(C) The standard addresses data confidentiality, data integrity, and availability and may apply to other aspects of security. It focuses on threats to information arising from human activities, malicious or otherwise, but may apply to non-human threats. It applies to security measures implemented in hardware, firmware, or software. It does not apply to (a) administrative security not related directly to technical security, (b) technical physical aspects of security such as electromagnetic emanation control, (c) evaluation methodology or administrative and legal framework under which the criteria may be applied, (d) procedures for use of evaluation results, or (e) assessment of inherent qualities of cryptographic algorithms. 🚫 Not everything is in scope, okay!

Common IP Security Option (CIPSO)

See: (secondary definition under) Internet Protocol Security Option.

common name 🪪

(I) A character string that (a) may be a part of the X.500 DN of a Directory object ("commonName" attribute), (b) is a (possibly ambiguous) name by which the object is commonly known in some limited scope (such as an organization), and (c) conforms to the naming conventions of the country or culture with which it is associated. [X520] (See: ("subject" and "issuer" under) X.509 public-key certificate.)

communication security (COMSEC) 📡

(I) Measures that implement and assure security services in a communication system, particularly those that provide data confidentiality and data integrity and that authenticate communicating entities.

(C) Usually understood to include cryptographic algorithms and key management methods and processes, devices that implement them, and the life cycle management of keying material and devices. 🔧

community string 🫶

(I) A community name in the form of an octet string that serves as a cleartext password in SNMP version 1. [R1157] 😬 Yikes, that's not a password, that's a postcard!

compartment 🗂️

(I) A grouping of sensitive information items that require special access controls beyond those normally provided for the basic classification level of the information. (See: category.)

compromise

See: data compromise, security compromise.

compromised key list (CKL) 🚨

(O) MISSI usage: A list that identifies keys for which unauthorized disclosure or alteration may have occurred. (See: compromise.)

(C) A CKL is issued by an CA, like a CRL is issued. But a CKL lists only KMIDs, not subjects that hold the keys, and not certificates in which the keys are bound. 👀

COMPUSEC

See: computer security.

computer emergency response team (CERT) 🚑

(I) An organization that studies computer and network INFOSEC in order to provide incident response services to victims of attacks, publish alerts concerning vulnerabilities and threats, and offer other information to help improve computer and network security. (See: CSIRT, security incident.)

(C) For example, the CERT Coordination Center at Carnegie-Mellon University (sometimes called "the" CERT) and the Computer Incident Advisory Capability.

Computer Incident Advisory Capability (CIAC)

(N) A computer emergency response team in the U.S. Department of Energy. ⚡

computer network 🕸️

(I) A collection of host computers together with the subnetwork or internetwork through which they can exchange data.

(C) This definition is intended to cover systems of all sizes and types, ranging from the complex Internet to a simple system composed of a personal computer dialing in as a remote terminal of another computer. 💻

computer security (COMPUSEC) 🖥️

(I) Measures that implement and assure security services in a computer system, particularly those that assure access control service.

(C) Usually understood to include functions, features, and technical characteristics of computer hardware and software, especially operating systems.

computer security incident response team (CSIRT) 🦸

(I) An organization "that coordinates and supports the response to security incidents that involve sites within a defined constituency." [R2350] (See: CERT, FIRST, security incident.)

Provide a (secure) channel for receiving reports about suspected security incidents. 📬
Provide assistance to members of its constituency in handling the incidents. 🤝
Disseminate incident-related information to its constituency and other involved parties. 📢

computer security object 🧩

(I) The definition or representation of a resource, tool, or mechanism used to maintain a condition of security in computerized environments. Includes many elements referred to in standards that are either selected or defined by separate user communities. [CSOR] (See: object identifier, Computer Security Objects Register.)

Computer Security Objects Register (CSOR) 📚

(N) A service operated by NIST is establishing a catalog for computer security objects to provide stable object definitions identified by unique names. The use of this register will enable the unambiguous specification of security parameters and algorithms to be used in secure data exchanges.

(C) The CSOR follows registration guidelines established by the international standards community and ANSI. Those guidelines establish minimum responsibilities for registration authorities and assign the top branches of an international registration hierarchy. Under that international registration hierarchy the CSOR is responsible for the allocation of unique identifiers under the branch {joint-iso-ccitt(2) country(16) us(840) gov(101) csor(3)}. 🌳

COMSEC

See: communication security.

confidentiality

See: data confidentiality. 🤫

configuration control ⚙️

(I) The process of regulating changes to hardware, firmware, software, and documentation throughout the development and operational life of a system. (See: administrative security.)

(C) Configuration control helps protect against unauthorized or malicious alteration of a system and thus provides assurance of system integrity. (See: malicious logic.) 🛡️

confinement property

See: (secondary definition under) Bell-LaPadula Model.

connectionless data integrity service 🦋

(I) A security service that provides data integrity service for an individual IP datagram, by detecting modification of the datagram, without regard to the ordering of the datagram in a stream of datagrams.

(C) A connection-oriented data integrity service would be able to detect lost or reordered datagrams within a stream of datagrams. 🌊 That's the difference, and it's a whole vibe!

contingency plan 🌸 (I) okay so a contingency plan is basically your emergency backup plan 🆘. It covers emergency response, backup operations, and post-disaster recovery in a system, as part of a security program, so critical system resources stay available and operations can keep going in a crisis. [NCS04] (See: availability.)

controlled security mode 🔒 (D) ISDs SHOULD NOT use this term 🙅‍♀️. It came from an earlier version of the U.S. Department of Defense policy that regulates system accreditation, and the current version folded it into "partitioned security mode." [DOD2]

(C) this one refers to a mode of operation of an information system where at least some users with access to the system have neither a security clearance nor a need-to-know for all the classified material in it. The big difference is that separating users and classified material, by clearance and classification level, is not essentially under operating system control the way it is in "multilevel security mode" 👀.

(C) controlled mode was meant to be a clever middle ground 🦋. It let teams meet Defense security requirements in ways that were less restrictive than "dedicated security mode" and "system high security mode," while keeping the risk lower than what usually comes with the real "multilevel security mode." The plan was to add explicit augmenting measures that reduce or remove a big chunk of system software vulnerability, plus specific limits on the security clearance levels of users who can access the system at the same time.

cookie 🍪 (I) access control usage: a synonym for "capability" or "ticket" in an access control system.

(I) IPsec usage: data exchanged by ISAKMP to prevent certain denial-of-service attacks while a security association is being set up.

(I) HTTP usage: data exchanged between an HTTP server and a browser (a client of the server) so state information can be stored on the client side and retrieved later for server use.

(C) okay the HTTP one is so iconic 💖. A server can send a cookie along with data to a client, and the client keeps it even after the HTTP connection closes. That's how a server keeps persistent client-side state for HTTP-based applications and pulls that state back in later connections. A cookie can include a description of the range of URLs where the state is valid, and any future requests the client makes in that range will also send the current cookie value back to the server. real talk 🥺: cookies can be used to build profiles of web usage habits, so they may infringe on personal privacy.

Coordinated Universal Time (UTC) ⏰ (N) UTC is derived from International Atomic Time (TAI) by adding a number of leap seconds. The International Bureau of Weights and Measures computes TAI once each month by averaging data from many laboratories. (See: GeneralizedTime, UTCTime.)

copy 📄 See: card copy.

correctness integrity ✅ (I) accuracy and consistency of the information that data values represent, rather than of the data itself. It's closely related to accountability and error handling. (See: data integrity, source integrity.)

correctness proof 🧮 (I) a mathematical proof of consistency between a specification for system security and the implementation of that specification. (See: formal specification.)

countermeasure 🛡️ (I) an action, device, procedure, or technique that reduces a threat, a vulnerability, or an attack. It can do that by eliminating or preventing it, by minimizing the harm it can cause, or by discovering and reporting it so corrective action can be taken.

(C) in an Internet protocol, a countermeasure may take the form of a protocol feature, an element function, or a usage constraint ✨.

country code 🌍 (I) an identifier that is defined for a nation by ISO. [I3166]

(C) for each nation, ISO Standard 3166 defines a unique two-character alphabetic code, a unique three-character alphabetic code, and a three-digit code. Among many uses of these codes, the two-character codes are used as top-level domain names 🌐.

covert channel 🕵️‍♀️ (I) A intra-system channel that permits two cooperating entities, without exceeding their access authorizations, to transfer information in a way that violates the system's security policy. (See: channel, out of band.)

(O) "A communications channel that allows two cooperating processes to transfer information in a manner that violates the system's security policy." [NCS04]

(C) the cooperating entities can be two insiders, or an insider and an outsider. An outsider has no access authorization at all, obviously 🙄. A covert channel is a system feature that the system architects neither designed nor intended for information transfer, and there are two flavours:

"Timing channel": a system feature that enables one system entity to signal information to another by modulating its own use of a system resource in a way that affects the system response time the second entity observes. 🕰️
"Storage channel": a system feature that enables one system entity to signal information to another entity by directly or indirectly writing a storage location that is later directly or indirectly read by the second entity. 💾

CPS 📝 See: certification practice statement.

cracker 🏴‍☠️ (I) someone who tries to break the security of, and gain access to, someone else's system without being invited to do so. (See: hacker and intruder.) not it 🙅‍♀️.

CRAM 🧩 See: Challenge-Response Authentication Mechanism.

CRC 🔢 See: cyclic redundancy check.

credential(s) 🪪 (I) data that is transferred or presented to establish either a claimed identity or the authorizations of a system entity. (See: authentication information, capability, ticket.)

(O) "Data that is transferred to establish the claimed identity of an entity." [I7498 Part 2]

critical 🚨

(I) "Critical" system resource: a condition of a service or other system resource where denying access to it (i.e., lacking its availability) would jeopardize a system user's ability to perform a primary function, or would result in other serious consequences. (See: availability, sensitive.)
(N) "Critical" extension: each extension of an X.509 certificate (or CRL) is marked as either critical or non-critical. If an extension is critical and a certificate user (or CRL user) doesn't recognize the extension type or doesn't implement its semantics, then the user is required to treat the certificate (or CRL) as invalid 😱. If an extension is non-critical, a user who doesn't recognize or implement that extension type is permitted to ignore the extension and process the rest of the certificate (or CRL) 🫶.

CRL 📜 See: certificate revocation list.

CRL distribution point 📬 See: distribution point.

CRL extension 🧩 See: extension.

cross-certificate 🔗 See: cross-certification.

cross-certification 🤝 (I) the act or process by which two CAs each certify a public key of the other, issuing a public-key certificate to that other CA.

(C) cross-certification lets users validate each other's certificates when the users are certified under different certification hierarchies 💅.

cryptanalysis 🔐 (I) the mathematical science that deals with analysis of a cryptographic system in order to gain the knowledge needed to break or circumvent the protection the system is designed to provide. (See: cryptology.)

(O) "The analysis of a cryptographic system and/or its inputs and outputs to derive confidential variables and/or sensitive data including cleartext." [I7498 Part 2]

(C) the "O" definition states the traditional goal of cryptanalysis, which is converting ciphertext to plaintext (usually cleartext) without knowing the key. But that definition only applies to encryption systems. Today the term is used for all kinds of cryptographic algorithms and key management, and the "I" definition reflects that 🧠. In every case, a cryptanalyst is trying to uncover or reproduce someone else's sensitive data, such as cleartext, a key, or an algorithm. The basic cryptanalytic attacks on encryption systems are ciphertext-only, known-plaintext, chosen-plaintext, and chosen-ciphertext, and these generalize to the other kinds of cryptography 🕵️.

crypto 🚫 (D) except as part of certain long-established terms listed in this Glossary, ISDs SHOULD NOT use this abbreviated term, because it may be misunderstood. Instead, use "cryptography" or "cryptographic" 💅.

cryptographic algorithm 🔣 (I) an algorithm that employs the science of cryptography, including encryption algorithms, cryptographic hash algorithms, digital signature algorithms, and key agreement algorithms.

cryptographic application programming interface (CAPI) 🧑‍💻 (I) the source code formats and procedures through which an application program accesses cryptographic services. They're defined abstractly, compared to their actual implementation. For example, see: PKCS #11, [R2628].

cryptographic card 💳 (I) a cryptographic token in the form of a smart card or a PC card.

cryptographic component 🧩 (I) a generic term for any system component that involves cryptography. (See: cryptographic module.)

cryptographic hash 🔁 See: (secondary definition under) hash function.

cryptographic ignition key (CIK) 🗝️ (I) a physical (usually electronic) token used to store, transport, and protect cryptographic keys. (Sometimes abbreviated as "crypto ignition key".)

(C) a typical use is to divide a split key between a CIK and a cryptographic module, so you need to combine the two to regenerate a key-encrypting key, which activates the module and the other keys it contains ⚡.

cryptographic key 🔑 (I) usually shortened to just "key." an input parameter that varies the transformation performed by a cryptographic algorithm.

(O) "A sequence of symbols that controls the operations of encipherment and decipherment." [I7498 Part 2]

(C) if a key value needs to be kept secret, the sequence of symbols (usually bits) that makes it up should be random, or at least pseudo-random, because that makes the key hard for an adversary to guess. (See: cryptanalysis, brute force attack.) 🎲

Cryptographic Message Syntax (CMS) 📦 (I) A encapsulation syntax for digital signatures, hashes, and encryption of arbitrary messages. [R2630]

(C) CMS was derived from PKCS #7. CMS values are specified with ASN.1 and use BER encoding. The syntax permits multiple encapsulation with nesting, permits arbitrary attributes to be signed along with the message content, and supports a variety of architectures for digital certificate-based key management 🎀.

$ cryptographic module

💖 okay so a cryptographic module is a set of hardware, software, firmware, or some combo of those that runs cryptographic logic or processes, including cryptographic algorithms. It lives inside its cryptographic boundary, an explicitly defined contiguous perimeter that sets the physical bounds of the module. 🎀 [FP140]

$ cryptographic system

(I) bestie, this is a set of cryptographic algorithms plus the key management processes that keep those algorithms working in some application context. ✨

(O) "A collection of transformations from plaintext into ciphertext and vice versa [which would exclude digital signature, cryptographic hash, and key agreement algorithms], the particular transformation(s) to be used being selected by keys. The transformations are normally defined by a mathematical algorithm." [X509]

$ cryptographic token

(I) A portable, user-controlled, physical device 🧚 that stores cryptographic information and can maybe do cryptographic functions too. (See: cryptographic card, token.)

(C) A smart token might run some set of cryptographic algorithms, and it might also handle related algorithms and key management functions, like a random number generator. 🌸 A smart cryptographic token may or may not contain a cryptographic module, and it might not be explicitly designed that way.

$ cryptography

(I) The mathematical science of transforming data so its meaning is unintelligible (hiding its semantic content), so any undetected alteration gets prevented, or so unauthorized use gets prevented. 💅 If the transformation is reversible, cryptography also covers restoring the encrypted data to an intelligible form. (See: cryptology, steganography.)

(O) "The discipline which embodies principles, means, and methods for the transformation of data in order to hide its information content, prevent its undetected modification and/or prevent its unauthorized use. . . . Cryptography determines the methods used in encipherment and decipherment." [I7498 Part 2]

$ Cryptoki

See: (secondary definition under) PKCS #11.

$ cryptology

(I) The science that includes both cryptography and cryptanalysis, and sometimes people say it includes steganography too. 🌈

$ cryptonet

(I) A group of system entities that all share a secret cryptographic key for a symmetric algorithm. 🫶

$ cryptoperiod

(I) The time span during which a particular key is authorized to be used in a cryptographic system. (See: key management.)

(C) A cryptoperiod is usually stated in calendar or clock time, but sometimes it's stated as the max amount of data a cryptographic algorithm can process with that key. ⏳ Picking one is a tradeoff between the cost of rekeying and the risk of successful cryptanalysis.

(C) Although we deprecate its prefix, this term is long-established in COMPUSEC usage. (See: crypto) In the context of certificates and public keys, "key lifetime" and "validity period" are often used instead. 🙈

$ cryptosystem

(D) ISDs SHOULD NOT use this term as an abbreviation for cryptographic system. (For rationale, see: crypto.) 🚫

$ CSIRT

See: computer security incident response team.

$ CSOR

See: Computer Security Objects Register.

$ cut-and-paste attack

(I) An active attack on the data integrity of ciphertext 😭 where sections of ciphertext get swapped out for other ciphertext. The result looks like it decrypts correctly, but it actually decrypts to plaintext the attacker forged to their satisfaction.

$ cyclic redundancy check (CRC)

(I) Sometimes called "cyclic redundancy code". It's a type of checksum algorithm that is not a cryptographic hash, but it's used for data integrity where accidental changes to data are expected. 🍓

$ DAC

See: Data Authentication Code, discretionary access control.

$ DASS

See: Distributed Authentication Security Service.

$ data

(I) Information in a specific physical representation, usually a sequence of symbols that have meaning, especially a representation of information that a computer can process or produce. 💜

$ Data Authentication Algorithm

(N) A keyed hash function equivalent to DES cipher block chaining with IV = 0. [A9009]

(D) ISDs SHOULD NOT use the uncapitalized form of this term as a synonym for other kinds of checksums. 👑

$ data authentication code vs. Data Authentication Code (DAC)

(N) Capitalized: "The Data Authentication Code" refers to a U.S. Government standard [FP113] for a checksum that is computed by the Data Authentication Algorithm. (Also known as the ANSI standard Message Authentication Code [A9009].) ✨
(D) Not capitalized: ISDs SHOULD NOT use "data authentication code" as a synonym for another kind of checksum, because this term mixes concepts in a potentially misleading way. (See: authentication code.) Instead, use "checksum", "error detection code", "hash", "keyed hash", "Message Authentication Code", or "protected checksum", depending on what is meant. 🦋

$ data compromise

(I) A security incident where information is exposed to potential unauthorized access, so unauthorized disclosure, alteration, or use of the information may have happened. (See: compromise.) 💀

$ data confidentiality

(I) "The property that information is not made available or disclosed to unauthorized individuals, entities, or processes [i.e., to any unauthorized system entity]." [I7498 Part 2]. (See: data confidentiality service.)

(D) ISDs SHOULD NOT use this term as a synonym for "privacy", which is a different concept. 🙅‍♀️

$ data confidentiality service

(I) A security service that protects data against unauthorized disclosure. (See: data confidentiality.)

(D) ISDs SHOULD NOT use this term as a synonym for "privacy", which is a different concept. 🎀

$ Data Encryption Algorithm (DEA)

(N) A symmetric block cipher, defined as part of the U.S. Government's Data Encryption Standard. DEA uses a 64-bit key, of which 56 bits are independently chosen and 8 are parity bits, and it maps a 64-bit block into another 64-bit block. [FP046] (See: DES, symmetric cryptography.)

(C) This algorithm is usually called "DES". It has also been adopted in standards outside the Government (e.g., [A3092]). 🧁

$ data encryption key (DEK)

(I) A cryptographic key that is used to encipher application data. (See: key-encrypting key.) 🔐

$ Data Encryption Standard (DES)

(N) A U.S. Government standard [FP046] that specifies the Data Encryption Algorithm and states policy for using the algorithm to protect unclassified, sensitive data. (See: AES, DEA.) 🌟

$ data integrity

(I) The property that data has not been changed, destroyed, or lost in an unauthorized or accidental manner. (See: data integrity service.) 🛡️

(O) "The property that information has not been modified or destroyed in an unauthorized manner." [I7498 Part 2]

(C) This is about the constancy of data values and confidence in them, not about the information those values represent (see: correctness integrity) or about how trustworthy the source of the values is (see: source integrity). 🧠

$ data integrity service

(I) A security service that protects against unauthorized changes to data, both intentional change or destruction and accidental change or loss, by making sure changes to data are detectable. (See: data integrity.) 🔍

(C) A data integrity service can only detect a change and report it to an appropriate system entity. Changes can't be prevented unless the system is perfect (error-free) and no malicious user has access. 😤 However, a system offering data integrity service might also try to correct and recover from changes.

(C) Relationship between data integrity service and authentication services: Although data integrity service is defined separately from data origin authentication service and peer entity authentication service, it's closely related to them. Authentication services depend, by definition, on companion data integrity services. Data origin authentication service verifies that the identity of the original source of a received data unit is as claimed. There can be no such verification if the data unit has been altered. Peer entity authentication service verifies that the identity of a peer entity in a current association is as claimed. There can be no such verification if the claimed identity has been altered. 🫶

$ data origin authentication

(I) "The corroboration that the source of data received is as claimed." [I7498 Part 2] (See: authentication.) 🌸

$ data origin authentication service

(I) A security service that verifies the identity of a system entity claimed to be the original source of received data. (See: authentication, authentication service.) ✅

(C) This service is provided to any system entity that receives or holds the data. Unlike peer entity authentication service, this one is independent of any association between the originator and the recipient, and the data in question may have originated at any time in the past. ⏰

(C) A digital signature mechanism can provide this service, because someone who doesn't know the private key can't forge the correct signature. However, anyone can verify the origin of correctly signed data by using the signer's public key. 🔑

(C) This service is usually bundled with connectionless data integrity service. (See: (relationship between data integrity service and authentication services under) data integrity service.) 📦

$ data privacy

(D) ISDs SHOULD NOT use this term because it mixes concepts in a potentially misleading way. Instead, use either "data confidentiality" or "privacy", depending on what is meant. 🙃

$ data security

(I) The protection of data from disclosure, alteration, destruction, or loss, whether that loss is accidental or intentional but unauthorized. 🔒

$ datagram

(I) "A self-contained, independent entity of data carrying sufficient information to be routed from the source to the destination." [R1983] 🕊️

$ DEA

See: Data Encryption Algorithm.

$ deception

See: (secondary definition under) threat consequence.

$ decipher

(D) ISDs SHOULD NOT use this term as a synonym for "decrypt", except in special circumstances. (See: (usage discussion under) encryption.) 🙊

$ decipherment

(D) ISDs SHOULD NOT use this term as a synonym for "decryption", except in special circumstances. (See: (usage discussion under) encryption.) 🫣

$ decode

(I) Convert encoded data back to its original form of representation. (See: decrypt.)

(D) ISDs SHOULD NOT use this term as a synonym for "decrypt", because that would mix concepts in a potentially misleading way. 💅

decrypt 🔓 (I) Okay so this one is giving restore 💖 It cryptographically brings ciphertext back to the plaintext form it had before encryption. ✨

decryption 🫶 See: (secondary definition under) encryption. bestie, go check that one! 💅

dedicated security mode 🔐 (I) Picture a mode of operation for an information system where everyone has the clearance or authorization, and the need-to-know, for all the data the system handles. The system can handle a single classification level or category of information, or a whole range of levels and categories. [DOD2] 👑

(C) This mode is formally defined in U.S. Department of Defense policy about system accreditation, but people use the term outside the Defense Department and outside the Government too. 🌈

default account 🎀 (I) A system login account (usually accessed with a user name and password) that's already set up in a manufactured system so you can get in the first time it's turned on. 🧚

(C) Sometimes the default user name and password are the same in every copy of the system. Either way, when the system goes into service, the default password should immediately be changed or the default account should be disabled. 🙈 Don't leave the defaults sitting there, babe!

degauss 🧲 (N) Apply a magnetic field to permanently remove, erase, or clear data from a magnetic storage medium, like a tape or disk [NCS25]. Reduce magnetic flux density to zero by applying a reversing magnetic field. ⭐

degausser ⚡ (N) An electrical device that can degauss magnetic storage media. 🔥

DEK 💜 See: data encryption key.

delta CRL 🦋 (I) A partial CRL that only contains entries for X.509 certificates that have been revoked since a prior, base CRL was issued. This method can be used to partition CRLs that get too large and unwieldy. 🍓

denial of service 💀 (I) The prevention of authorized access to a system resource, or the delaying of system operations and functions. (See: availability, critical (resource of a system), flooding.) It's giving "I can't get in and nobody can" energy. 😭

DES 🌸 See: Data Encryption Standard.

dictionary attack 🗝️ (I) An attack that uses a brute-force technique of successively trying all the words in some large, exhaustive list. 🔍

(C) For example, an attack on an authentication service that tries all possible passwords, or an attack on encryption that encrypts some known plaintext phrase with all possible keys, so that the key for any given encrypted message containing that phrase can be found by lookup. 💅

Diffie-Hellman 🌈 (N) A key agreement algorithm published in 1976 by Whitfield Diffie and Martin Hellman [DH76, R2631]. Iconic, honestly. 👑

(C) Diffie-Hellman does key establishment, not encryption. However, the key it produces may be used for encryption, for further key management operations, or for any other cryptography. ✨

(C) The difficulty of breaking Diffie-Hellman is considered to be equal to the difficulty of computing discrete logarithms modulo a large prime. The algorithm is described in [R2631] and [Schn]. In brief, Alice and Bob together pick large integers that satisfy certain mathematical conditions, and then use those integers to each separately compute a public-private key pair. They send each other their public key. Each person uses their own private key and the other person's public key to compute a key, k, that, because of the mathematics of the algorithm, is the same for each of them. Passive wiretapping cannot learn the shared k, because k is not transmitted, and neither are the private keys needed to compute k. 🤯 However, without additional mechanisms to authenticate each party to the other, a protocol based on the algorithm may be vulnerable to a man-in-the-middle attack. 🚨 Not me being scared of the man-in-the-middle!

digest 🍯 See: message digest.

digital certificate 📜 (I) A certificate document in the form of a digital data object (a data object used by a computer), with a computed digital signature value appended that depends on the data object. (See: attribute certificate, capability, public-key certificate.) 💖

(D) ISDs SHOULD NOT use this term to refer to a signed CRL or CKL. Although the recommended definition can be read to include those items, the security community doesn't use the term with those meanings. 🙅‍♀️

digital certification 🎀 (D) ISDs SHOULD NOT use this term as a synonym for "certification", unless the context isn't enough to tell digital certification apart from another kind of certification. In that case it's better to say "public-key certification" or another phrase that shows what is being certified. 💅

digital document 🌸 (I) An electronic data object that represents information originally written in a non-electronic, non-magnetic medium (usually ink on paper), or that is an analogue of a document of that type. 📄

digital envelope ✉️ (I) A digital envelope for a recipient is a combination of (a) encrypted content data (of any kind) and (b) the content encryption key in an encrypted form that's been prepared for the recipient's use. 💌

(C) In ISDs, this term should be defined at the point of first use, because even though it's defined in PKCS #7 and used in S/MIME, it isn't widely established yet. 🧐

(C) Digital enveloping is not just a synonym for implementing data confidentiality with encryption. It's a hybrid encryption scheme that "seals" a message or other data by encrypting the data and sending both it and a protected form of the key to the intended recipient, so that nobody except the intended recipient can "open" the message. In PCKS #7, you first encrypt the data with a symmetric encryption algorithm and a secret key, then encrypt the secret key with an asymmetric encryption algorithm and the public key of the intended recipient. In S/MIME, extra methods are defined for conveying the content encryption key. 🦋 The layers are everything!

Digital ID(service mark) 🪪 (D) ISDs SHOULD NOT use this term as a synonym for "digital certificate", because (a) it's the service mark of a commercial firm, (b) it unnecessarily duplicates the meaning of other, well-established terms, and (c) a certificate isn't always used as authentication information. In some contexts, though, it may help to explain that the key conveyed in a public-key certificate can be used to verify an identity, so the certificate can be thought of as digital identification information. (See: identification information.) 🙄

digital key 🗝️ (C) The adjective "digital" doesn't need to be used with "key" or "cryptographic key", unless the context isn't enough to tell the digital key apart from another kind of key, like a metal key for a door lock. 🔑

digital notary ⭐ (I) Analogous to a notary public. It provides a trusted date-and-time stamp for a document, so someone can later prove the document existed at a point in time. It may also verify the signature(s) on a signed document before applying the stamp. (See: notarization.) Main character energy for documents! 📅

digital signature ✍️ (I) A value computed with a cryptographic algorithm and appended to a data object, in such a way that any recipient of the data can use the signature to verify the data's origin and integrity. (See: data origin authentication service, data integrity service, digitized signature, electronic signature, signer.) 💜

(I) "Data appended to, or a cryptographic transformation of, a data unit that allows a recipient of the data unit to prove the source and integrity of the data unit and protect against forgery, e.g. by the recipient." [I7498 Part 2] 📖

(C) Typically, the data object is first input to a hash function, and then the hash result is cryptographically transformed using a private key of the signer. The final resulting value is called the digital signature of the data object. The signature value is a protected checksum, because the properties of a cryptographic hash ensure that if the data object is changed, the digital signature will no longer match it. The digital signature is unforgeable, because nobody can be certain of correctly creating or changing the signature without knowing the private key of the supposed signer. 🔐

(C) Some digital signature schemes use an asymmetric encryption algorithm (e.g., see: RSA) to transform the hash result. So when Alice needs to sign a message to send to Bob, she can use her private key to encrypt the hash result. Bob gets both the message and the digital signature. Bob can use Alice's public key to decrypt the signature, and then compare the plaintext result to the hash result he computes by hashing the message himself. If the values are equal, Bob accepts the message, because he's certain it's from Alice and arrived unchanged. If the values aren't equal, Bob rejects the message, because either the message or the signature was altered in transit. 🚫

(C) Other digital signature schemes (e.g., see: DSS) transform the hash result with an algorithm (e.g., see: DSA, El Gamal) that can't be directly used to encrypt data. Such a scheme creates a signature value from the hash and provides a way to verify the signature value, but it doesn't provide a way to recover the hash result from the signature value. In some countries, such a scheme may improve exportability and avoid other legal constraints on usage. 🌍

Digital Signature Algorithm (DSA) 🖊️ (N) An asymmetric cryptographic algorithm that produces a digital signature in the form of a pair of large numbers. The signature is computed using rules and parameters so that the identity of the signer and the integrity of the signed data can be verified. (See: Digital Signature Standard.) 🌟

Digital Signature Standard (DSS) 🏛️ (N) The U.S. Government standard [FP186] that specifies the Digital Signature Algorithm (DSA), which involves asymmetric cryptography. 🇺🇸

digital watermarking 💧 (I) Computing techniques for inseparably embedding unobtrusive marks or labels as bits in digital data--text, graphics, images, video, or audio--and for detecting or extracting those marks later. 🎨

(C) The set of embedded bits (the digital watermark) is sometimes hidden, usually imperceptible, and always intended to be unobtrusive. Depending on the technique used, digital watermarking can help prove ownership, control duplication, trace distribution, ensure data integrity, and perform other functions that protect intellectual property rights. [ACM] 🦋

digitized signature 🙈 (D) ISDs SHOULD NOT use this term, because there's no current consensus on its definition. Although it seems to be used mainly for various forms of digitized images of handwritten signatures, the term should be avoided, because it might be confused with "digital signature". 🫠

directory / Directory 📂 See: directory vs. Directory.

Directory Access Protocol (DAP) 🌷 (N) An OSI protocol [X519] for communication between a Directory User Agent (a client) and a Directory System Agent (a server). (See: Lightweight Directory Access Protocol.) 🧚

$ directory vs. Directory 🗂️

(I) Not capitalized: okay so lowercase "directory" is the generic word for a database server or other system that provides information, like a digital certificate or CRL, about an entity whose name is already known. 💖
(I) Capitalized: "Directory" is the specific one and refers to the X.500 Directory. (See: repository.) ✨

$ disaster plan 🙈

(D) A synonym for "contingency plan". For consistency, ISDs SHOULD use "contingency plan" instead of "disaster plan". 💅

$ disclosure (i.e., unauthorized disclosure)

See: (secondary definition under) threat consequence. 🦋

$ discretionary access control (DAC) 👑

(I) This is an access control service that enforces a security policy based on the identity of system entities and their authorizations to access system resources. (See: access control list, identity-based security policy, mandatory access control.)

(C) It's called "discretionary" because an entity might have access rights that let it, by its own volition, enable another entity to access some resource. 🌸

(O) "A means of restricting access to objects based on the identity of subjects and/or groups to which they belong. The controls are discretionary in the sense that a subject with a certain access permission is capable of passing that permission (perhaps indirectly) on to any other subject." [DOD1]

$ disruption

See: (secondary definition under) threat consequence. 🫶

$ Distinguished Encoding Rules (DER) 🧚

(N) A subset of the Basic Encoding Rules that gives exactly one way to represent any ASN.1 value as an octet string [X690].

(C) BER allows more than one way to encode ASN.1, so DER is used in applications that need a unique encoding, like when a digital signature is computed on an ASN.1 value. ✨

$ distinguished name (DN) 🍓

(I) An identifier that uniquely represents an object in the X.500 Directory Information Tree (DIT) [X501]. (See: domain name.)

(C) A DN is a set of attribute values that identify the path leading from the base of the DIT to the object that is named. An X.509 public-key certificate or CRL contains a DN that identifies its issuer, and an X.509 attribute certificate contains a DN or other form of name that identifies its subject. 💜

$ Distributed Authentication Security Service (DASS)

(I) An experimental Internet protocol [R1507] that uses cryptographic mechanisms to provide strong, mutual authentication services in a distributed environment. 🔥

$ distribution point

(I) An X.500 Directory entry or other information source that is named in a v3 X.509 public-key certificate extension as a location from which to obtain a CRL that might list the certificate. 🌈

(C) A v3 X.509 public-key certificate may have a cRLDistributionPoints extension that names places to get CRLs on which the certificate might be listed. A CRL obtained from a distribution point may (a) cover either all reasons for which a certificate might be revoked or only some of the reasons, (b) be issued by either the authority that signed the certificate or some other authority, and (c) contain revocation entries for only a subset of the full set of certificates issued by one CA or (c') contain revocation entries for multiple CAs. 😭

$ DN

See: distinguished name.

$ DNS

See: Domain Name System.

$ DOI

See: Domain of Interpretation.

$ domain 🎀

(I) Security usage: An environment or context that is defined by a security policy, security model, or security architecture to include a set of system resources and the set of system entities that have the right to access the resources. (See: domain of interpretation, security perimeter.)

(I) Internet usage: That part of the Internet domain name space tree [R1034] that is at or below the name that specifies the domain. A domain is a subdomain of another domain if it is contained within that domain. For example, D.C.B.A is a subdomain of C.B.A. (See: Domain Name System.) 🌐

(O) MISSI usage: The domain of a MISSI CA is the set of MISSI users whose certificates are signed by the CA.

(O) OSI usage: An administrative partition of a complex distributed OSI system.

$ domain name 💖

(I) The style of identifier: a sequence of case-insensitive ASCII labels separated by dots (bbn.com.), defined for subtrees in the Internet Domain Name System [R1034] and used in other Internet identifiers. Examples are host names (e.g., rosslyn.bbn.com.), mailbox names (e.g., rshirey@bbn.com.), and URLs (e.g., http://www.rosslyn.bbn.com/foo). (See: distinguished name, domain.)

(C) The domain name space of the DNS is a tree structure in which each node and leaf holds records describing a resource. Each node has a label. The domain name of a node is the list of labels on the path from the node to the root of the tree. The labels in a domain name are printed or read left to right, from the most specific (lowest, farthest from the root) to the least specific (highest, closest to the root). The root's label is the null string, so a complete domain name properly ends in a dot. The top-level domains, those immediately below the root, include COM, EDU, GOV, INT, MIL, NET, ORG, and two-letter country codes (such as US) from ISO-3166. [R1591] (See: country code.) 🍓

$ Domain Name System (DNS)

(I) The main Internet operations database. It is distributed over a collection of servers and used by client software for purposes such as translating a domain name-style host name into an IP address (e.g., rosslyn.bbn.com is 192.1.7.10) and locating a host that accepts mail for some mailbox address. [R1034]

Domain name space and resource records: Specifications for the tree-structured domain name space, and data associated with the names.
Name servers: Programs that hold information about a subset of the tree's structure and data holdings, and also hold pointers to other name servers that can provide information from any part of the tree.
Resolvers: Programs that extract information from name servers in response to client requests; typically, system routines directly accessible to user programs. 🧚

(C) Extensions to the DNS [R2065, R2137, R2536] support (a) key distribution for public keys needed for the DNS and for other protocols, (b) data origin authentication service and data integrity service for resource records, (c) data origin authentication service for transactions between resolvers and servers, and (d) access control of records. 💅

$ domain of interpretation (DOI)

(I) IPsec usage: An ISAKMP/IKE DOI defines payload formats, exchange types, and conventions for naming security-relevant information such as security policies or cryptographic algorithms and modes. ✨

$ dominate

(I) Security level A is said to "dominate" security level B if the hierarchical classification level of A is greater (higher) than or equal to that of B and the nonhierarchical categories of A include all of those of B. 👑

$ dongle

(I) A portable, physical, electronic device that is required to be attached to a computer to enable a particular software program to run. (See: token.) 🔑

(C) A dongle is essentially a physical key used for copy protection of software, because the program will not run unless the matching dongle is attached. When the software runs, it periodically queries the dongle and quits if the dongle does not reply with the proper authentication information. Dongles were originally constructed as an EPROM (erasable programmable read-only memory) to be connected to a serial input-output port of a personal computer. 💀

$ downgrade

(I) Reduce the classification level of information in an authorized manner. 🫶

$ draft RFC

(D) ISDs SHOULD NOT use this term, because the Request for Comment series is archival in nature and does not have a "draft" category. (Instead, see: Internet Draft, Draft Standard (in Internet Standard).) 🙈

$ DSA

See: Digital Signature Algorithm.

$ DSS

See: Digital Signature Standard.

$ dual control

(I) A procedure that uses two or more entities (usually persons) operating in concert to protect a system resource, such that no single entity acting alone can access that resource. (See: no-lone zone, separation of duties, split knowledge.) 🌸

$ dual signature

(D) ISDs SHOULD NOT use this term except when stated as "SET(trademark) dual signature" with the following meaning:

(O) SET usage: A single digital signature that protects two separate messages by including the hash results for both sets in a single encrypted value. [SET2]

(C) Generated by hashing each message separately, concatenating the two hash results, and then hashing that value and encrypting the result with the signer's private key. Done to reduce the number of encryption operations and to enable verification of data integrity without complete disclosure of the data. 🔥

$ EAP

See: Extensible Authentication Protocol

$ eavesdropping

(I) Passive wiretapping done secretly, i.e., without the knowledge of the originator or the intended recipients of the communication. 👀

$ ECB

See: electronic codebook.

$ ECDSA

See: Elliptic Curve Digital Signature Algorithm.

$ economy of mechanism

(I) The principle that each security mechanism should be designed to be as simple as possible, so that the mechanism can be correctly implemented and so that it can be verified that the operation of the mechanism enforces the containing system's security policy. (See: least privilege.) 🧠

$ EDI

See: electronic data interchange.

$ EDIFACT

See: (secondary definition under) electronic data interchange.

$ EE

(D) ISDs SHOULD NOT use this abbreviation because of possible confusion among "end entity", "end-to-end encryption", "escrowed encryption standard", and other terms. 🙅‍♀️

$ EES

See: Escrowed Encryption Standard.

$ El Gamal algorithm 🍑

(N) An algorithm for asymmetric cryptography, invented in 1985 by Taher El Gamal, that is based on the difficulty of calculating discrete logarithms and can be used for both encryption and digital signatures. [ElGa, Schn]

$ electronic codebook (ECB) 💜

(I) A block cipher mode in which a plaintext block is used directly as input to the encryption algorithm and the resultant output block is used directly as ciphertext [FP081].

$ electronic commerce 🌈

(I) General usage: Business conducted through paperless exchanges of information, using electronic data interchange, electronic funds transfer (EFT), electronic mail, computer bulletin boards, facsimile, and other paperless technologies. 💅

(O) SET usage: "The exchange of goods and services for payment between the cardholder and merchant when some or all of the transaction is performed via electronic communication." [SET2] ✨

$ electronic data interchange (EDI) 💌 (I) Computer-to-computer exchange, between trading partners, of business data in standardized document formats. Basically robots swapping paperwork, bestie 🤖📄

(C) EDI formats have been standardized mainly by ANSI X12 and by EDIFACT (EDI for Administration, Commerce, and Transportation). EDIFACT is the international, UN-sponsored standard, mostly used in Europe and Asia. X12 and EDIFACT are merging into one global EDI standard, and that's giving main character energy 🌍✨

$ electronic signature 🫣 (D) ISDs SHOULD NOT use this term because there's no current consensus on what it means. (Instead, see: digital signature.) 🙅‍♀️

$ elliptic curve cryptography (ECC) 🦋 (I) A type of asymmetric cryptography based on the mathematics of groups defined by the points on a curve. Math so pretty it hurts 😭

(C) The most efficient ECC implementation is claimed to be stronger per bit of key (against cryptanalysis using a brute force attack) than any other known form of asymmetric cryptography. Lowkey iconic. ECC runs on different math than the kind used for Diffie-Hellman and the Digital Signature Algorithm. It's based on groups defined by the points on a curve, where the curve is defined by a quadratic equation in a finite field. ECC can be used to build a key agreement algorithm that's an analog of Diffie-Hellman, and a digital signature algorithm that's an analog of DSA. (See: ECDSA.) 💅

$ Elliptic Curve Digital Signature Algorithm (ECDSA) 🔥 (N) A standard [A9062] that is the elliptic curve cryptography analog of the Digital Signature Algorithm. ECC's signing sibling, periodt 👑

$ emanation 📡 (I) A signal (electromagnetic, acoustic, or some other medium) that a system emits, through radiation or conductance, as a consequence (that is, a byproduct) of its operation, and that may contain information. (See: TEMPEST.) The system is leaking vibes without meaning to 🙈

$ emanations security (EMSEC) 🛡️ (I) Physical constraints that prevent information compromise through signals emanated by a system, in particular the application of TEMPEST technology to block electromagnetic radiation. Locking the vibes down, literally 🔒

$ emergency plan 🚨 (D) A synonym for "contingency plan". For consistency's sake, ISDs SHOULD use "contingency plan" instead of "emergency plan". Pick one name and stick with it, bestie 💖

$ EMSEC See: emanations security. 🔗

$ EMV 💳 (I) An abbreviation of "Europay, MasterCard, Visa". It refers to a specification for smart cards used as payment cards, and for related terminals and applications. [EMV1, EMV2, EMV3] Tap and go, no cap ✨

$ Encapsulating Security Payload (ESP) 🎀 (I) An Internet IPsec protocol [R2406] designed to provide a mix of security services, especially data confidentiality service, in the Internet Protocol. (See: Authentication Header.) Yes, this is the protocol that keeps secrets secret 🤫

(C) ESP can be used alone, in combination with the IPsec AH protocol, or in a nested fashion with tunneling. Security services can be provided between a pair of communicating hosts, between a pair of communicating security gateways, or between a host and a gateway. The ESP header is encapsulated by the IP header, and the ESP header encapsulates either the upper layer protocol header (transport mode) or an IP header (tunnel mode). ESP can provide data confidentiality service, data origin authentication service, connectionless data integrity service, an anti-replay service, and limited traffic flow confidentiality. Which services you get depends on where the implementation sits and on the options chosen when the security association is set up. It's a whole buffet 🍓

$ encipher 🙅‍♀️ (D) ISDs SHOULD NOT use this term as a synonym for "encrypt". However, check the usage note under "encryption". 📝

$ encipherment 🙅‍♀️ (D) ISDs SHOULD NOT use this term as a synonym for "encryption", except in special circumstances explained in the usage discussion under "encryption". Only for the special occasions 🎟️

$ encode 🔤 (I) Use a system of symbols to represent information, which might originally have had some other representation. (See: decode.) Think of it like translating, but make it symbols 🧩

(D) ISDs SHOULD NOT use this term as a synonym for "encrypt", because encoding usually isn't meant to hide meaning. Encoding is more like a costume than a locked diary 🎭

$ encrypt 🔐 (I) Cryptographically transform data to produce ciphertext. (See: encryption.) Scrambling the message so only the right person can read it 💜

$ encryption 🔐✨ (I) The cryptographic transformation of data (called "plaintext") into a form (called "ciphertext") that conceals the data's original meaning to keep it from being known or used. If the transformation is reversible, the reversal process is called "decryption", which restores encrypted data to its original state. (See: cryptography.) This is the whole main plot of cryptography, no cap 🦋

(C) Usage note: For this concept, ISDs should use the verb "to encrypt" (and related variations: encryption, decrypt, and decryption). However, because of cultural biases, some international usage, especially in ISO and CCITT standards, avoids "to encrypt" and uses "to encipher" instead (and related variations: encipherment, decipher, decipherment). Different groups, different slang, same vibe 🌸

(O) "The cryptographic transformation of data (see: cryptography) to produce ciphertext." [I7498 Part 2]

(C) Usually the plaintext going into an encryption operation is cleartext. But sometimes the plaintext may be ciphertext that came out of another encryption operation. (See: superencryption.) Layers on layers, bestie 🧅

(C) Encryption and decryption involve a mathematical algorithm for transforming data. Besides the data itself, the algorithm takes one or more control parameters as inputs: (a) a key value that varies the transformation and, in some cases, (b) an initialization value that sets the algorithm's starting state. The ingredients list, basically 🧁

$ encryption certificate 🎫 (I) A public-key certificate that contains a public key intended for encrypting data, rather than for verifying digital signatures or performing other cryptographic functions. It's the key for the secret-keeping job, not the signing job 🗝️

(C) A v3 X.509 public-key certificate may have a "keyUsage" extension that indicates the purpose the certified public key is intended for. Certificates literally tell you what they're for, iykyk 📜

$ end entity 👤 (I) A system entity that is the subject of a public-key certificate and that is using, or is permitted and able to use, the matching private key only for a purpose or purposes other than signing a digital certificate. In other words, an entity that is not a CA. 🙋‍♀️

(D) "A certificate subject which uses its public [sic] key for purposes other than signing certificates." [X509]

(C) ISDs SHOULD NOT use the X.509 definition, because it's misleading and incomplete. First, the X.509 definition should say "private key" instead of "public key", because certificates aren't usefully signed with a public key. Second, it's weak on whether an end entity may use the private key to sign a certificate, meaning whether the subject may be a CA. X.509's authors intended that an end entity certificate is not valid for verifying a signature on an X.509 certificate or X.509 CRL. So the definition would have been better if it said "only for purposes other than signing certificates". Messy, bestie 😤

(C) Despite the problems in the X.509 definition, the term itself is useful for describing applications of asymmetric cryptography. The way X.509 uses it suggests it was meant to be defined, as we've done here, relative to the roles an entity (associated with an OSI end system) plays, or is permitted to play, in asymmetric cryptography applications other than the PKI that supports them. Roles, not vibes 🎭

(C) Whether a subject can play both CA and non-CA roles, with either the same or different certificates, is a matter of policy. (See: certification practice statement.) A v3 X.509 public-key certificate may have a "basicConstraints" extension containing a "cA" value that specifically "indicates whether or not the public key may be used to verify certificate signatures". Policy decides who gets to wear which hat 🎩

$ end system 🖥️ (I) An OSI term for a computer that implements all seven layers of the OSIRM and may attach to a subnetwork. (In the context of the Internet Protocol Suite, it's usually called a "host".) Same thing, different name tag 🏷️

$ end-to-end encryption 🫶 (I) Continuous protection of data flowing between two points in a network. The data is encrypted when it leaves its source, stays encrypted while it passes through any intermediate computers (such as routers), and is only decrypted when it reaches the intended destination. (See: link encryption, wiretapping.) Secret until it's delivered, 100% 🔒💖

(C) When two points are separated by multiple communication links connected by one or more intermediate relays, end-to-end encryption lets the source and destination systems protect their communications without depending on the intermediate systems to do it for them. Trust no middleman 🙅‍♀️

$ end user 🧑‍💻 (I) General usage: A system entity, usually a human, that makes use of system resources, mainly for application purposes rather than system management purposes. The one actually using the app, not running the server 📱

(I) PKI usage: A synonym for "end entity", but "end entity" is the preferred term. 💅

$ entity See: system entity. 🔗

$ entrapment 🪤 (I) "The deliberate planting of apparent flaws in a system for the purpose of detecting attempted penetrations or confusing an intruder about which flaws to exploit." [FP039] (See: honey pot.) It's giving bait-and-trap, and honestly it's a whole mood 🍯

$ ephemeral key ⏳ (I) A public key or private key that is relatively short-lived. (See: session key.) Here today, gone tomorrow, just like the best trends 🌈

$ error detection code 🧾 (I) A checksum designed to detect, but not correct, accidental (that is, unintentional) changes in data. It catches the typo but won't fix it, bestie 🙈

$ Escrowed Encryption Standard (EES) 🗝️ (N) A U.S. Government standard [FP185] that specifies use of a symmetric encryption algorithm (SKIPJACK) and a Law Enforcement Access Field (LEAF) creation method. Together they implement part of a key escrow system that provides for decryption of encrypted telecommunications when interception is lawfully authorized. Very controversial, very much a plot twist 😬

(C) Both SKIPJACK and the LEAF are to be implemented in equipment used to encrypt and decrypt unclassified, sensitive telecommunications data.

$ ESP See: Encapsulating Security Payload. 🔗

$ Estelle 🧪 (N) A language (ISO 9074-1989) for the formal specification of computer network protocols. A spec language for protocols, so extra 🤓

$ evaluated products list 📋 (O) General usage: A list of information system equipment items that have been evaluated against a particular set of criteria, and found to be compliant with them. Gold star list ⭐

(O) U.S. Department of Defense usage: The Evaluated Products List (http://www.radium.ncsc.mil/tpep/epl/) contains items that have been evaluated against the TCSEC by the NCSC, or against the Common Criteria by the NCSC or one of its partner agencies in another country. The List forms Chapter 4 of NSA's "Information Systems Security Products and Services Catalogue". 🇺🇸✨

$ evaluated system 🔍 (I) A system that has been evaluated against security criteria such as the TCSEC or the Common Criteria. Checked, verified, approved 💅

$ expire See: certificate expiration. ⌛

$ exposure See: (secondary definition under) threat consequence. 💀

Extensible Authentication Protocol 🎀 (I) okay so this is a framework that supports multiple, optional authentication mechanisms for PPP, including cleartext passwords, challenge-response, and arbitrary dialog sequences. [R2284]

(C) this one is mainly for a host or router that connects to a PPP network server over switched circuits or dial-up lines 📞

extension 🧩 (I) a data item defined for optional inclusion in a v3 X.509 public-key certificate or a v2 X.509 CRL.

(C) X.509 formats can be extended to attach extra attributes to subjects and public keys, and to manage a certification hierarchy, which is giving organized 🗂️

"Certificate extension": X.509 defines standard extensions that may be included in v3 certificates to provide additional key and security policy information, subject and issuer attributes, and certification path constraints.
"CRL extension": X.509 defines extensions that may be included in v2 CRLs to provide additional issuer key and name information, revocation reasons and constraints, and information about distribution points and delta CRLs.
"Private extension": Additional extensions, each named by an OID, can be locally defined as needed by applications or communities. (See: PKIX private extension, SET private extensions.) 🔐

extranet 🌐 (I) a computer network that an organization uses to carry application data traffic between the organization and its business partners. (See: intranet.)

(C) an extranet can be built securely, either on the Internet or with Internet technology, by constructing it as a VPN. Secure and iconic 💅

fail safe 🛡️ (I) a mode of system termination that automatically leaves system processes and components in a secure state when a failure occurs or is detected in the system.

fail soft 🌤️ (I) selective termination of affected non-essential system functions and processes when a failure occurs or is detected in the system. Only the stuff that isn't essential gets shut down, which is so smart 🧠

failure control 🔧 (I) a methodology used to provide fail-safe or fail-soft termination and recovery of functions and processes when failures are detected or occur in a system. [FP039]

Federal Information Processing Standards (FIPS) 🏛️ (N) the Federal Information Processing Standards Publication (FIPS PUB) series issued by the U.S. National Institute of Standards and Technology as technical guidelines for U.S. Government procurements of information processing system equipment and services. [FP031, FP039, FP046, FP081, FP102, FP113, FP140, FP151, FP180, FP185, FP186, FP188]

(C) issued under the provisions of section 111(d) of the Federal Property and Administrative Services Act of 1949 as amended by the Computer Security Act of 1987, Public Law 100-235. 📜

Federal Public-key Infrastructure (FPKI) 🇺🇸 (N) a PKI being planned to establish facilities, specifications, and policies needed by the U.S. Federal Government to use public-key certificates for INFOSEC, COMSEC, and electronic commerce involving unclassified but sensitive applications and interactions between Federal agencies as well as with entities of other branches of the Federal Government, state, and local governments, business, and the public. [FPKI]

Federal Standard 1027 🗃️ (N) an U.S. Government document defining emanation, anti-tamper, security fault analysis, and manual key management criteria for DES encryption devices, primary for OSI layer 2. It was renamed "FIPS PUB 140" when responsibility for protecting unclassified, sensitive information was transferred from NSA to NIST, and then was superseded by FIPS PUB 140-1. The glow-up path is wild 🦋

File Transfer Protocol (FTP) 📁 (I) a TCP-based, application-layer, Internet Standard protocol [R0959] for moving data files from one computer to another.

filtering router 🚧 (I) an internetwork router that selectively prevents the passage of data packets according to a security policy.

(C) a filtering router may be used as a firewall or as part of a firewall. A router usually receives a packet from a network and decides where to forward it on a second network. A filtering router does the same, but first decides whether the packet should be forwarded at all, according to some security policy. The policy is implemented by rules (packet filters) loaded into the router. The rules mostly involve values of data packet control fields (especially IP source and destination addresses and TCP port numbers). [R2179]

financial institution 🏦 (N) "An establishment responsible for facilitating customer-initiated transactions or transmission of funds for the extension of credit or the custody, loan, exchange, or issuance of money." [SET2]

fingerprint 🫆 (I) a pattern of curves formed by the ridges on a fingertip. (See: biometric authentication, thumbprint.)

(D) ISDs SHOULD NOT use this term as a synonym for "hash result" because it mixes concepts in a potentially misleading way. Not the vibe 🙅

(D) ISDs SHOULD NOT use this term with the following PGP definition, because the term and definition mix concepts in a potentially misleading way and duplicate the meaning of "hash result":

(O) PGP usage: A hash result used to authenticate a public key (key fingerprint) or other data. [PGP]

FIPS 🔗 See: Federal Information Processing Standards.

FIPS PUB 140-1 🔐 (N) the U.S. Government standard [FP140] for security requirements to be met by a cryptographic module used to protect unclassified information in computer and communication systems. (See: Common Criteria, FIPS, Federal Standard 1027.)

(C) the standard specifies four increasing levels (from "Level 1" to "Level 4") of requirements to cover a wide range of potential applications and environments. The requirements address basic design and documentation, module interfaces, authorized roles and services, physical security, software security, operating system security, key management, cryptographic algorithms, electromagnetic interference and electromagnetic compatibility (EMI/EMC), and self-testing. NIST and the Canadian Communication Security Establishment jointly certify modules. Level up, periodt 📈

firewall 🔥 (I) an internetwork gateway that restricts data communication traffic to and from one of the connected networks (the one said to be "inside" the firewall) and thus protects that network's system resources against threats from the other network (the one that is said to be "outside" the firewall). (See: guard, security gateway.)

(C) a firewall typically protects a smaller, secure network (such as a corporate LAN, or even just one host) from a larger network (such as the Internet). The firewall is installed at the point where the networks connect, and it applies security policy rules to control traffic that flows in and out of the protected network. Bodyguard energy 💪

(C) a firewall is not always a single computer. For example, a firewall may consist of a pair of filtering routers and one or more proxy servers running on one or more bastion hosts, all connected to a small, dedicated LAN between the two routers. The external router blocks attacks that use IP to break security (IP address spoofing, source routing, packet fragments), while proxy servers block attacks that would exploit a vulnerability in a higher layer protocol or service. The internal router blocks traffic from leaving the protected network except through the proxy servers. The difficult part is defining criteria by which packets are denied passage through the firewall, because a firewall not only needs to keep intruders out, but usually also needs to let authorized users in and out. It's a balancing act, bestie 🤹

firmware 💾 (I) computer programs and data stored in hardware, typically in read-only memory (ROM) or programmable read-only memory (PROM), such that the programs and data cannot be dynamically written or modified during execution of the programs. (See: hardware, software.)

FIRST 🔗 See: Forum of Incident Response and Security Teams.

flaw hypothesis methodology 🕵️‍♀️ (I) an evaluation or attack technique in which specifications and documentation for a system are analyzed to hypothesize flaws in the system. The list of hypothetical flaws is prioritized on the basis of the estimated probability that a flaw exists and, assuming it does, on the ease of exploiting it and the extent of control or compromise it would provide. The prioritized list is used to direct a penetration test or attack against the system. [NCS04]

flooding 🌊 (I) an attack that attempts to cause a failure in (especially, in the security of) a computer system or other data processing entity by providing more input than the entity can process properly. (See: denial of service.) Way too much input, not the move 🙃

flow analysis 🔍 (I) an analysis performed on a nonprocedural formal system specification that locates potential flows of information between system variables. By assigning security levels to the variables, the analysis can find some types of covert channels.

flow control 🚦 (I) a procedure or technique to ensure that information transfers within a system are not made from one security level to another security level, and especially not from a higher level to a lower level. (See: covert channel, simple security property, confinement property.)

formal specification 📐 (I) a specification of hardware or software functionality in a computer-readable language; usually a precise mathematical description of the behavior of the system with the aim of providing a correctness proof.

formulary 🧾 (I) a technique for enabling a decision to grant or deny access to be made dynamically at the time the access is attempted, rather than earlier when an access control list or ticket is created.

FORTEZZA(trademark) 💳 (N) a registered trademark of NSA, used for a family of interoperable security products that implement a NIST/NSA-approved suite of cryptographic algorithms for digital signature, hash, encryption, and key exchange. The products include a PC card that contains a CAPSTONE chip, serial port modems, server boards, smart cards, and software implementations.

Forum of Incident Response and Security Teams (FIRST) 🦸 (N) an international consortium of CSIRTs that work together to handle computer security incidents and promote preventive activities. (See: CSIRT, security incident.)

Provide members with technical information, tools, methods, assistance, and guidance.
Coordinate proactive liaison activities and analytical support.
Encourage development of quality products and services.
Improve national and international information security for government, private industry, academia, and the individual.
Enhance the image and status of the CSIRT community. 🫶

forward secrecy 🙈 See: public-key forward secrecy.

FPKI 🔗 See: Federal Public-Key Infrastructure.

FTP 🔗 See: File Transfer Protocol.

$ gateway 🚪

(I) So a gateway is a relay that hooks onto two (or more) computer networks that do similar jobs but are built differently, and it lets hosts on one network talk to hosts on the other. Basically it's an intermediate system that's the interface between two computer networks ✨ (See: bridge, firewall, guard, internetwork, proxy server, router, and subnetwork.)

(C) In theory, gateways are conceivable at any OSI layer 🤓. In practice, they operate at OSI layer 3 (see: bridge, router) or layer 7 (see: proxy server). When the two networks differ in the protocol by which they offer service to hosts, the gateway may translate one protocol into another or otherwise facilitate interoperation of hosts (see: Internet Protocol) 💅.

$ GCA 🎀

See: geopolitical certificate authority.

$ GeneralizedTime ⏰

(N) The ASN.1 data type "GeneralizedTime" (specified in ISO 8601) is giving calendar date (YYYYMMDD) plus a time of day 📅. That time can be (a) the local time, (b) the Coordinated Universal Time, or (c) both the local time and an offset so Coordinated Universal Time can be calculated 🌍. (See: Coordinated Universal Time, UTCTime.)

$ Generic Security Service Application Program Interface (GSS-API) 🔐

(I) This is an Internet Standard protocol [R2078] that spells out calling conventions. An application (usually another communication protocol) can use it to get authentication, integrity, and confidentiality security services, without caring about the underlying security mechanisms and technologies. The big payoff is that the application source code can be ported to different environments, which is so iconic 🫶.

(C) "A GSS-API caller accepts tokens provided to it by its local GSS-API implementation and transfers the tokens to a peer on a remote system; that peer passes the received tokens to its local GSS-API implementation for processing. The security services available through GSS-API in this fashion are implementable (and have been implemented) over a range of underlying mechanisms based on [symmetric] and [asymmetric cryptography]." [R2078]

$ geopolitical certificate authority (GCA) 🗺️

(O) SET usage: in a SET certification hierarchy, this is an optional level that's certified by a BCA and that may certify cardholder CAs, merchant CAs, and payment gateway CAs 💳. Using GCAs lets a brand spread out the responsibility for managing certificates across geographic or political regions, so brand policies can vary between regions as needed 🌏.

$ Green Book 📗

(D) Except as an explanatory appositive, ISDs SHOULD NOT use this term as a synonym for "Defense Password Management Guideline" [CSC2]. Instead, use the full proper name of the document or, in subsequent references, a conventional abbreviation. (See: Rainbow Series.) 🙅‍♀️

(D) Usage note: so we can keep Internet Standards and the Internet Standards Process understandable around the world 🌐, ISDs SHOULD NOT use "cute" synonyms for document titles. No matter how popular and clearly understood a nickname is in one community, it's likely to cause confusion in others 😬. For example, several other information system standards are also called "the Green Book". Some examples:

Each volume of 1992 ITU-T (at that time, CCITT) standards.
"PostScript Language Program Design", Adobe Systems, Addison-Wesley, 1988.
IEEE 1003.1 POSIX Operating Systems Interface.
"Smalltalk-80: Bits of History, Words of Advice", Glenn Krasner, Addison-Wesley, 1983.
"X/Open Compatibility Guide".
A particular CD-ROM format developed by Phillips.

$ GRIP 🛡️

(I) This is short for "Guidelines and Recommendations for Security Incident Processing", the name of the IETF working group that wants to help the Internet community handle security incidents in a consistent way 🫧. (See: security incident.)

(C) The guidelines the WG produces will be aimed at technology vendors, network service providers, and response teams, in their roles helping organizations resolve security incidents 🧑‍💻. These relationships are functional, and they can exist within and across organizational boundaries 🦋.

$ GSS-API 🔐

See: Generic Security Service Application Program Interface.

$ guard 🏰

(I) A gateway that sits between two networks (or computers, or other information systems) operating at different security levels (one level is usually higher than the other) 🥇. It's trusted to mediate all information transfers between the two levels, either to make sure no sensitive information from the first (higher) level gets disclosed to the second (lower) level, or to protect the integrity of data on the first (higher) level 🔒. (See: firewall.)

$ guest login 👋

See: anonymous login.

$ GULS 🧩

(I) This is the Generic Upper Layer Security service element (ISO 11586), a five-part standard for exchanging security information and security-transformation functions that protect the confidentiality and integrity of application data 💜.

$ hacker 💻

(I) Someone with a strong interest in computers, who enjoys learning about them and experimenting with them 🧠. (See: cracker.)

(C) The recommended definition is the original meaning of the term (circa 1960), which had a neutral or positive connotation of "someone who figures things out and makes something cool happen" ✨. Today the term gets misused a lot, especially by journalists, to mean the pejorative meaning of cracker 🙄. Not me being pedantic, just lowkey iykyk.

$ handle 🎧

(I) (1.) Verb: Perform processing operations on data, such as receive and transmit, collect and disseminate, create and delete, store and retrieve, read and write, and compare. (2.) Noun: An on-line pseudonym, particularly one used by a cracker; derived from citizens band radio culture 📻.

$ hardware 🔧

(I) The material physical components of a computer system 🖥️. (See: firmware, software.)

$ hardware token 🪙

See: token.

$ hash code 🚫

(D) ISDs SHOULD NOT use this term (especially not as a synonym for "hash result") because it mixes concepts in a potentially misleading way 🥴. A hash result is not a "code" in any sense defined by this glossary. (See: code, hash result, hash value, message digest.)

$ hash function 🧮

(I) An algorithm that computes a value based on a data object (such as a message or file; usually variable-length; possibly very large). It maps the data object to a smaller data object (the "hash result"), which is usually a fixed-size value 📦. (See: checksum, keyed hash.)

(O) "A (mathematical) function which maps values from a large (possibly very large) domain into a smaller range. A 'good' hash function is such that the results of applying the function to a (large) set of values in the domain will be evenly distributed (and apparently at random) over the range." [X509]

(C) The kind of hash function that security applications need is called a "cryptographic hash function" 🔑. It's an algorithm where it's computationally infeasible (because no attack is significantly more efficient than brute force) to find either (a) a data object that maps to a pre-specified hash result (the "one-way" property) or (b) two data objects that map to the same hash result (the "collision-free" property) 🙅. (See: MD2, MD4, MD5, SHA-1.)

(C) A cryptographic hash is "good" in the sense stated in the "O" definition for hash function 🌸. Any change to an input data object will, with high probability, result in a different hash result, so the result of a cryptographic hash makes a good checksum for a data object 💖.

$ hash result 🍓

(I) The output of a hash function. (See: hash code, hash value.)

(O) "The output produced by a hash function upon processing a message" (where "message" is broadly defined as "a digital representation of data"). [ABA] (The recommended definition is compatible with this ABA definition, but we avoid the unusual definition of "message".) 📝

$ hash value 🫠

(D) ISDs SHOULD NOT use this term (especially not as a synonym for "hash result", the output of a hash function) because it might be confused with "hashed value" (the input to a hash function) 😵‍💫. (See: hash code, hash result, message digest.)

$ hierarchical PKI 🌳

(I) A PKI architecture based on a certification hierarchy 👑. (See: mesh PKI, trust-file PKI.)

$ hierarchy management 📋

(I) The process of generating configuration data and issuing public-key certificates to build and operate a certification hierarchy 🛠️.

$ hierarchy of trust 🙈

(D) ISDs SHOULD NOT use this term with regard to PKI, especially not as a synonym for "certification hierarchy", because this term mixes concepts in a potentially misleading way 🌀. (See: certification hierarchy, trust, web of trust.)

$ hijack attack 🏴‍☠️

(I) A form of active wiretapping in which the attacker seizes control of a previously established communication association 😱. (See: man-in-the-middle attack, pagejacking, piggyback attack.)

$ HMAC 🔏

(I) A keyed hash [R2104] that can be based on any iterated cryptographic hash (e.g., MD5 or SHA-1). So the cryptographic strength of HMAC depends on the properties of the selected cryptographic hash 💪. (See: [R2202, R2403, R2404].)

(C) Assume that H is a generic cryptographic hash in which a function is iterated on data blocks of length B bytes. L is the length of the of hash result of H. K is a secret key of length L <= K <= B. The values IPAD and OPAD are fixed strings used as inner and outer padding, and they're defined like this: IPAD = the byte 0x36 repeated B times and OPAD = the byte 0x5C repeated B times. HMAC is computed by:

H(K XOR OPAD, H(K XOR IPAD, inputdata))

To use available cryptographic hash functions without modification, particularly functions that perform well in software and for which software is freely and widely available.
To preserve the original performance of the selected hash without significant degradation.
To use and handle keys in a simple way.
To have a well-understood cryptographic analysis of the strength of the mechanism based on reasonable assumptions about the underlying hash function.
To enable easy replacement of the hash function in case a faster or stronger hash is found or required.

$ honey pot 🍯

(I) A system (e.g., a web server) or a system resource (e.g., a file on a server) that's designed to be attractive to potential crackers and intruders, like honey is attractive to bears 🐻. (See: entrapment.)

(D) It is likely that other cultures have different metaphors for this concept. To ensure international understanding, ISDs should not use this term unless they also provide an explanation like this one. (See: (usage note under) Green Book.) 🌍

Heads up: the honey pot entry is a good reminder that metaphors don't always travel well across cultures 🫶.

$ host 🖥️

(I) General computer network usage: A computer that is attached to a communication subnetwork or internetwork and can use services provided by the network to exchange data with other attached systems 📡. (See: end system.)

Okay so the host entry keeps going 💻

(I) Specific Internet Protocol Suite usage: a host is a networked computer that does not forward Internet Protocol packets that are not addressed to the computer itself 🙅‍♀️ (See: router.)

(C) Derivation: from the user's side, a host "entertains" guests, providing application layer services or access to other computers attached to the network 🎀 Even though some traditional peripheral service devices, like printers, can now be independently connected to networks, they are not usually called hosts 🖨️

HTML — See: Hypertext Markup Language. 📄

HTTP — See: Hypertext Transfer Protocol. 🌐

https

(I) When used in the first part of a URL (the part that precedes the colon and specifies an access scheme or protocol), this term specifies the use of HTTP enhanced by a security mechanism, which is usually SSL. (See: S-HTTP.) 🔐

hybrid encryption

(I) An application of cryptography that combines two or more encryption algorithms, particularly a combination of symmetric and asymmetric encryption. (E.g., see: digital envelope.) 🫶

(C) Asymmetric algorithms require more computation than equivalently strong symmetric ones. Thus, asymmetric encryption is not normally used for data confidentiality except in distributing symmetric keys in applications where the key data is usually short (in terms of bits) compared to the data it protects. (E.g., see: MSP, PEM, PGP.) 🔑

hyperlink

(I) In hypertext or hypermedia, an information object (such as a word, a phrase, or an image; usually highlighted by color or underscoring) that points (indicates how to connect) to related information that is located elsewhere and can be retrieved by activating the link (e.g., by selecting the object with a mouse pointer and then clicking). 🖱️✨

hypermedia

(I) A generalization of hypertext; any media that contain hyperlinks that point to material in the same or another data object. 🎬

hypertext

(I) A computer document, or part of a document, that contains hyperlinks to other documents; i.e., text that contains active pointers to other text. Usually written in Hypertext Markup Language and accessed using a web browser. (See: hypermedia.) 🕸️

Hypertext Markup Language (HTML)

(I) A platform-independent system of syntax and semantics for adding characters to data files (particularly text files) to represent the data's structure and to point to related data, thus creating hypertext for use in the World Wide Web and other applications. [R1866] 🧁

Hypertext Transfer Protocol (HTTP)

(I) A TCP-based, application-layer, client-server, Internet protocol [R2616] used to carry data requests and responses in the World Wide Web. (See: hypertext.) 📬

IAB — See: Internet Architecture Board. 🏛️

IANA — See: Internet Assigned Numbers Authority. 🔢

ICANN — See: Internet Corporation for Assigned Names and Numbers. 🌍

ICMP — See: Internet Control Message Protocol. 📣

ICMP flood

(I) A denial of service attack that sends a host more ICMP echo request ("ping") packets than the protocol implementation can handle. (See: flooding, smurf.) 🌊💀

ICRL — See: indirect certificate revocation list. 📜

IDEA — See: International Data Encryption Algorithm. 🔐

identification

(I) An act or process that presents an identifier to a system so that the system can recognize a system entity and distinguish it from other entities. (See: authentication.) 🪪

Identification Protocol

(I) An client-server Internet protocol [R1413] for learning the identity of a user of a particular TCP connection. 🕵️‍♀️

(C) Given a TCP port number pair, the server returns a character string that identifies the owner of that connection on the server's system. The protocol is not intended for authorization or access control. At best, it provides additional auditing information with respect to TCP. 📋

identity-based security policy

(I) "A security policy based on the identities and/or attributes of users, a group of users, or entities acting on behalf of the users and the resources/objects being accessed." [I7498 Part 2] (See: rule-based security policy.) 👑

IEEE — See: Institute of Electrical and Electronics Engineers, Inc. ⚡

IEEE 802.10

(N) An IEEE committee developing security standards for local area networks. (See: SILS.) 🏠

IEEE P1363

(N) An IEEE working group, Standard for Public-Key Cryptography, developing a comprehensive reference standard for asymmetric cryptography. Covers discrete logarithm (e.g., DSA), elliptic curve, and integer factorization (e.g., RSA); and covers key agreement, digital signature, and encryption. 🧮

IESG — See: Internet Engineering Steering Group. 🗂️

IETF — See: Internet Engineering Task Force. 🛠️

IKE — See: IPsec Key Exchange. 🗝️

IMAP4 — See: Internet Message Access Protocol, version 4. 📥

IMAP4 AUTHENTICATE

(I) A IMAP4 "command" (better described as a transaction type, or a protocol-within-a-protocol) by which an IMAP4 client optionally proposes a mechanism to an IMAP4 server to authenticate the client to the server and provide other security services. (See: POP3.) 🙋‍♀️

(C) If the server accepts the proposal, the command is followed by performing a challenge-response authentication protocol and, optionally, negotiating a protection mechanism for subsequent POP3 interactions. The security mechanisms that are used by IMAP4 AUTHENTICATE--including Kerberos, GSSAPI, and S/Key--are described in [R1731]. 🧩

in the clear

(I) Not encrypted. (See: cleartext.) 👀

indirect certificate revocation list (ICRL)

(I) In X.509, a CRL that may contain certificate revocation notifications for certificates issued by CAs other than the issuer of the ICRL. 📃

indistinguishability

(I) An attribute of an encryption algorithm that is a formalization of the notion that the encryption of some string is indistinguishable from the encryption of an equal-length string of nonsense. 🫠

information

(I) Facts and ideas, which can be represented (encoded) as various forms of data. 💡

Information Technology Security Evaluation Criteria (ITSEC)

(N) Standard developed for use in the European Union; accommodates a wider range of security assurance and functionality combinations than the TCSEC. Superseded by the Common Criteria. [ITSEC] 🇪🇺

INFOSEC

(I) Abbreviation for "information security", referring to security measures that implement and assure security services in computer systems (i.e., COMPUSEC) and communication systems (i.e., COMSEC). 🛡️

initialization value (IV)

(I) An input parameter that sets the starting state of a cryptographic algorithm or mode. (Sometimes called "initialization vector" or "message indicator".) 🌱

(C) An IV can be used to introduce cryptographic variance in addition to that provided by a key (see: salt), and to synchronize one cryptographic process with another. For an example of the latter, cipher block chaining mode requires an IV. [R2405] 🔁

initialization vector

(D) For consistency, ISDs SHOULD NOT use this term as a synonym for "initialization value". 🙅‍♀️

insider attack — See: (secondary definition under) attack. 🕵️

Institute of Electrical and Electronics Engineers, Inc. (IEEE)

(N) The IEEE is a not-for-profit association of more than 330,000 individual members in 150 countries. The IEEE produces 30 percent of the world's published literature in electrical engineering, computers, and control technology; holds annually more than 300 major conferences; and has more than 800 active standards with 700 under development. (See: Standards for Interoperable LAN/MAN Security.) 🌟

integrity — See: data integrity, correctness integrity, source integrity, system integrity. 💖

integrity check

(D) ISDs SHOULD NOT use this term as a synonym for "cryptographic hash" or "protected checksum", because this term unnecessarily duplicates the meaning of other, well-established terms. 🙅‍♀️

intelligent threat

(I) A circumstance in which an adversary has the technical and operational capability to detect and exploit a vulnerability and also has the demonstrated, presumed, or inferred intent to do so. (See: threat.) 😈

International Data Encryption Algorithm (IDEA)

(N) A patented, symmetric block cipher that uses a 128-bit key and operates on 64-bit blocks. [Schn] (See: symmetric cryptography.) 🧱

International Standard — See: (secondary definition under) ISO. 📚

International Traffic in Arms Regulations (ITAR)

(N) Rules issued by the U.S. State Department, by authority of the Arms Export Control Act (22 U.S.C. 2778), to control export and import of defense articles and defense services, including information security systems, such as cryptographic systems, and TEMPEST suppression technology. (See: Wassenaar Arrangement.) 🛂

internet — See: internet vs. Internet. 🌐

Internet — See: internet vs. Internet. 🌐

Internet Architecture Board (IAB)

(I) A technical advisory group of the ISOC, chartered by the ISOC Trustees to provide oversight of Internet architecture and protocols and, in the context of Internet Standards, a body to which decisions of the IESG may be appealed. Responsible for approving appointments to the IESG from among nominees submitted by the IETF nominating committee. [R2026] 🏛️✨

Internet Assigned Numbers Authority (IANA)

(I) From the early days of the Internet, the IANA was chartered by the ISOC and the U.S. Government's Federal Network Council to be the central coordination, allocation, and registration body for parameters for Internet protocols. Superseded by ICANN. 📒

Internet Control Message Protocol (ICMP)

(I) An Internet Standard protocol [R0792] that is used to report error conditions during IP datagram processing and to exchange other information concerning the state of the IP network. 📡

Internet Corporation for Assigned Names and Numbers (ICANN)

(I) The non-profit, private corporation that has assumed responsibility for the IP address space allocation, protocol parameter assignment, domain name system management, and root server system management functions formerly performed under U.S. Government contract by IANA and other entities. 🌏💜

(C) The Internet Protocol Suite, as defined by the IETF and the IESG, contains numerous parameters, such as internet addresses, domain names, autonomous system numbers, protocol numbers, port numbers, management information base object identifiers, including private enterprise numbers, and many others. The Internet community requires that the values used in these parameter fields be assigned uniquely. ICANN makes those assignments as requested and maintains a registry of the current values. 🗃️🎀

(C) ICANN got formed in October 1998 🌸 by a coalition of the Internet's business, technical, and academic communities. The U.S. Government picked ICANN to be the global consensus entity in charge of coordinating four key functions for the Internet: the allocation of IP address space, the assignment of protocol parameters, the management of the DNS, and the management of the DNS root server system. 👑

Internet Draft

(I) Okay so an Internet Draft is a working document from the IETF, its areas, and its working groups. (Other groups can also put out working documents as Internet Drafts 💅.) Here's the tea: it's not an archival document like an RFC is. It's a preliminary or working doc that's valid for a maximum of six months and can get updated, replaced, or made obsolete by other docs at any time 🫠. Using one as reference material, or citing it as anything other than "work in progress," is inappropriate 🙈.

Internet Engineering Steering Group (IESG)

(I) This is the part of the ISOC that handles the technical management of IETF activities and the administration of the Internet Standards Process, following procedures approved by the ISOC Trustees. It's directly responsible for everything along the "standards track," including final approval of specifications as Internet Standards 🔥. It's made up of IETF Area Directors and the IETF chairperson, who also chairs the IESG. [R2026]

Internet Engineering Task Force (IETF)

(I) A self-organized group of people who contribute to the development of Internet technology 🧚. The principal body developing Internet Standards, although it's not itself a part of the ISOC. It's composed of Working Groups, which are arranged into Areas (such as the Security Area), each coordinated by one or more Area Directors. Nominations to the IAB and the IESG are made by a committee picked at random from regular IETF meeting attendees who've volunteered 🎀. [R2026, R2323]

Internet Message Access Protocol, version 4 (IMAP4)

(I) An Internet protocol [R2060] that lets a client workstation dynamically access a mailbox on a server host to manipulate and retrieve mail messages the server has received and is holding for the client 💌. (See: POP3.)

(C) IMAP4 has mechanisms for optionally authenticating a client to a server and providing other security services 🔐. (See: IMAP4 AUTHENTICATE.)

Internet Policy Registration Authority (IPRA)

(I) An X.509-compliant CA that's the top CA of the Internet certification hierarchy, operated under the auspices of the ISOC [R1422]. (See: (PEM usage under) certification hierarchy.) 🦋

Internet Protocol (IP)

(I) A Internet Standard protocol (version 4 [R0791] and version 6 [R2460]) that moves datagrams (discrete sets of bits) from one computer to another across an internetwork. It does not provide reliable delivery, flow control, sequencing, or the other end-to-end services that TCP provides 🍓. (See: IP address, TCP/IP.)

Internet Protocol Security (IPsec)

(I) Okay, this one's got two meanings. (1.) The name of the IETF working group that's specifying a security architecture [R2401] and protocols to provide security services for Internet Protocol traffic. (2.) A collective name for that architecture and set of protocols. (Implementation of IPsec protocols is optional for IP version 4, but mandatory for IP version 6.) (See: Internet Protocol Security Option.) 🛡️

(C) The IPsec architecture specifies (a) security protocols (AH and ESP), (b) security associations (what they are, how they work, how they're managed, and associated processing), (c) key management (IKE), and (d) algorithms for authentication and encryption 🗝️. The set of security services includes access control service, connectionless data integrity service, data origin authentication service, protection against replays (detection of the arrival of duplicate datagrams, within a constrained window), data confidentiality service, and limited traffic flow confidentiality 💜.

Internet Protocol Security Option (IPSO)

(I) This refers to one of three types of IP security options, which are fields that can be added to an IP datagram to carry security information about the datagram. (See: IPsec.) 🎀

(D) ISDs SHOULD NOT use this term without a modifier to indicate which of the three types is meant 🙅‍♀️.

"DoD Basic Security Option" (IP option type 130): Defined for use on U.S. Department of Defense common user data networks. It identifies the Defense classification level at which the datagram is to be protected and the protection authorities whose rules apply to the datagram. [R1108]

A "protection authority" is a National Access Program (e.g., GENSER, SIOP-ESI, SCI, NSA, Department of Energy) or Special Access Program that specifies protection rules for transmission and processing of the information contained in the datagram. [R1108]

"DoD Extended Security Option" (IP option type 133): Permits additional security labeling information, beyond what's present in the Basic Security Option, to be supplied in the datagram to meet the needs of registered authorities. [R1108] 🌈
"Common IP Security Option" (CIPSO) (IP option type 134): Designed by TSIG to carry hierarchic and non-hierarchic security labels. (Formerly called "Commercial IP Security Option".) It was published as Internet-Draft [CIPSO] and was not advanced to RFC 🥲.

Internet Protocol Suite

See: (secondary definition under) Internet. 🔗

Internet Security Association and Key Management Protocol (ISAKMP)

(I) An Internet IPsec protocol [R2408] to negotiate, establish, modify, and delete security associations, and to exchange key generation and authentication data. It does this independent of the details of any specific key generation technique, key establishment protocol, encryption algorithm, or authentication mechanism 🔑.

(C) ISAKMP supports negotiation of security associations for protocols at all TCP/IP layers ✨. By centralizing management of security associations, ISAKMP reduces duplicated functionality within each protocol. It can also cut connection setup time by negotiating a whole stack of services at once ⚡. Strong authentication is required on ISAKMP exchanges, and a digital signature algorithm based on asymmetric cryptography is used within ISAKMP's authentication component 💅.

Internet Society (ISOC)

(I) A professional society concerned with Internet development (including technical Internet Standards), with how the Internet is and can be used, and with the social, political, and technical issues that result 🌍. The ISOC Board of Trustees approves appointments to the IAB from among nominees submitted by the IETF nominating committee. [R2026]

Internet Standard

(I) A specification, approved by the IESG and published as an RFC, that's stable and well-understood, technically competent, and has multiple, independent, and interoperable implementations with substantial operational experience. It also enjoys significant public support and is recognizably useful in some or all parts of the Internet 👑. [R2026] (See: RFC.)

(C) The Internet Standards Process is an activity of the ISOC and is organized and managed by the IAB and the IESG 🫶. The process is concerned with all protocols, procedures, and conventions used in or by the Internet, whether or not they're part of the Internet Protocol Suite. The "Internet Standards Track" has three levels of increasing maturity: Proposed Standard, Draft Standard, and Standard 📈. (See: (standards levels under) ISO.)

Internet Standards document (ISD)

(C) In this Glossary, this term refers to an RFC, Internet-Draft, or other item that's produced as part of the Internet Standards Process [R2026]. However, neither the term nor the abbreviation is widely accepted and, therefore, ISDs SHOULD NOT be used unless they're accompanied by an explanation like this 🙈. (See: Internet Standard.)

internet vs. Internet

(I) Not capitalized: a popular abbreviation for "internetwork" 🥰.
(I) Capitalized: "The Internet" is the single, interconnected, worldwide system of commercial, government, educational, and other computer networks that share the set of protocols specified by the IAB [R2026] and the name and address spaces managed by the ICANN 🌐.

(C) The protocol set is named the "Internet Protocol Suite". It's also popularly known as "TCP/IP", because TCP and IP are two of its fundamental components 💖. These protocols enable a user of any one of the networks in the Internet to communicate with, or use services located on, any of the other networks.

(C) Although the Internet does have architectural principles [R1958], no Internet Standard formally defines a layered reference model for the IPS that's similar to the OSIRM 🤓. However, Internet community documents do refer (inconsistently) to layers: application, socket, transport, internetwork, network, data link, and physical. In this Glossary, Internet layers are referred to by name to avoid confusing them with OSIRM layers, which are referred to by number 🔢.

internetwork

(I) A system of interconnected networks; a network of networks. It's usually shortened to "internet". (See: internet vs. Internet.) 🕸️

(C) An internet is usually built using OSI layer 3 gateways to connect a set of subnetworks. When the subnetworks differ in the OSI layer 3 protocol service they provide, the gateways sometimes implement a uniform internetwork protocol (e.g., IP) that operates at the top of layer 3. That hides the underlying heterogeneity from hosts that use communication services provided by the internet. (See: router.) 🧠

intranet

(I) A computer network, especially one based on Internet technology, that an organization uses for its own internal, and usually private, purposes and that's closed to outsiders 🔒. (See: extranet, virtual private network.)

intruder

(I) An entity that gains or attempts to gain access to a system or system resource without having authorization to do so 🚫. (See: cracker.)

intrusion

See: security intrusion. 👀

intrusion detection

(I) A security service that monitors and analyzes system events for the purpose of finding attempts to access system resources in an unauthorized manner, and of providing real-time or near real-time warning of them 🚨.

invalidity date

(N) An X.509 CRL entry extension that "indicates the date at which it is known or suspected that the [revoked certificate's private key] was compromised or that the certificate should otherwise be considered invalid" [X509] 💀.

(C) This date may be earlier than the revocation date in the CRL entry, and it can even be earlier than the date of issue of earlier CRLs. However, the invalidity date is not, by itself, sufficient for purposes of non-repudiation service. For example, to fraudulently repudiate a validly-generated signature, a private key holder could falsely claim that the key was compromised at some time in the past 😤.

IP 💖 See: Internet Protocol.

IP address 🌐 (I) Okay so this is a computer's internetwork address, assigned for use by the Internet Protocol and other protocols.

(C) An IP version 4 [R0791] address is written as four 8-bit numbers separated by periods, and it's giving tidy 🎀 For example, the address of the host named rosslyn.bbn.com is 192.1.7.10.

(C) An IP version 6 [R2373] address is written as x:x:x:x:x:x:x:x, where each "x" is the hexadecimal value of one of the eight 16-bit parts of the address ✨ For example, 1080:0:0:0:8:800:200C:417A and FEDC:BA98:7654:3210:FEDC:BA98:7654:3210 🦋

IP Security Option See: Internet Protocol Security Option.

IPRA See: Internet Policy Registration Authority.

IPsec See: Internet Protocol security.

IPsec Key Exchange (IKE) 🔐 (I) An Internet, IPsec, key-establishment protocol [R2409] (partly based on OAKLEY) that is intended for putting in place authenticated keying material for use with ISAKMP and for other security associations, such as in AH and ESP. Iconic 👑

IPSO See: Internet Protocol Security Option.

ISAKMP See: Internet Security Association and Key Management Protocol.

ISD See: Internet Standards document.

ISO 🌍 (I) International Organization for Standardization, a voluntary, non-treaty, non-government organization, established in 1947, with voting members that are designated standards bodies of participating nations and non-voting observer organizations. (See: ANSI, ITU-T.)

(C) Legally, ISO is a Swiss, non-profit, private organization. ISO and the IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in developing international standards through ISO and IEC technical committees that deal with particular fields of activity. Other international governmental and non-governmental organizations, in liaison with ISO and IEC, also take part. (ANSI is the U.S. voting member of ISO. ISO is a class D member of ITU-T.)

(C) The ISO standards development process has four levels of increasing maturity: Working Draft (WD), Committee Draft (CD), Draft International Standard (DIS), and International Standard (IS). (See: (standards track levels under) Internet Standard.) In information technology, ISO and IEC have a joint technical committee, ISO/IEC JTC 1. DISs adopted by JTC 1 are circulated to national bodies for voting, and publication as an IS requires approval by at least 75% of the national bodies casting a vote. 🗳️

ISOC See: Internet Society.

issue (a digital certificate or CRL) 📜 (I) Generate and sign a digital certificate (or CRL) and, usually, distribute it and make it available to potential certificate users (or CRL users). (See: certificate creation.)

(C) The ABA Guidelines [ABA] explicitly limit this term to certificate creation, and exclude the act of publishing. In general usage, however, "issuing" a digital certificate (or CRL) includes not only certificate creation but also making it available to potential users, such as by storing it in a repository or other directory or otherwise publishing it. 📚

issuer 🎀

(I) "Issuer" of a certificate or CRL: The CA that signs the digital certificate or CRL.

(N) "Issuer" of a payment card: SET usage: "The financial institution or its agent that issues the unique primary account number to the cardholder for the payment card brand." [SET2]

(C) The institution that establishes the account for a cardholder and issues the payment card also guarantees payment for authorized transactions that use the card in accordance with card brand regulations and local legislation. [SET1] 💳

ITAR See: International Traffic in Arms Regulations.

ITSEC See: Information Technology System Evaluation Criteria.

ITU-T 🌐 (N) International Telecommunications Union, Telecommunication Standardization Sector (formerly "CCITT"), a United Nations treaty organization that is composed mainly of postal, telephone, and telegraph authorities of the member countries and that publishes standards called "Recommendations". (See: X.400, X.500.)

(C) The Department of State represents the United States. ITU-T works on many kinds of communication systems. ITU-T cooperates with ISO on communication protocol standards, and many Recommendations in that area are also published as an ISO standard with an ISO name and number. It's a whole lore thing 📖

IV See: initialization value.

KDC See: Key Distribution Center.

KEA See: Key Exchange Algorithm.

KEK See: key-encrypting key.

Kerberos 🐕 (N) A system developed at the Massachusetts Institute of Technology that depends on passwords and symmetric cryptography (DES) to implement ticket-based, peer entity authentication service and access control service distributed in a client-server network environment. [R1510, Stei]

(C) Kerberos was developed by Project Athena and is named for the three-headed dog guarding Hades. Literally the coolest name in networking, no cap 🔥

key See: cryptographic key.

key agreement (algorithm or protocol) 🤝 (I) A key establishment method (especially one involving asymmetric cryptography) by which two or more entities, without prior arrangement except a public exchange of data (such as public keys), each computes the same key value. I.e., each can independently generate the same key value, but that key cannot be computed by other entities. (See: Diffie-Hellman, key establishment, Key Exchange Algorithm, key transport.)

(O) "A method for negotiating a key value on line without transferring the key, even in an encrypted form, e.g., the Diffie-Hellman technique." [X509]

(O) "The procedure whereby two different parties generate shared symmetric keys such that any of the shared symmetric keys is a function of the information contributed by all legitimate participants, so that no party [alone] can predetermine the value of the key." [A9042]

(C) For example, a message originator and the intended recipient can each use their own private key and the other's public key with the Diffie-Hellman algorithm to first compute a shared secret value and, from that value, derive a session key to encrypt the message. 💌

key authentication (N) "The assurance of the legitimate participants in a key agreement that no non-legitimate party possesses the shared symmetric key." [A9042] 🛡️

key center (I) A centralized key distribution process (used in symmetric cryptography), usually a separate computer system, that uses key-encrypting keys (master keys) to encrypt and distribute session keys needed in a community of users.

key confirmation (N) "The assurance of the legitimate participants in a key establishment protocol that the intended parties sharing the symmetric key actually possess the shared symmetric key." [A9042] ✅

key distribution (I) A process that delivers a cryptographic key from the location where it is generated to the locations where it is used in a cryptographic algorithm. (See: key management.) 🚚

key distribution center (KDC) 🏰 (I) A type of key center (used in symmetric cryptography) that implements a key distribution protocol to provide keys (usually, session keys) to two (or more) entities that wish to communicate securely. (See: key translation center.)

(C) A KDC distributes keys to Alice and Bob, who (a) wish to communicate with each other but do not currently share keys, (b) each share a KEK with the KDC, and (c) may not be able to generate or acquire keys by themselves. Alice requests the keys from the KDC. The KDC generates or acquires the keys and makes two identical sets. The KDC encrypts one set in the KEK it shares with Alice, and sends that encrypted set to Alice. The KDC encrypts the second set in the KEK it shares with Bob, and either sends that encrypted set to Alice for her to forward to Bob, or sends it directly to Bob (although the latter option is not supported in the ANSI standard [A9017]). 👭

key encapsulation See: (secondary definition under) key recovery.

key-encrypting key (KEK) 🔑 (I) A cryptographic key that is used to encrypt other keys, either DEKs or other KEKs, but usually is not used to encrypt application data.

key escrow See: (secondary definition under) key recovery.

key establishment (algorithm or protocol) 🧩 (I) A process that combines the key generation and key distribution steps needed to set up or install a secure communication association. (See: key agreement, key transport.)

(O) "The procedure to share a symmetric key among different parties by either key agreement or key transport." [A9042]

Key transport: One entity generates a secret key and securely sends it to the other entity. (Or each entity generates a secret value and securely sends it to the other entity, where the two values are combined to form a secret key.)
Key agreement: No secret is sent from one entity to another. Instead, both entities, without prior arrangement except a public exchange of data, compute the same secret value. I.e., each can independently generate the same value, but that value cannot be computed by other entities.

Key Exchange Algorithm (KEA) 🕵️ (N) A key agreement algorithm [NIST] that is similar to the Diffie-Hellman algorithm, uses 1024-bit asymmetric keys, and was developed and formerly classified at the "Secret" level by NSA. (See: CAPSTONE, CLIPPER, FORTEZZA, SKIPJACK.)

key generation (I) A process that creates the sequence of symbols that comprise a cryptographic key. (See: key management.) ✨

key generator ⚙️

(I) An algorithm that uses mathematical rules to deterministically produce a pseudo-random sequence of cryptographic key values.
(I) An encryption device that incorporates a key generation mechanism and applies the key to plaintext (e.g., by exclusive OR-ing the key bit string with the plaintext bit string) to produce ciphertext.

key length (I) The number of symbols (usually bits) needed to be able to represent any of the possible values of a cryptographic key. (See: key space.) 📏

key lifetime ⏳ (N) MISSI usage: An attribute of a MISSI key pair that specifies a time span that bounds the validity period of any MISSI X.509 public-key certificate that contains the public component of the pair. (See: cryptoperiod.)

$ key management ✨ (I) Okay so key management is basically the whole life story of cryptographic keys and their related material (like initialization values) inside a crypto system. That covers ordering, generating, distributing, storing, loading, escrowing, archiving, auditing, and destroying them 🔐. (See: key distribution, key escrow, keying material, public-key infrastructure.)

(O) Here's how other sources put it: "The generation, storage, distribution, deletion, archiving and application of keys in accordance with a security policy." [I7498 Part 2]

(O) And another one, even more detailed: "The activities involving the handling of cryptographic keys and other related security parameters (e.g., IVs, counters) during the entire life cycle of the keys, including their generation, storage, distribution, entry and use, deletion or destruction, and archiving." [FP140] 💅

$ Key Management Protocol (KMP) 🎀 (N) A protocol for setting up a shared symmetric key between a pair (or a group) of users. (One version of KMP was developed by SDNS, and another by SILS.)

$ key material identifier (KMID) 🏷️ (N) MISSI usage: a 64-bit identifier that gets assigned to a key pair when its public key is bound in a MISSI X.509 public-key certificate.

$ key pair 🔑 (I) A set of mathematically related keys, a public key and a private key, used for asymmetric cryptography. They're generated in a way that makes it computationally infeasible to derive the private key from knowing the public key (e.g., see: Diffie-Hellman, Rivest-Shamir-Adleman). 🧠

(C) The owner of a key pair shares the public key with other system entities so they can encrypt data, verify a digital signature, compute a protected checksum, or generate a key in a key agreement algorithm. The matching private key stays secret with the owner, who uses it to decrypt data, generate a digital signature, verify a protected checksum, or generate a key in a key agreement algorithm. 🫶

$ key recovery 🦋

(I) A process for learning the value of a cryptographic key that was previously used to perform some cryptographic operation. (See: cryptanalysis.)
(I) Techniques that provide an intentional, alternate (i.e., secondary) means to access the key used for data confidentiality service in an encrypted association. [DOD4]

(C) We're assuming the encryption mechanism has a primary way of getting the key through a key establishment algorithm or protocol. For the secondary way, there are two classes of key recovery techniques: key escrow and key encapsulation 🙈

"Key escrow": a key recovery technique for storing knowledge of a cryptographic key, or parts of it, in the custody of one or more third parties called "escrow agents", so the key can be recovered and used in specified circumstances. Key escrow is typically implemented with split knowledge techniques. For example, the Escrowed Encryption Standard [FP185] entrusts two components of a device-unique split key to separate escrow agents. The agents hand over the components only to someone legally authorized to conduct electronic surveillance of telecommunications encrypted by that specific device. The components are used to rebuild the device-unique key, and that key is used to get the session key needed to decrypt communications.
"Key encapsulation": a key recovery technique for storing knowledge of a cryptographic key by encrypting it with another key, and making sure only certain third parties called "recovery agents" can do the decryption to retrieve the stored key. Key encapsulation typically allows direct retrieval of the secret key used to provide data confidentiality.

$ key space 🌈 (I) The range of possible values of a cryptographic key, or the number of distinct transformations supported by a particular cryptographic algorithm. (See: key length.)

$ key translation center 🧚 (I) A type of key center (used in symmetric cryptography) that runs a key distribution protocol to convey keys between two (or more) parties who want to communicate securely. (See: key distribution center.)

(C) A key translation center translates keys for future communication between Bob and Alice. They (a) want to talk to each other but don't share keys yet, (b) each share a KEK with the center, and (c) can generate or acquire keys on their own. Alice generates or acquires a set of keys for talking to Bob, encrypts the set in the KEK she shares with the center, and sends it to the center. The center decrypts the set, re-encrypts it in the KEK it shares with Bob, and then either sends that encrypted set to Alice so she can forward it to Bob, or sends it directly to Bob (although direct distribution isn't supported in the ANSI standard [A9017]). 🍓

$ key transport (algorithm or protocol) 🚚 (I) A key establishment method where a secret key is generated by one entity in a communication association and securely sent to another entity in that association. (See: key agreement.)

(O) Another source says: "The procedure to send a symmetric key from one party to other parties. As a result, all legitimate participants share a common symmetric key in such a way that the symmetric key is determined entirely by one party." [A9042]

(C) For example, a message originator can generate a random session key, then use the Rivest-Shamir-Adleman algorithm to encrypt that key with the public key of the intended recipient. 💌

$ key update 🔄 (I) Derive a new key from an existing key. (See: certificate rekey.)

$ key validation ✅ (N) "The procedure for the receiver of a public key to check that the key conforms to the arithmetic requirements for such a key in order to thwart certain types of attacks." [A9042]

$ keyed hash 🔒 (I) A cryptographic hash (e.g., [R1828]) where the mapping to a hash result is varied by a second input parameter, which is a cryptographic key. (See: checksum.)

(C) If the input data object changes, a new hash result can't be correctly computed without knowing the secret key. So the secret key protects the hash result, which means it can work as a checksum even when there's a threat of an active attack on the data. There are at least two forms of keyed hash: 👑

A function based on a keyed encryption algorithm. (E.g., see: Data Authentication Code.)
A function based on a keyless hash that gets enhanced by combining (e.g., by concatenating) the input data object parameter with a key parameter before mapping to the hash result. (E.g., see: HMAC.)

$ keying material 🗝️ (I) Data (such as keys, key pairs, and initialization values) needed to establish and maintain a cryptographic security association.

$ KMID See: key material identifier.

$ known-plaintext attack 🕵️ (I) A cryptanalysis technique where the analyst tries to figure out the key from knowing some plaintext-ciphertext pairs (although the analyst may also have other clues, such as knowing the cryptographic algorithm). 💀

$ L2F See: Layer 2 Forwarding Protocol.

$ L2TP See: Layer 2 Tunneling Protocol.

$ label See: security label.

$ Language of Temporal Ordering Specification (LOTOS) 📜 (N) A language (ISO 8807-1990) for formally specifying computer network protocols. It describes the order in which events occur.

$ lattice model 🪜 (I) A security model for flow control in a system, based on the lattice formed by the finite security levels in a system and their partial ordering. [Denn] (See: flow control, security level, security model.)

(C) The model describes the semantic structure formed by a finite set of security levels, like the ones used in military organizations.

(C) A lattice is a finite set together with a partial ordering on its elements, such that every pair of elements has a least upper bound and a greatest lower bound. For example, a lattice is formed by a finite set S of security levels (a set S of all ordered pairs (x, c), where x is one of a finite set X of hierarchically ordered classification levels (X1, ..., Xm), and c is a possibly empty subset of a finite set C of non-hierarchical categories (C1, ..., Cn)), together with the "dominate" relation. (See: dominate.) 🧩

$ Law Enforcement Access Field (LEAF) 🚨 (N) A data item that gets automatically embedded in data encrypted by devices (e.g., see: CLIPPER chip) that implement the Escrowed Encryption Standard.

$ Layer 2 Forwarding Protocol (L2F) 🌐 (N) An Internet protocol (originally developed by Cisco Corporation) that uses tunneling of PPP over IP to create a virtual extension of a dial-up link across a network. The dial-up server starts it, and the dial-up user never notices. (See: L2TP.)

$ Layer 2 Tunneling Protocol (L2TP) 🛸 (N) An Internet client-server protocol that combines aspects of PPTP and L2F, and supports tunneling of PPP over an IP network, or over frame relay or another switched network. (See: virtual private network.)

(C) PPP can in turn encapsulate any OSI layer 3 protocol. So L2TP doesn't specify security services. It depends on the protocols layered above and below it to provide whatever security is needed. 🫧

$ LDAP See: Lightweight Directory Access Protocol.

$ least privilege 🥇 (I) The principle that a security architecture should be designed so each system entity gets the minimum system resources and authorizations it needs to do its work. (See: economy of mechanism.)

$ Lightweight Directory Access Protocol (LDAP) 📇 (N) A client-server protocol that supports basic use of the X.500 Directory (or other directory servers) without taking on the resource requirements of the full Directory Access Protocol (DAP). [R1777]

(C) Designed for simple management and browser applications that provide simple read/write interactive directory service. It supports both simple authentication and strong authentication of the client to the directory server. ✨

$ link 🔗 (I) World Wide Web usage: see: hyperlink.

(I) Subnetwork usage: a point-to-point communication channel connecting two subnetwork relays (especially one between two packet switches), implemented at OSI layer 2. (See: link encryption.)

(C) The relay computers assume links are logically passive. If a computer at one end of a link sends a sequence of bits, the sequence simply arrives at the other end after a finite time, although some bits may have been changed either accidentally (errors) or by active wiretapping. 🙀

link-by-link encryption / link encryption

(I) Okay so this is stepwise protection for data zooming between two points in a network 🦋. It gets encrypted separately on each network link, so it's encrypted when it leaves a host or subnetwork relay and decrypted when it reaches the next host or relay. Each link may use a different key or even a different algorithm, which is so extra 💅 [R1455] (See: end-to-end encryption.)

logic bomb

(I) Malicious logic that activates when specified conditions are met 💣. It's usually meant to cause denial of service or otherwise wreck system resources 💀 (See: Trojan horse, virus, worm.)

login

(I) The moment a system entity gets access to a session where it can use system resources 🔑. This usually happens when you type a user name and password into an access control system that checks who you are.

(C) "Login" comes from "log" file, a security audit trail that records security events, like when sessions begin and who started them 📜

LOTOS

See: Language of Temporal Ordering Specification. 🧚

MAC

See: mandatory access control, Message Authentication Code.

malicious logic

(I) Hardware, software, or firmware that's intentionally included or inserted in a system for a harmful purpose 😈 (See: logic bomb, Trojan horse, virus, worm.)

malware

(I) Short for "malicious software". (See: malicious logic.)

(D) ISDs SHOULD NOT use this term because it isn't listed in most dictionaries and could confuse international readers 🌍

man-in-the-middle

(I) An active wiretapping attack where the attacker intercepts and selectively modifies communicated data so it can masquerade as one or more of the entities in a communication association 👀 (See: hijack attack, piggyback attack.)

(C) Picture this: Alice and Bob try to set up a session key with the Diffie-Hellman algorithm, with no data origin authentication service. A "man in the middle" could (a) block direct communication between Alice and Bob, then (b) pretend to be Alice sending data to Bob, (c) pretend to be Bob sending data to Alice, (d) set up separate session keys with each of them, and (e) act as a secret proxy server between them to capture or modify sensitive info that Alice and Bob think they're only sending to each other 🕵

mandatory access control (MAC)

(I) An access control service that enforces a security policy by comparing (a) security labels, which show how sensitive or critical system resources are, with (b) security clearances, which show which system entities are eligible to access certain resources 🔒 (See: discretionary access control, rule-based security policy.)

(C) It's called "mandatory" because an entity that has clearance to access a resource can't just decide on its own to let another entity access that resource 🙅‍♀️

(O) "A means of restricting access to objects based on the sensitivity (as represented by a label) of the information contained in the objects and the formal authorization (i.e., clearance) of subjects to access information of such sensitivity." [DOD1]

manipulation detection code

(D) ISDs SHOULD NOT use this as a synonym for "checksum" 🙈. "Manipulation" implies protection against active attacks, and an ordinary checksum might not provide that. If that protection is intended, use "protected checksum" or some particular type of it, depending on what's meant. If it's not intended, use "error detection code" or some specific type of checksum that isn't protected.

masquerade attack

(I) A type of attack where one system entity illegitimately poses as (assumes the identity of) another entity 🎭 (See: spoofing attack.)

MCA

See: merchant certification authority.

MD2

(N) A cryptographic hash [R1319] that produces a 128-bit hash result. It was designed by Ron Rivest and is similar to MD4 and MD5, but slower 🐢 (See: message digest.)

MD4

(N) A cryptographic hash [R1320] that produces a 128-bit hash result and was designed by Ron Rivest. (See: message digest and SHA-1.)

MD5

(N) A cryptographic hash [R1321] that produces a 128-bit hash result and was designed by Ron Rivest as an improved version of MD4 ✨

merchant

(O) SET usage: "A seller of goods, services, and/or other information who accepts payment for these items electronically." [SET2] A merchant may also provide electronic selling services and/or electronic delivery of items for sale. With SET, the merchant can offer its cardholders secure electronic interactions, but a merchant that accepts payment cards is required to have a relationship with an acquirer. [SET1, SET2] 🛍

merchant certificate

(O) SET usage: A public-key certificate issued to a merchant 📜 Sometimes this refers to a pair of such certificates, where one is for digital signature use and the other is for encryption.

merchant certification authority (MCA)

(O) SET usage: A CA that issues digital certificates to merchants and is operated on behalf of a payment card brand, an acquirer, or another party according to brand rules. Acquirers verify and approve requests for merchant certificates before the MCA issues them. An MCA does not issue a CRL, but it does distribute CRLs issued by root CAs, brand CAs, geopolitical CAs, and payment gateway CAs. [SET2] 💳

mesh PKI

(I) A non-hierarchical PKI architecture with several trusted CAs instead of a single root 🕸 Each certificate user bases path validations on the public key of one of the trusted CAs, usually the one that issued that user's own public-key certificate. There aren't superior-to-subordinate relationships between CAs. Instead, they're peer-to-peer, and CAs issue cross-certificates to each other. (See: hierarchical PKI, trust-file PKI.)

message authentication code vs. Message Authentication Code (MAC)

(N) Capitalized: "(The) Message Authentication Code" refers to an ANSI standard for a checksum that's computed with a keyed hash based on DES. [A9009] (Also known as the U.S. Government standard Data Authentication Code. [FP113])

(D) Not capitalized: ISDs SHOULD NOT use the uncapitalized form "message authentication code", because this term mixes concepts in a potentially misleading way. Instead, use "checksum", "error detection code", "hash", "keyed hash", "Message Authentication Code", or "protected checksum", depending on what's meant. (See: authentication code.) 🤔

(C) In the uncapitalized form, "message" is misleading because it implies the mechanism is especially suited to, or limited to, electronic mail (see: Message Handling Systems). "Authentication" is misleading because the mechanism mainly serves a data integrity function rather than an authentication function. "Code" is misleading because it implies that encoding or encryption is involved, or that the term refers to computer software.

message digest

(D) ISDs SHOULD NOT use this term as a synonym for "hash result" because it needlessly duplicates the meaning of the other, more general term and mixes concepts in a potentially misleading way. (See: cryptographic hash, Message Handling System.)

Message Handling Systems

(I) An ITU-T/ISO system concept that includes the notion of electronic mail but defines more comprehensive OSI systems and services that let users exchange messages on a store-and-forward basis 📬 (The ISO equivalent is "Message Oriented Text Interchange System".) (See: X.400.)

message indicator

(D) ISDs SHOULD NOT use this term as a synonym for "initialization value" because it mixes concepts in a potentially misleading way.

message integrity check / message integrity code

(D) ISDs SHOULD NOT use these terms because they mix concepts in a potentially misleading way. "Message" is misleading because it suggests the mechanism is especially suited to, or limited to, electronic mail. "Code" is misleading because it suggests that encoding or encryption is involved, or that the term refers to computer software. Instead, use "checksum", "error detection code", "hash", "keyed hash", "Message Authentication Code", or "protected checksum", depending on what's meant.

Message Security Protocol (MSP)

(N) A secure message handling protocol [SDNS7] for use with X.400 and Internet mail protocols. It was developed by NSA's SDNS program and is used in the U.S. Defense Message System 🇺🇸

MHS

See: message handling system.

MIME

See: Multipurpose Internet Mail Extensions.

MIME Object Security Services (MOSS)

(I) An Internet protocol [R1848] that applies end-to-end encryption and digital signature to MIME message content. It uses symmetric cryptography for encryption and asymmetric cryptography for key distribution and signature. MOSS is based on features and specifications of PEM. (See: S/MIME.) 🎀

Minimum Interoperability Specification for PKI Components (MISPC)

(N) A technical description that provides a basis for interoperation between PKI components from different vendors. It consists primarily of a profile of certificate and CRL extensions and a set of transactions for PKI operation. [MISPC]

MISPC

See: Minimum Interoperability Specification for PKI Components.

MISSI

(N) Multilevel Information System Security Initiative, an NSA program that encourages development of interoperable, modular products for constructing secure network information systems that support a wide variety of Government missions. (See: MSP.)

MISSI user

(O) MISSI usage: A system entity that is the subject of one or more MISSI X.509 public-key certificates issued under a MISSI certification hierarchy. (See: personality.)

(C) MISSI users include both end users and the authorities that issue certificates. A MISSI user is usually a person but may be a machine or other automated process. Some machines are required to operate non-stop. To avoid downtime for swapping the FORTEZZA cards of machine operators at shift changes, the machines may be issued their own cards, as if they were persons 🤖

mode / mode of operation

(I) Encryption usage: A technique for enhancing the effect of a cryptographic algorithm, or adapting the algorithm for an application, such as applying a block cipher to a sequence of data blocks or a data stream. (See: electronic codebook, cipher block chaining, cipher feedback, output feedback.) 🌸

(I) System operation usage: okay so this is a type of security policy 🔐 that spells out the range of classification levels a system is allowed to handle, plus the range of clearances and authorizations that users are allowed to have to get into it 💅. (See: dedicated security mode, multilevel security mode, partitioned security mode, system high security mode.)

modulus 🎀 (I) The defining constant in modular arithmetic. It's usually part of the public key in asymmetric cryptography that's based on modular arithmetic, so it's literally the main character of that math 👑 (See: Diffie-Hellman, Rivest-Shamir-Adleman.)

Morris Worm 🐛 (I) A worm program written by Robert T. Morris, Jr. that flooded the ARPANET in November, 1988, causing problems for thousands of hosts. 😭 (See: worm.)

MOSS 🌸 See: MIME Object Security Services.

MSP 🦋 See: Message Security Protocol.

multilevel secure (MLS) 🧚 (I) A class of system that has system resources (particularly stored information) at more than one security level, meaning it has different types of sensitive resources. It permits concurrent access by users who differ in security clearance and need-to-know, but it's able to stop each user from getting into resources they aren't authorized for. Iconic behavior, honestly 🔥

multilevel security mode 💜 (I) A mode of operation of an information system that allows two or more classification levels of information to be processed concurrently within the same system, even when not all users have a clearance or formal access authorization for all the data the system handles.

(C) This mode is defined formally in U.S. Department of Defense policy regarding system accreditation [DOD2], but the term is also used outside the Defense Department and outside the Government. ✨

Multipurpose Internet Mail Extensions (MIME) 💌 (I) An Internet protocol [R2045] that enhances the basic format of Internet electronic mail messages [R0822] so it can use character sets other than US-ASCII for textual headers and text content. It can also carry non-textual and multi-part content. (See: S/MIME.) 🌈

mutual suspicion 🙈 (I) The state that exists between two interacting system entities in which neither entity can trust the other to function correctly with regard to some security requirement. Not the vibe, but very real 💀

National Computer Security Center (NCSC) 🛡️ (N) A U.S. Department of Defense organization, housed in NSA, that has responsibility for encouraging widespread availability of trusted computer systems throughout the Federal Government. It has established criteria for, and performs evaluations of, computer and network systems that have a trusted computing base. (See: Evaluated Products List, Rainbow Series, TCSEC.) 🌟

National Information Assurance Partnership (NIAP) 🤝 (N) An organization created by NIST and NSA to enhance the quality of commercial products for information security and increase consumer confidence in those products through objective evaluation and testing methods.

(C) NIAP is registered, through the U.S. Department of Defense, as a National Performance Review Reinvention Laboratory. NIAP functions include the following:

Developing tests, test methods, and other tools that developers and testing laboratories may use to improve and evaluate security products. 🧪
Collaborating with industry and others on research and testing programs.
Using the Common Criteria to develop protection profiles and associated test sets for security products and systems.
Cooperating with the NIST National Voluntary Laboratory Accreditation Program to develop a program to accredit private-sector laboratories for the testing of information security products using the Common Criteria.
Working to establish a formal, international mutual recognition scheme for a Common Criteria-based evaluation. 🌍

National Institute of Standards and Technology (NIST) 📏 (N) A U.S. Department of Commerce agency that promotes U.S. economic growth by working with industry to develop and apply technology, measurements, and standards. It has primary Government responsibility for INFOSEC standards for unclassified but sensitive information. (See: ANSI, DES, DSA, DSS, FIPS, NIAP, NSA.)

National Security Agency (NSA) 🕵️‍♀️ (N) A U.S. Department of Defense intelligence agency that has primary Government responsibility for INFOSEC for classified information and for unclassified but sensitive information handled by national security systems. (See: FORTEZZA, KEA, MISSI, NIAP, NIST, SKIPJACK.)

need-to-know 🗝️ (I) The necessity for access to, knowledge of, or possession of specific information required to carry out official duties.

(C) This criterion is used in security procedures that require a custodian of sensitive information, before disclosing the information to someone else, to establish that the intended recipient has proper authorization to access the information. 💅

network 🕸️ See: computer network.

NIAP 🌼 See: National Information Assurance Partnership.

NIST 🌷 See: National Institute of Standards and Technology.

NLSP 🪄 Network Layer Security Protocol. An OSI protocol (IS0 11577) for end-to-end encryption services at the top of OSI layer 3. NLSP is derived from an SDNS protocol, SP3, but it's way more complex 😵‍💫

no-lone zone 🚪 (I) A room or other space to which no person may have unaccompanied access, and that, when occupied, is required to be occupied by two or more appropriately authorized persons. (See: dual control.)

nonce 🎲 (I) A random or non-repeating value that is included in data exchanged by a protocol, usually for the purpose of guaranteeing liveness and thus detecting and protecting against replay attacks. Tiny value, huge energy 💜

non-critical 🫧 See: critical (extension of certificate).

non-repudiation service 🧾 (I) A security service that provides protection against false denial of involvement in a communication. (See: repudiation.)

(C) Non-repudiation service does not and cannot prevent an entity from repudiating a communication. Instead, the service provides evidence that can be stored and later presented to a third party to resolve disputes that arise if and when a communication is repudiated by one of the entities involved. There are two basic kinds of non-repudiation service:

"Non-repudiation with proof of origin" provides the recipient of data with evidence that proves the origin of the data, and thus protects the recipient against an attempt by the originator to falsely deny sending the data. This service can be viewed as a stronger version of a data origin authentication service, in that it proves authenticity to a third party. 🔏
"Non-repudiation with proof of receipt" provides the originator of data with evidence that proves the data was received as addressed, and thus protects the originator against an attempt by the recipient to falsely deny receiving the data. 📬

(C) Phases of a Non-Repudiation Service: Ford [For94, For97] uses the term "critical action" to refer to the act of communication that is the subject of the service. Here's the lifecycle, bestie 🫶

--------   --------   --------   --------   --------   . --------
Phase 1:   Phase 2:   Phase 3:   Phase 4:   Phase 5:   . Phase 6:
Request    Generate   Transfer   Verify     Retain     . Resolve
Service    Evidence   Evidence   Evidence   Evidence   . Dispute
--------   --------   --------   --------   --------   . --------

Service    Critical   Evidence   Evidence   Archive    . Evidence
Request => Action  => Stored  => Is      => Evidence   . Is
Is Made    Occurs     For Later  Tested     In Case    . Verified
           and        Use |          ^      Critical   .     ^
           Evidence       v          |      Action Is  .     |
           Is         +-------------------+ Repudiated .     |
           Generated  |Verifiable Evidence|------> ... . ----+
                      +-------------------+

Phase / Explanation
-------------------
1. Before the critical action, the service requester asks, either
   implicitly or explicitly, to have evidence of the action be
   generated.
2. When the critical action occurs, evidence is generated by a
   process involving the potential repudiator and possibly also a
   trusted third party.
3. The evidence is transferred to the requester, or stored by a
   third party, for later use if needed.
4. The entity that holds the evidence tests to be sure that it
   will suffice if a dispute arises.
5. The evidence is retained for possible future retrieval and use.
6. In this phase, which occurs only if the critical action is
   repudiated, the evidence is retrieved from storage, presented,
   and verified to resolve the dispute.

no-PIN ORA (NORA) 🌙 (O) MISSI usage: An organizational RA that operates in a mode in which the ORA performs no card management functions and, therefore, does not require knowledge of either the SSO PIN or user PIN for an end user's FORTEZZA PC card.

NORA 💫 See: no-PIN ORA.

notarization 📜 (I) Registration of data under the authority or in the care of a trusted third party, thus making it possible to provide subsequent assurance of the accuracy of characteristics claimed for the data, such as content, origin, time, and delivery. [I7498 Part 2] (See: digital notary.)

NULL encryption algorithm 🫥 (I) An algorithm [R2410] that does nothing to transform plaintext data; i.e., a no-op. It originated because of IPsec ESP, which always specifies the use of an encryption algorithm to provide confidentiality. The NULL encryption algorithm is a convenient way to represent the option of not applying encryption in ESP (or in any other context where this is needed). 🍓

OAKLEY 🔑 (I) A key establishment protocol (proposed for IPsec but superseded by IKE) based on the Diffie-Hellman algorithm and designed to be a compatible component of ISAKMP. [R2412]

(C) OAKLEY establishes a shared key with an assigned identifier and associated authenticated identities for parties. I.e., OAKLEY provides authentication service to ensure the entities of each other's identity, even if the Diffie-Hellman exchange is threatened by active wiretapping. It also provides public-key forward secrecy for the shared key and supports key updates, incorporation of keys distributed by out-of-band mechanisms, and user-defined abstract group structures for use with Diffie-Hellman. 🌈

object 📦 (I) Trusted computer system modeling usage: A system element that contains or receives information. (See: Bell-LaPadula Model, trusted computer system.)

object identifier (OID) 🏷️ (I) An official, globally unique name for a thing, written as a sequence of integers (which are formed and assigned as defined in the ASN.1 standard) and used to reference the thing in abstract specifications and during negotiation of security services in a protocol.

(O) "A value (distinguishable from all other such values) which is associated with an object." [X680]

object identifier (continued)

okay so 🦋 objects named by OIDs are the leaves of the object identifier tree 🌳 (it's similar to the X.500 Directory Information Tree, but not the same, so don't mix them up 🙈). Every arc (aka every branch of the tree) gets labeled with a non-negative integer. An OID is just the sequence of integers on the path from the root down to the named object. Iconic, honestly 💅

The OID tree has three arcs right under the root: {0} for ITU-T, {1} for ISO, and {2} for both working together. Under ITU-T there are four arcs, and {0 0} is for ITU-T recommendations ✨ Under {0 0} there are 26 arcs, one for each series of recommendations starting with the letters A to Z, and under those are arcs for each individual recommendation. So the OID for ITU-T Recommendation X.509 is {0 0 24 509} 🎀 Under ISO there are four arcs, and {1 0 } is for ISO standards, with an arc for each ISO standard under it. That means the OID for ISO/IEC 9594-8 (the ISO number for X.509) is {1 0 9594 8} 🫶

the other examples are giving 🌸 ANSI registers organization names below the branch {joint-iso-ccitt(2) country(16) US(840) organization(1)}. The NIST CSOR records PKI objects below {joint-iso-ccitt(2) country(16) us(840) gov(101) csor(3) pki(4)}. The U.S. Department of Defense registers INFOSEC objects below {joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101) dod(2) infosec(1)}. And the OID for the PKIX private extension lives in an arc below the PKIX name space, as {iso(1) identified-organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7) 1 1} 🧚

object reuse 🧹

(N) Quoting the definition as written: "The reassignment and reuse of a storage medium (e.g., page frame, disk sector, magnetic tape) that once contained one or more [information] objects. To be securely reused and assigned to a new subject, storage media must contain no residual data (magnetic remanence) from the object(s) previously contained in the media." [NCS04] 💜

OCSP 💅 See: On-line Certificate Status Protocol.

octet

(I) A data unit of eight bits. (See: byte.) ✨

(c) Networking folks (especially in OSI standards) prefer "octet" over "byte", because some systems use "byte" for data storage units of a size other than eight 🤓

OFB 🦋 See: output feedback.

ohnosecond 💀

OID 🌸 See: object identifier.

On-line Certificate Status Protocol (OCSP)

(I) An Internet protocol that a client uses to get the validity status and other info about a digital certificate from a server. 🔥

(C) In some applications, like high-value commercial transactions, you might need certificate revocation status that's more timely than CRLs can give you, or other kinds of status info. OCSP can tell you the current revocation status of a digital certificate, either instead of or alongside checking a periodic CRL. An OCSP client sends a status request to an OCSP server and holds off on accepting the certificate in question until the server responds. ⏳

one-time pad

(I) An encryption algorithm where the key is a random sequence of symbols, and each symbol gets used for encryption only one time (to encrypt just one plaintext symbol and produce just one ciphertext symbol). A copy of the key gets used the same way for decryption 🔐

(C) To make sure it's really one-time, the copy used for encryption gets destroyed after use, and so does the copy used for decryption. This is the only encryption algorithm that's truly unbreakable, even with unlimited cryptanalysis resources [Schn] 👑 But key management costs and synchronization problems make it impractical except in special situations 😩

one-time password One-Time Password (OTP)

Not capitalized: a "one-time password" is a simple authentication technique where each password gets used only once, as authentication info that verifies an identity. This counters the replay attack threat that uses passwords captured by wiretapping 🙅‍♀️
Capitalized: "One-Time Password" is an Internet protocol [R1938] based on S/KEY. It uses a cryptographic hash function to generate one-time passwords for use as authentication info in system login and other processes that need protection against replay attacks 🌈

one-way encryption

(I) Irreversible transformation of plaintext to ciphertext, so the plaintext can't be recovered from the ciphertext by anything other than exhaustive procedures, even if the cryptographic key is known. (See: encryption.) 🧊

one-way function

(I) Quoting the definition as written: "A (mathematical) function, f, which is easy to compute, but which for a general value y in the range, it is computationally difficult to find a value x in the domain such that f(x) = y. There may be a few values of y for which finding x is not computationally difficult." [X509] 🧠

(D) ISDs SHOULD NOT use this term as a synonym for "cryptographic hash". 🙅‍♀️

open security environment

(O) U.S. Department of Defense usage: a system environment that meets at least one of the following conditions: (a) application developers (including maintainers) don't have sufficient clearance or authorization to give an acceptable presumption that they haven't introduced malicious logic; (b) configuration control doesn't give sufficient assurance that applications and the equipment are protected against the introduction of malicious logic before and during system application operation. [NCS04] (See: closed security environment.) 🔒

Open Systems Interconnection (OSI) Reference Model (OSIRM)

(N) A joint ISO/ITU-T standard [I7498 Part 1] for a seven-layer architectural communication framework for interconnecting computers in networks. 🏗️

(C) OSI-based standards include communication protocols that are mostly incompatible with the Internet Protocol Suite, but they also include security models, like X.509, that the Internet uses 🌐

(C) The OSIRM layers, from highest to lowest, are (7) Application, (6) Presentation, (5) Session, (4) Transport, (3) Network, (2) Data Link, and (1) Physical. In this Glossary, these layers are referred to by number so they don't get confused with Internet Protocol Suite layers, which get referred to by name 🔢

(C) Some unknown person described how the OSI layers match up with the seven deadly sins, and honestly it's unhinged in the best way 💀

7. Wrath: Application is always angry at the mess it sees below itself. (Hey! Who is it to be pointing fingers?) 😤
6. Sloth: Presentation is too lazy to do anything productive by itself. 🛋️
5. Lust: Session is always craving and demanding what truly belongs to Application's functionality. 😳
4. Avarice: Transport wants all of the end-to-end functionality. (Of course it deserves it, but life isn't fair.) 💸
3. Gluttony: (Connection-Oriented) Network is overweight and overbearing after trying too often to eat Transport's lunch. 🍔
2. Envy: Poor Data Link is always starved for attention. (With Asynchronous Transfer Mode, maybe it's feeling less neglected now.) 🥺
1. Pride: Physical has managed to avoid much of the controversy, and nearly all of the embarrassment, that the others have suffered. 😌

7. Doc: Application acts like it's in charge, but sometimes muddles its syntax. 👩‍⚕️
6. Sleepy: Presentation is indolent, guilty of the sin of Sloth. 😴
5. Dopey: Session is confused because its charter isn't very clear. 🥴
4. Grumpy: Transport is irritated because Network has encroached on Transport's turf. 😒
3. Happy: Network smiles for the same reason Transport is irritated. 😊
2. Sneezy: Data Link makes loud noises in the hope of attracting attention. 🤧
1. Bashful: Physical quietly does its work, unnoticed by the others. 🫣

operational integrity

(I) A synonym for "system integrity." It emphasizes the actual performance of system functions, not just the ability to perform them 💪

operations security (OPSEC)

(I) A process to identify, control, and protect evidence of the planning and execution of sensitive activities and operations, so potential adversaries can't learn about capabilities and intentions 🕵️‍♀️

OPSEC 🦋 See: operations security.

ORA 🌸 See: organizational registration authority.

Orange Book

(D) ISDs SHOULD NOT use this term as a synonym for "Trusted Computer System Evaluation Criteria" [CSC001, DOD1]. Instead, use the full, proper name of the document or, in later references, the abbreviation "TCSEC". (See: (usage note under) Green Book.) 📕

organizational certificate

(O) MISSI usage: a type of MISSI X.509 public-key certificate issued to support organizational message handling for the U.S. Government's Defense Message System. 🏛️

organizational registration authority (ORA)

(I) General usage: an RA for an organization. 🏢

(O) MISSI usage: the MISSI version of RA. It's a MISSI end entity that (a) helps a PCA, CA, or SCA register other end entities by gathering, verifying, and entering data and forwarding it to the signing authority, and (b) may also help with card management functions. An ORA is a local administrative authority. The term refers both to the office or role and to the person who fills it. An ORA does not sign certificates, CRLs, or CKLs. (See: no-PIN ORA, SSO-PIN ORA, user-PIN ORA.) 🪪

origin authentication origin authenticity

(D) ISDs SHOULD NOT use these terms, because they look like careless use of an internationally standardized term. Instead, use "data origin authentication" or "peer entity authentication," depending on which one is meant. 🙈

OSI 🌸 OSIRM 🌸 See: Open Systems Interconnection Reference Model.

OTP 🦋 See: One-Time Password.

out of band

(I) Transferring information over a channel that's outside (i.e., separate from) the channel normally used. (See: covert channel.) 📨

(C) Out-of-band mechanisms are often used to distribute shared secrets (e.g., a symmetric key) or other sensitive info items (e.g., a root key) that are needed to initialize or otherwise enable cryptography or other security mechanisms to work. (See: key distribution.) 🗝️

output feedback (OFB)

(N) A block cipher mode [FP081] that modifies electronic codebook mode to operate on plaintext segments of variable length, less than or equal to the block length. 🔁

(C) This mode works by directly using the algorithm's previously generated output block as the algorithm's next input block (i.e., "feeding back" the output block), and combining (exclusive OR-ing) the output block with the next plaintext segment (of block length or less) to form the next ciphertext segment. 🔄

outside attack outsider attack

See: (secondary definition under) attack. 🌟

P1363 See: IEEE P1363. 💅

PAA See: policy approving authority. 🎀

packet filter See: (secondary definition under) filtering router. 🦋

pagejacking (I) okay so this is short for "Web page hijacking" 😭 It's a masquerade attack where the attacker copies (steals) a home page or other material from the target server, rehosts the page on a server the attacker controls, and gets the rehosted page indexed by the major Web search services. The result is that browsers get diverted from the target server to the attacker's server. Not cute. 💀

(D) ISDs SHOULD NOT use this term without including a definition, because it isn't listed in most dictionaries and could confuse international readers. (See: (usage note under) Green Book.) 🌸

PAN See: primary account number. ✨

PAP See: Password Authentication Protocol. 🧚

partitioned security mode (N) This is a mode of operation for an information system where all users have the clearance, but not necessarily formal access authorization and need-to-know, for all information the system handles. It's defined in U.S. Department of Defense policy about system accreditation. [DoD2] 👑

passive attack See: (secondary definition under) attack. 🫶

passive wiretapping See: (secondary definition under) wiretapping. 🫶

password (I) A secret data value, usually a character string, that's used as authentication information. (See: challenge-response.) 🔐

(C) A password is usually matched with a user identifier that's explicitly presented in the authentication process, but in some cases the identity may be implicit. 🍓

(C) Using a password as authentication information assumes that only the system entity whose identity is being authenticated knows the password. So in a network environment where wiretapping is possible, simple authentication that relies on sending static (i.e., repeatedly used) passwords as cleartext is inadequate 🙈 (See: one-time password, strong authentication.)

Password Authentication Protocol (PAP) (I) A simple authentication mechanism in PPP. In PAP, a user identifier and password are transmitted in cleartext. [R1334] (See: CHAP.) 🦋

password sniffing (I) Passive wiretapping, usually on a local area network, to gain knowledge of passwords. (See: (usage note under) sniffing.) 👀

path discovery (I) For a digital certificate, this is the process of finding a set of public-key certificates that form a certification path from a trusted key to that specific certificate. 🌈

path validation (I) The process of validating (a) all of the digital certificates in a certification path and (b) the required relationships between those certificates, which then validates the contents of the last certificate on the path. (See: certificate validation.) ✅

payment card (N) SET usage: this collectively refers "to credit cards, debit cards, charge cards, and bank cards issued by a financial institution and which reflects a relationship between the cardholder and the financial institution." [SET2] 💳

payment gateway (O) SET usage: a system operated by an acquirer, or by a third party designated by an acquirer, to provide electronic commerce services to merchants in support of the acquirer. It interfaces with the acquirer to support the authorization, capture, and processing of merchant payment messages, including payment instructions from cardholders. [SET1, SET2] 🛒

payment gateway certification authority (SET PCA) (O) SET usage: a CA that issues digital certificates to payment gateways and is operated on behalf of a payment card brand, an acquirer, or another party according to brand rules. A SET PCA issues a CRL for compromised payment gateway certificates. [SET2] (See: PCA.) 👑

PC card (N) A type of credit card-sized, plug-in peripheral device that was originally developed to provide memory expansion for portable computers, but is also used for other kinds of functional expansion. (See: FORTEZZA, PCMCIA.) 💖

(C) The international PC Card Standard defines a non-proprietary form factor in three standard sizes--Types I, II and III--and each of them has a 68-pin interface between the card and the socket it plugs into. All three types have the same length and width, roughly the size of a credit card, but their thickness differs, from 3.3 to 10.5 mm. Examples include storage modules, modems, device interface adapters, and cryptographic modules. 🔥

PCA (D) ISDs SHOULD NOT use this acronym without a qualifying adjective, because that would be ambiguous. (See: Internet policy certification authority, (MISSI) policy creation authority, (SET) payment gateway certification authority.) 🙃

PCMCIA (N) Personal Computer Memory Card International Association, a group of manufacturers, developers, and vendors, founded in 1989 to standardize plug-in peripheral memory cards for personal computers. It's now extended to deal with any technology that works in the PC card form factor. (See: PC card.) 🎀

peer entity authentication (I) "The corroboration that a peer entity in an association is the one claimed." [I7498 Part 2] (See: authentication.) 🫶

peer entity authentication service (I) A security service that verifies an identity claimed by or for a system entity in an association. (See: authentication, authentication service.) 🛡️

(C) This service is used when an association is established, or at times during one, to confirm one entity's identity to another. That protects against a masquerade by the first entity. Unlike data origin authentication service, though, this service requires an association to exist between the two entities, and the corroboration it provides is valid only at the current time the service is provided. ⏰

PEM See: Privacy Enhanced Mail. 💌

penetration (I) Successful, repeatable, unauthorized access to a protected system resource. (See: attack, violation.) 🚨

penetration test (I) A system test, often part of system certification, in which evaluators try to circumvent the security features of the system. [NCS04] 🕵️‍♀️

(C) Penetration testing may be performed under various constraints and conditions. For a TCSEC evaluation, though, testers are assumed to have all system design and implementation documentation, including source code, manuals, and circuit diagrams, and to work under no greater constraints than those applied to ordinary users. 🧐

perfect forward secrecy See: (discussion under) public-key forward secrecy. 🔐

perimeter See: security perimeter. 🏰

periods processing (I) A mode of system operation in which information of different sensitivities is processed at distinctly different times by the same system, with the system properly purged or sanitized between periods. (See: color change.) 🧹

permission (I) A synonym for "authorization", but "authorization" is preferred in the PKI context. (See: privilege.) 🎟️

personal identification number (PIN) (I) A character string used as a password to gain access to a system resource. (See: authentication information.) 🔢

(C) Despite the words "identification" and "number", a PIN seldom serves as a user identifier, and a PIN's characters aren't necessarily all numeric. Honestly, a better name for this concept would have been "personal authentication system string (PASS)". 🙈

(C) Retail banking applications commonly use 4-digit PINs. FORTEZZA PC card's use up to 12 characters for user or SSO PINs. 💳

personality personality label (O) MISSI usage: a set of MISSI X.509 public-key certificates that have the same subject DN, together with their associated private keys and usage specifications, stored on a FORTEZZA PC card to support a role played by the card's user. 🎭

(C) When a card's user selects a personality to use in a FORTEZZA-aware application, the data determines the behavior traits (the personality) of the application. A card's user may have multiple personalities on the card. Each one has a "personality label", a user-friendly character string that applications can display to the user for selecting or changing the personality to be used. For example, a military user's card might contain three personalities: GENERAL HALFTRACK, COMMANDER FORT SWAMPY, and NEW YEAR'S EVE PARTY CHAIRMAN. 😭 Each personality includes one or more certificates of different types (such as DSA versus RSA), for different purposes (such as digital signature versus encryption), or with different authorizations. 🌟

personnel security (I) Procedures to make sure that persons who access a system have the proper clearance, authorization, and need-to-know that the system's security policy requires. 👥

PGP(trademark) See: Pretty Good Privacy. 💜

Photuris (I) A UDP-based key establishment protocol for session keys, designed for use with the IPsec protocols AH and ESP. It's been superseded by IKE. 🦋

phreaking (I) A contraction of "telephone breaking". It's an attack on or penetration of a telephone system or, by extension, any other communication or information system. [Raym] 📞

(D) ISDs SHOULD NOT use this term, because it isn't listed in most dictionaries and could confuse international readers. 🌸

physical security (I) Tangible means of preventing unauthorized physical access to a system. E.g., fences, walls, and other barriers; locks, safes, and vaults; dogs and armed guards; sensors and alarm bells. [FP031, R1455] 🔒

piggyback attack (I) A form of active wiretapping in which the attacker gains access to a system via intervals of inactivity in another user's legitimate communication connection. It's sometimes called a "between-the-lines" attack. (See: hijack attack, man-in-the-middle attack.) 🤫

PIN See: personal identification number. 🔢

ping of death (I) An attack that sends an improperly large ICMP [R0792] echo request packet (a "ping") with the intent of overflowing the input buffers of the destination machine and causing it to crash. 💀

ping sweep (I) An attack that sends ICMP [R0792] echo requests ("pings") to a range of IP addresses, with the goal of finding hosts that can be probed for vulnerabilities. 🔍

PKCS See: Public-Key Cryptography Standards. 🔑

PKCS #7 (N) A standard [PKC07, R2315] from the PKCS series. It defines a syntax for data that may have cryptography applied to it, such as digital signatures and digital envelopes. 📦

PKCS #10 (N) A standard [PKC10] from the PKCS series. It defines a syntax for requests for public-key certificates. (See: certification request.) 📝

(C) A PKCS #10 request contains a DN and a public key, may contain other attributes, and is signed by the entity making the request. The request is sent to a CA, who converts it to an X.509 public-key certificate (or some other form) and returns it, possibly in PKCS #7 format. 🥹

PKCS #11 🔐 (N) A standard [PKC11] from the PKCS series that defines a software CAPI called Cryptoki (pronounced "crypto-key"; short for "cryptographic token interface") for devices that hold cryptographic information and perform cryptographic functions. 💜

PKI 🧁 See: public-key infrastructure.

PKIX 🎀 (I) (1.) A contraction of "Public-Key Infrastructure (X.509)", the name of the IETF working group that is specifying an architecture and set of protocols needed to support an X.509-based PKI for the Internet. (2.) A collective name for that architecture and set of protocols. ✨

(C) okay so the goal of PKIX is to make X.509 public-key certificates easy to use across lots of Internet applications, and to make sure different implementations play nicely together 🫶 The resulting PKI is meant to be a framework that supports a range of trust and hierarchy environments and a range of usage environments, which is so flexible it's giving 💅 PKIX specifies (a) profiles of the v3 X.509 public-key certificate standards and the v2 X.509 CRL standards for the Internet; (b) operational protocols used by relying parties to obtain information such as certificates or certificate status; (c) management protocols used by system entities to exchange information needed for proper management of the PKI; and (d) information about certificate policies and CPSs, covering the areas of PKI security not directly addressed in the rest of PKIX. Main character energy, literally 👑

PKIX private extension 🌸 (I) PKIX defines a private extension to identify an on-line verification service supporting the issuing CA. 🦋

plaintext 🍓 (I) Data that is input to and transformed by an encryption process, or that is output by a decryption process. 🔥

(C) Usually, the plaintext input to an encryption operation is cleartext. But in some cases, the input is ciphertext that was output from another encryption operation. (See: superencryption.) 🙈

Point-to-Point Protocol (PPP) 🧚 (I) An Internet Standard protocol [R1661] for encapsulation and full-duplex transportation of network layer (mainly OSI layer 3) protocol data packets over a link between two peers, and for multiplexing different network layer protocols over the same link. Includes optional negotiation to select and use a peer entity authentication protocol to authenticate the peers to each other before they exchange network layer data. (See: CHAP, EAP, PAP.) ⭐

Point-to-Point Tunneling Protocol (PPTP) 💖 (I) An Internet client-server protocol (originally developed by Ascend and Microsoft) that enables a dial-up user to create a virtual extension of the dial-up link across a network by tunneling PPP over IP. (See: L2TP.) 🌈

(C) PPP can encapsulate any Internet Protocol Suite network layer protocol (or OSI layer 3 protocol). Therefore, PPTP does not specify security services; it depends on protocols above and below it to provide any needed security. PPTP makes it possible to divorce the location of the initial dial-up server (i.e., the PPTP Access Concentrator, the client, which runs on a special-purpose host) from the location at which the dial-up protocol (PPP) connection is terminated and access to the network is provided (i.e., the PPTP Network Server, which runs on a general-purpose host). Ngl that's a whole glow-up of a split 🫶

policy 🚫 (D) ISDs SHOULD NOT use this word as an abbreviation for either "security policy" or "certificate policy". Instead, to avoid misunderstanding, use the fully qualified term, at least at the point of first usage. 💅

policy approving authority (PAA) 👑 (O) MISSI usage: The top-level signing authority of a MISSI certification hierarchy. The term refers both to that authoritative office or role and to the person who plays that role. (See: root registry.) 🎀

(C) A PAA registers MISSI PCAs and signs their X.509 public-key certificates. A PAA issues CRLs but does not issue a CKL. A PAA may issue cross-certificates to other PAAs. 🧁

policy certification authority (Internet PCA) 🌸 (I) An X.509-compliant CA at the second level of the Internet certification hierarchy, under the Internet Policy Registration Authority (IPRA). Each PCA operates in accordance with its published security policy (see: certification practice statement) and within constraints established by the IPRA for all PCAs. [R1422]. (See: policy creation authority.) 🦋

policy creation authority (MISSI PCA) 🍓 (O) MISSI usage: The second level of a MISSI certification hierarchy; the administrative root of a security policy domain of MISSI users and other, subsidiary authorities. The term refers both to that authoritative office or role and to the person who fills that office. (See: policy certification authority.) ✨

(C) A MISSI PCA's certificate is issued by a policy approving authority. The PCA registers the CAs in its domain, defines their configurations, and issues their X.509 public-key certificates. (The PCA may also issue certificates for SCAs, ORAs, and other end entities, but a PCA does not usually do this.) The PCA periodically issues CRLs and CKLs for its domain. It's like a whole chain of command, iykyk 🫡

Policy Management Authority 🧚 (N) Canadian usage: An organization responsible for PKI oversight and policy management in the Government of Canada. 🍁

policy mapping 💜 (I) "Recognizing that, when a CA in one domain certifies a CA in another domain, a particular certificate policy in the second domain may be considered by the authority of the first domain to be equivalent (but not necessarily identical in all respects) to a particular certificate policy in the first domain." [X509] 🔥

POP3 📬 See: Post Office Protocol, version 3. 💌

POP3 APOP 🌈 (I) A POP3 "command" (better described as a transaction type, or a protocol-within-a-protocol) by which a POP3 client optionally uses a keyed hash (based on MD5) to authenticate itself to a POP3 server and, depending on the server implementation, to protect against replay attacks. (See: CRAM, POP3 AUTH, IMAP4 AUTHENTICATE.) 🙈

(C) The server includes a unique timestamp in its greeting to the client. The subsequent APOP command sent by the client to the server contains the client's name and the hash result of applying MD5 to a string formed from both the timestamp and a shared secret that is known only to the client and the server. APOP was designed to provide as an alternative to using POP3's USER and PASS (i.e., password) command pair, in which the client sends a cleartext password to the server. Cleartext passwords are giving "nope, not today" energy 😭

POP3 AUTH 🎀 (I) A "command" [R1734] (better described as a transaction type, or a protocol-within-a-protocol) in POP3, by which a POP3 client optionally proposes a mechanism to a POP3 server to authenticate the client to the server and provide other security services. (See: POP3 APOP, IMAP4 AUTHENTICATE.) 🧁

port scan 👀 (I) An attack that sends client requests to a range of server port addresses on a host, with the goal of finding an active port and exploiting a known vulnerability of that service. 💀

POSIX 🌸 (N) Portable Operating System Interface for Computer Environments, a standard [FP151, IS9945-1] (originally IEEE Standard P1003.1) that defines an operating system interface and environment to support application portability at the source code level. It is intended to be used by both application developers and system implementers. 💅

(C) P1003.1 supports security functionality like those on most UNIX systems, including discretionary access control and privilege. IEEE Draft Standard P1003.6.1 specifies additional functionality not provided in the base standard, including (a) discretionary access control, (b) audit trail mechanisms, (c) privilege mechanisms, (d) mandatory access control, and (e) information label mechanisms. 🦋

Post Office Protocol, version 3 (POP3) 💌 (I) An Internet Standard protocol [R1939] by which a client workstation can dynamically access a mailbox on a server host to retrieve mail messages that the server has received and is holding for the client. (See: IMAP4.) 📨

(C) POP3 has mechanisms for optionally authenticating a client to a server and providing other security services. (See: POP3 APOP, POP3 AUTH.) 🔐

PPP 🧚 See: Point-to-Point Protocol. 💖

PPTP 🧚 See: Point-to-Point Tunneling Protocol. 💖

pre-authorization ✨ (I) A capability of a CAW that enables certification requests to be automatically validated against data provided in advance to the CA by an authorizing entity. 🎀

Pretty Good Privacy(trademark) (PGP(trademark)) 🌈 (O) Trademarks of Network Associates, Inc., referring to a computer program (and related protocols) that uses cryptography to provide data security for electronic mail and other applications on the Internet. (See: MOSS, PEM, S/MIME.) 💜

(C) PGP encrypts messages with IDEA in CFB mode, distributes the IDEA keys by encrypting them with RSA, and creates digital signatures on messages with MD5 and RSA. To establish ownership of public keys, PGP depends on the web of trust. (See: Privacy Enhanced Mail.) 🔥

primary account number (PAN) 💳 (O) SET usage: "The assigned number that identifies the card issuer and cardholder. This account number is composed of an issuer identification number, an individual account number identification, and an accompanying check digit as defined by ISO 7812-1985." [SET2, IS7812] (See: bank identification number.) 🍓

(C) The PAN is embossed, encoded, or both on a magnetic-strip-based credit card. The PAN identifies the issuer to which a transaction is to be routed and the account to which it is to be applied unless specific instructions indicate otherwise. The authority that assigns the bank identification number part of the PAN is the American Bankers Association. 🌸

privacy 🫶 (I) The right of an entity (normally a person), acting in its own behalf, to determine the degree to which it will interact with its environment, including the degree to which the entity is willing to share information about itself with others. (See: anonymity.) 🙈

(O) "The right of individuals to control or influence what information related to them may be collected and stored and by whom and to whom that information may be disclosed." [I7498 Part 2] ✨

(D) ISDs SHOULD NOT use this term as a synonym for "data confidentiality" or "data confidentiality service", which are different concepts. Privacy is a reason for security rather than a kind of security. For example, a system that stores personal data needs to protect the data to prevent harm, embarrassment, inconvenience, or unfairness to any person about whom data is maintained, and to protect the person's privacy. For that reason, the system may need to provide data confidentiality service. 🔐💜

Privacy Enhanced Mail (PEM) 💌 (I) An Internet protocol to provide data confidentiality, data integrity, and data origin authentication for electronic mail. [R1421, R1422]. (See: MOSS, MSP, PGP, S/MIME.)

(C) Okay bestie, PEM encrypts messages with DES in CBC mode, does key distribution of DES keys by encrypting them with RSA, and signs messages with RSA over either MD2 or MD5. To prove who owns a public key, PEM uses a certification hierarchy with X.509 public-key certificates and X.509 CRLs that are signed with RSA and MD2. 🔐 (See: Pretty Good Privacy.)

(C) PEM is designed to work with a wide range of key management methods, but it's limited to specifying security services only for text messages. Like MOSS, it hasn't been widely implemented in the Internet. 🥲

private component 🎀 (I) A synonym for "private key".

(D) In most cases, ISDs SHOULD NOT use this term; to avoid confusing readers, use "private key" instead. However, the term MAY be used when specifically discussing a key pair; e.g., "A key pair has a public component and a private component."

private extension 🦋 See: (secondary definition under) extension.

private key 🔑 (I) The secret component of a pair of cryptographic keys used for asymmetric cryptography. (See: key pair, public key.)

(O) "(In a public key cryptosystem) that key of a user's key pair which is known only by that user." [X509]

privilege 👑 (I) An authorization or set of authorizations to perform security-relevant functions, especially in the context of a computer operating system.

privilege management infrastructure 🧱 (N) "The complete set of processes required to provide an authorization service", i.e., processes concerned with attribute certificates. [FPDAM] (See: PKI.)

(D) ISDs SHOULD NOT use this term and its definition because the definition is vague, and there is no consensus on an alternate definition. 🙈

privileged process ✨ (I) An computer process that is authorized (and, therefore, trusted) to perform some security-relevant functions that ordinary processes are not. (See: privilege, trusted process.)

procedural security 📋 (D) ISDs SHOULD NOT use this term as a synonym for "administrative security". Any type of security may involve procedures; therefore, the term may be misleading. Instead, use "administrative security", "communication security", "computer security", "emanations security", "personnel security", "physical security", or whatever specific type is meant. (See: security architecture.)

proprietary 🔒 (I) Refers to information (or other property) that is owned by an individual or organization and for which the use is restricted by that entity.

protected checksum 🛡️ (I) A checksum that is computed for a data object by means that protect against active attacks that would attempt to change the checksum to make it match changes made to the data object. (See: digital signature, keyed hash, (discussion under) checksum.

protected distribution system 🌸 (I) A wireline or fiber-optic system that includes sufficient safeguards (acoustic, electric, electromagnetic, and physical) to permit its use for unencrypted transmission of (cleartext) data.

protection authority 🧚 See: (secondary definition under) Internet Protocol Security Option.

protection ring 💍 (I) One of a hierarchy of privileged operation modes of a system that gives certain access rights to processes authorized to operate in that mode.

protocol 📜 (I) A set of rules (i.e., formats and procedures) to implement and control some type of association (e.g., communication) between systems. (E.g., see: Internet Protocol.)

(C) In particular, a series of ordered steps involving computing and communication that are performed by two or more system entities to achieve a joint objective. [A9042]

protocol suite 🧩 (I) A complementary collection of communication protocols used in a computer network. (See: Internet, OSI.)

proxy server 🪞 (I) A computer process--often used as, or as part of, a firewall--that relays a protocol between client and server computer systems, by appearing to the client to be the server and appearing to the server to be the client. (See: SOCKS.)

(C) In a firewall, a proxy server usually runs on a bastion host, which may support proxies for several protocols (e.g., FTP, HTTP, and TELNET). Instead of a client in the protected enclave connecting directly to an external server, the internal client connects to the proxy server which in turn connects to the external server. The proxy server waits for a request from inside the firewall, forwards the request to the remote server outside the firewall, gets the response, then sends the response back to the client. The proxy may be transparent to the clients, or they may need to connect first to the proxy server, and then use that association to also initiate a connection to the real server.

(C) Proxies are generally preferred over SOCKS for their ability to perform caching, high-level logging, and access control. A proxy can provide security service beyond that which is normally part of the relayed protocol, such as access control based on peer entity authentication of clients, or peer entity authentication of servers when clients do not have that capability. A proxy at OSI layer 7 can also provide finer-grained security service than can a filtering router at OSI layer 3. For example, an FTP proxy could permit transfers out of, but not into, a protected network. 💅

pseudo-random 🎲 (I) A sequence of values that appears to be random (i.e., unpredictable) but is actually generated by a deterministic algorithm. (See: random.)

pseudo-random number generator 🔢 (I) A process used to deterministically generate a series of numbers (usually integers) that appear to be random according to certain statistical tests, but actually are pseudo-random.

public component 🫧 (I) A synonym for "public key".

public key 🗝️ (I) The publicly-disclosable component of a pair of cryptographic keys used for asymmetric cryptography. (See: key pair, private key.)

(O) "(In a public key cryptosystem) that key of a user's key pair which is publicly known." [X509]

public-key certificate 📇 (I) A digital certificate that binds a system entity's identity to a public key value, and possibly to additional data items; a digitally-signed data structure that attests to the ownership of a public key. (See: X.509 public-key certificate.)

(C) The digital signature on a public-key certificate is unforgeable. Thus, the certificate can be published, such as by posting it in a directory, without the directory having to protect the certificate's data integrity.

(O) "The public key of a user, together with some other information, rendered unforgeable by encipherment with the private key of the certification authority which issued it." [X509]

public-key cryptography 🌈 (I) The popular synonym for "asymmetric cryptography".

Public-Key Cryptography Standards (PKCS) 📚 (I) A series of specifications published by RSA Laboratories for data structures and algorithm usage for basic applications of asymmetric cryptography. (See: PKCS #7, PKCS #10, PKCS #11.)

(C) The PKCS were begun in 1991 in cooperation with industry and academia, originally including Apple, Digital, Lotus, Microsoft, Northern Telecom, Sun, and MIT. Today, the specifications are widely used, but they are not sanctioned by an official standards organization, such as ANSI, ITU-T, or IETF. RSA Laboratories retains sole decision-making authority over the PKCS. 🏛️

public-key forward secrecy (PFS) 🦄 (I) For a key agreement protocol based on asymmetric cryptography, the property that ensures that a session key derived from a set of long-term public and private keys will not be compromised if one of the private keys is compromised in the future.

(C) Some existing RFCs use the term "perfect forward secrecy" but either do not define it or do not define it precisely. While preparing this Glossary, we tried to find a good definition for that term, but found this to be a muddled area. Experts did not agree. For all practical purposes, the literature defines "perfect forward secrecy" by stating the Diffie-Hellman algorithm. The term "public-key forward secrecy" (suggested by Hilarie Orman) and the "I" definition stated for it here were crafted to be compatible with current Internet documents, yet be narrow and leave room for improved terminology. 🤓

(C) Challenge to the Internet security community: We need a taxonomy--a family of mutually exclusive and collectively exhaustive terms and definitions to cover the basic properties discussed here--for the full range of cryptographic algorithms and protocols used in Internet Standards. 🫶

One concept of "forward secrecy" is that, given observations of the operation of a key establishment protocol up to time t, and given some of the session keys derived from those protocol runs, you cannot derive unknown past session keys or future session keys.
A related property is that, given observations of the protocol and knowledge of the derived session keys, you cannot derive one or more of the long-term private keys.
The "I" definition presented above involves a third concept of "forward secrecy" that refers to the effect of the compromise of long-term keys.
All three concepts involve the idea that a compromise of "this" encryption key is not supposed to compromise the "next" one. There also is the idea that compromise of a single key will compromise only the data protected by the single key. In Internet literature, the focus has been on protection against decryption of back traffic in the event of a compromise of secret key material held by one or both parties to a communication.

(C) Forward vs. backward: Experts are unhappy with the word "forward", because compromise of "this" encryption key also is not supposed to compromise the "previous" one, which is "backward" rather than forward. In S/KEY, if the key used at time t is compromised, then all keys used prior to that are compromised. If the "long-term" key (i.e., the base of the hashing scheme) is compromised, then all keys past and future are compromised; thus, you could say that S/KEY has neither forward nor backward secrecy. 💀

(C) Asymmetric vs. symmetric 🔐: Okay, so experts actually disagree about forward secrecy in symmetric crypto systems 🤔. Without asymmetric crypto, if any long-term key gets compromised, it seems like that can also compromise any session key derived from that long-term key 😭. Kerberos isn't forward secret, bestie 💀. If someone compromises a client's password (which compromises the key shared by the client and the authentication server), they also get the future session keys shared by the client and the ticket-granting server. Not it. 🙈

(C) Ordinary forward secrecy vs. "perfect" forward secret ✨: Experts are split on the difference between these two. Some say there's no difference at all. Some say the original naming was unfortunate and want to drop the word "perfect" entirely 💅. Others suggest using "forward secrecy" when one long-term private key is compromised, and adding "perfect" when both private keys are compromised (or, if the protocol is multi-party, all private keys) 🦋.

(C) Shoutout 📣: Bill Burr, Burt Kaliski, Steve Kent, Paul Van Oorschot, Michael Wiener, and especially Hilarie Orman all contributed ideas to this discussion 🫶💖.

$ public-key infrastructure (PKI)

(I) A PKI is a system of CAs (and, optionally, RAs and other supporting servers and agents) that handles a set of certificate management, archive management, key management, and token management functions for a community of users using asymmetric cryptography 🎀. (See: hierarchical PKI, mesh PKI, security management infrastructure, trust-file PKI.)

(O) PKIX usage: It's the whole package of hardware, software, people, policies, and procedures needed to create, manage, store, distribute, and revoke digital certificates based on asymmetric cryptography 🧚.

(C) The core PKI functions are (a) registering users and issuing their public-key certificates, (b) revoking certificates when required, and (c) archiving data needed to validate certificates at a much later time 📦. Key pairs for data confidentiality may be generated (and perhaps escrowed) by CAs or RAs. But requiring a PKI client to generate its own digital signature key pair helps keep the cryptographic system's integrity intact, because then only the client ever has the private key it uses 🔑. Also, an authority may be set up to approve or coordinate CPSs, which are the security policies that components of a PKI operate under 📜.

(C) A bunch of other servers and agents may support the core PKI, and PKI clients can get services from them 🌸. The full range of these services isn't fully understood yet and is still evolving. Supporting roles may include archive agent, certified delivery agent, confirmation agent, digital notary, directory, key escrow agent, key generation agent, naming agent (who makes sure issuers and subjects have unique identifiers within the PKI), repository, ticket-granting agent, and time stamp agent 🕰️.

$ RA

See: registration authority.

$ RA domains

(I) This is a capability of a CAW that lets a CA split up responsibility for certification requests among multiple RAs 🍓.

(C) It might be used to restrict access to private authorization data that comes with a certification request, and to spread out the job of reviewing and approving certification requests in high volume environments. RA domains might separate certification requests based on an attribute of the certificate subject, like an organizational unit 🗂️.

$ RADIUS

See: Remote Authentication Dial-In User Service.

$ Rainbow Series

(O) This is a set of more than 30 technical and policy documents with colored covers, issued by the NCSC. They go deep on the TCSEC and give guidance for meeting and applying the criteria 🌈. (See: Green Book, Orange Book, Red Book, Yellow Book.)

$ random

(I) General usage: In mathematics, "random" means "unpredictable" 🎲. A sequence of values is random if each value is obtained merely by chance and doesn't depend on the values before it. A selected individual value is random if every value in the total population of possibilities has an equal probability of being selected. [Knuth] (See: cryptographic key, pseudo-random, random number generator.)

(I) Security usage: In cryptography and other security applications, "random" means not only unpredictable, but also "unguessable" 🙀. When picking data values for cryptographic keys, "the requirement is for data that an adversary has a very low probability of guessing or determining." It's not enough to use data that "only meets traditional statistical tests for randomness or which is based on limited range sources, such as clocks. Frequently such random quantities are determinable [i.e., guessable] by an adversary searching through an embarrassingly small space of possibilities." [R1750]

$ random number generator

(I) A process used to generate an unpredictable, uniformly distributed series of numbers (usually integers) 🎰. (See: pseudo-random, random.)

(C) True random number generators are hardware-based devices that depend on the output of a "noisy diode" or other physical phenomena. [R1750] ⚡

$ RBAC

See: Role-Based Access Control.

$ RC2

$ RC4

See: Rivest Cipher #2, Rivest Cipher #4.

$ realm

(O) Kerberos usage: This is the domain of authority of a Kerberos server (made up of an authentication server and a ticket-granting server), including the Kerberized clients and the Kerberized application servers 👑

$ RED

(I) This is the designation for information system equipment or facilities that handle (and for data that contains) only plaintext (or, depending on the context, classified information), and for that data itself. The term comes from U.S. Government COMSEC terminology. (See: BLACK, RED/BLACK separation.) 🔴

$ Red Book

(D) ISDs SHOULD NOT use this term as a synonym for "Trusted Network Interpretation of the Trusted Computer System Evaluation Criteria" [NCS05] 🙅‍♀️. Instead, use the document's full proper name or, in later references, a more conventional abbreviation. (See: TCSEC, Rainbow Series, (usage note under) Green Book.)

$ RED/BLACK separation

(I) This is an architectural concept for cryptographic systems that strictly separates the parts of a system that handle plaintext (i.e., RED information) from the parts that handle ciphertext (i.e., BLACK information) 🖤❤️. The term comes from U.S. Government COMSEC terminology. (See: BLACK, RED.)

$ reference monitor

(I) "An access control concept that refers to an abstract machine that mediates all accesses to objects by subjects." [NCS04] (See: security kernel.) 🛡️

(C) A reference monitor should be (a) complete (i.e., it mediates every access), (b) isolated (i.e., it cannot be modified by other system entities), and (c) verifiable (i.e., small enough to be subjected to analysis and tests to ensure that it is correct) 💯.

$ reflection attack

(I) This is a type of replay attack where transmitted data gets sent back to its originator 🪞.

$ register

$ registration

(I) An administrative act or process where an entity's name and other attributes are established for the first time at a CA, before the CA issues a digital certificate that has the entity's name as the subject 📝. (See: registration authority.)

(C) Registration can be done either directly, by the CA, or indirectly, by a separate RA. The entity is presented to the CA or RA, and the authority either records the name(s) the entity claims or assigns the entity's name(s). The authority also determines and records other attributes of the entity that are to be bound in a certificate (such as a public key or authorizations), or kept in the authority's database (such as street address and telephone number) 🏠. The authority is responsible, possibly with help from an RA, for authenticating the entity's identity and verifying the correctness of the other attributes, in line with the CA's CPS.

How a claimed identity and other attributes are verified.
How organization affiliation or representation is verified.
What forms of names are permitted, such as X.500 DN, domain name, or IP address.
Whether names are required to be meaningful or unique, and within what domain.
How naming disputes are resolved, including the role of trademarks.
Whether certificates are issued to entities that are not persons.
Whether a person is required to appear before the CA or RA, or can instead be represented by an agent.
Whether and how an entity proves possession of the private key matching a public key.

$ registration authority (RA)

(I) An optional PKI entity (separate from the CAs) that doesn't sign digital certificates or CRLs. Instead, it's responsible for recording or verifying some or all of the information (especially the identities of subjects) that a CA needs to issue certificates and CRLs and to do other certificate management functions 🧾. (See: organizational registration authority, registration.)

(C) Sometimes a CA handles all certificate management functions for every end user it signs certificates for 🙌. Other times, like in a large or geographically dispersed community, it may be necessary or desirable to offload the secondary CA functions to an assistant, while the CA keeps the primary functions (signing certificates and CRLs). The tasks a CA can delegate to an RA may include personal authentication, name assignment, token distribution, revocation reporting, key generation, and archiving. An RA is an optional PKI component, separate from the CA, that takes on secondary functions. The duties given to RAs vary from case to case, but may include:

Verifying a subject's identity, i.e., performing personal authentication functions.
Assigning a name to a subject. (See: distinguished name.)
Verifying that a subject is entitled to have the attributes requested for a certificate.
Verifying that a subject possesses the private key that matches the public key requested for a certificate.
Performing functions beyond mere registration, such as generating key pairs, distributing tokens, and handling revocation reports. (Such functions may be assigned to a PKI element that is separate from both the CA and the RA.)

(I) PKIX usage: An optional PKI component, separate from the CA(s). The RA's functions vary from case to case, but may include identity authentication and name assignment, key generation and archiving of key pairs, token distribution, and revocation reporting. [R2510] 💜

(O) SET usage: "An independent third-party organization that processes payment card applications for multiple payment card brands and forwards applications to the appropriate financial institutions." [SET2] 💳✨

$ regrade 🌸 (I) Deliberately change the classification level of information in an authorized manner. 🫶

$ rekey 🔑 (I) Change the value of a cryptographic key that is being used in an application of a cryptographic system. (See: certificate rekey.) 💅

(C) For example, rekey is required at the end of a cryptoperiod or key lifetime. ⏰ okay so the key basically has a shelf life, and when it runs out you swap it. no cap, very responsible 🥹

$ reliability 🦋 (I) The ability of a system to perform a required function under stated conditions for a specified period of time. (See: availability, survivability.) 👑 this is giving "dependable and consistent" energy, iconic

$ relying party 💜 (N) A synonym for "certificate user". Used in a legal context to mean a recipient of a certificate who acts in reliance on that certificate. (See: ABA Guidelines.) ⚖️ it's the person who trusts the cert and then does something because of it, lowkey the main character of the whole PKI story 🎀

$ Remote Authentication Dial-In User Service (RADIUS) 🧚 (I) An Internet protocol [R2138] for carrying dial-in users' authentication information and configuration information between a shared, centralized authentication server (the RADIUS server) and a network access server (the RADIUS client) that needs to authenticate the users of its network access ports. (See: TACACS.) 📞🌈

(C) A user of the RADIUS client presents authentication information to the client, and the client passes that information to the RADIUS server. The server authenticates the client using a shared secret value, then checks the user's authentication information, and finally returns to the client all authorization and configuration information needed by the client to deliver service to the user. 🫠 so it's a whole chain of vibes: user → client → server → back to client with the goodies ✨

$ renew 🍓 See: certificate renewal.

$ replay attack 🙈 (I) An attack in which a valid data transmission is maliciously or fraudulently repeated, either by the originator or by an adversary who intercepts the data and retransmits it, possibly as part of a masquerade attack. (See: active wiretapping.) 😭 the audacity of copy-pasting someone's valid message and sending it again, not okay 💀

$ repository 📚 (I) A system for storing and distributing digital certificates and related information (including CRLs, CPSs, and certificate policies) to certificate users. (See: directory.) 💖

(O) "A trustworthy system for storing and retrieving certificates or other information relevant to certificates." [ABA]

(C) A certificate is published to those who might need it by putting it in a repository. The repository usually is a publicly accessible, on-line server. In the Federal Public-key Infrastructure, for example, the expected repository is a directory that uses LDAP, but also may be the X.500 Directory that uses DAP, or an HTTP server, or an FTP server that permits anonymous login. 🗂️ basically the group chat's shared drive, where everyone goes to grab the certs they need 🫶

$ repudiation 🙅‍♀️ (I) Denial by a system entity that was involved in an association (especially an association that transfers information) of having participated in the relationship. (See: accountability, non-repudiation service.) 🔥

(O) "Denial by one of the entities involved in a communication of having participated in all or part of the communication." [I7498 Part 2] 😌

$ Request for Comment (RFC) 📝 (I) One of the documents in the archival series that is the official channel for ISDs and other publications of the Internet Engineering Steering Group, the Internet Architecture Board, and the Internet community in general. [R2026, R2223] (See: Internet Standard.) 🌟

$ residual risk 🛡️ (I) The risk that remains after countermeasures have been applied. 🫧 even after you do all the protecting, a little bit of risk is still hanging around, sis

$ restore 🔄 See: card restore.

$ revocation 🚫 See: certificate revocation.

$ revocation date 🗓️ (N) In an X.509 CRL entry, a date-time field that states when the certificate revocation occurred, i.e., when the CA declared the digital certificate to be invalid. (See: invalidity date.) 💜

(C) The revocation date may not resolve some disputes because, in the worst case, all signatures made during the validity period of the certificate may have to be considered invalid. However, it may be desirable to treat a digital signature as valid even though the private key used to sign was compromised after the signing. If more is known about when the compromise actually occurred, a second date-time, an "invalidity date", can be included in an extension of the CRL entry. 🕰️ the drama of timelines, honestly so messy but so necessary 😩

$ revocation list 📜 See: certificate revocation list.

$ revoke ❌ See: certificate revocation.

$ RFC 🎀 See: Request for Comment.

$ risk ⚠️ (I) An expectation of loss expressed as the probability that a particular threat will exploit a particular vulnerability with a particular harmful result. 😬

(O) SET usage: "The possibility of loss because of one or more threats to information (not to be confused with financial or business risk)." [SET2]

$ risk analysis $ risk assessment 🔍 (I) A process that systematically identifies valuable system resources and threats to those resources, quantifies loss exposures (i.e., loss potential) based on estimated frequencies and costs of occurrence, and (optionally) recommends how to allocate resources to countermeasures so as to minimize total exposure. 🧐 it's basically the detective work before the security glow-up

(C) The analysis lists risks in order of cost and criticality, thereby determining where countermeasures should be applied first. It is usually financially and technically infeasible to counteract all aspects of risk, and so some residual risk will remain, even after all available countermeasures have been deployed. [FP031, R2196] 🥲 we can't block everything, periodt, so some risk always sticks around

$ risk management 🧹 (I) The process of identifying, controlling, and eliminating or minimizing uncertain events that may affect system resources. (See: risk analysis.) 💅 the ongoing cleanup crew of uncertain stuff

$ Rivest Cipher #2 (RC2) 🔐 (N) A proprietary, variable-key-length block cipher invented by Ron Rivest for RSA Data Security, Inc. (now a wholly-owned subsidiary of Security Dynamics, Inc.). 🏷️

$ Rivest Cipher #4 (RC4) 🔐 (N) A proprietary, variable-key-length stream cipher invented by Ron Rivest for RSA Data Security, Inc. (now a wholly-owned subsidiary of Security Dynamics, Inc.). 🌊

$ Rivest-Shamir-Adleman (RSA) 👑 (N) An algorithm for asymmetric cryptography, invented in 1977 by Ron Rivest, Adi Shamir, and Leonard Adleman [RSA78, Schn]. 🥂 the legends, all three of them 😭

(C) RSA uses exponentiation modulo the product of two large prime numbers. The difficulty of breaking RSA is believed to be equivalent to the difficulty of factoring integers that are the product of two large prime numbers of approximately equal size. 🧮 it's giving math but make it iconic

(C) To create an RSA key pair, randomly choose two large prime numbers, p and q, and compute the modulus, n = pq. Randomly choose a number e, the public exponent, that is less than n and relatively prime to (p-1)(q-1). Choose another number d, the private exponent, such that ed-1 evenly divides (p-1)(q-1). The public key is the set of numbers (n,e), and the private key is the set (n,d). 🗝️ okay this is the recipe part, read it slowly, it's a vibe

(C) It is assumed to be difficult to compute the private key (n,d) from the public key (n,e). However, if n can be factored into p and q, then the private key d can be computed easily. Thus, RSA security depends on the assumption that it is computationally difficult to factor a number that is the product of two large prime numbers. (Of course, p and q are treated as part of the private key, or else destroyed after computing n.) 🙈 the whole thing hinges on factoring being hard, so keep those primes locked up, bestie 🔒

(C) For encryption of a message, m, to be sent to Bob, Alice uses Bob's public key (n,e) to compute m**e (mod n) = c. She sends c to Bob. Bob computes c**d (mod n) = m. Only Bob knows d, so only Bob can compute c**d (mod n) = m to recover m. 💌 Alice sends the secret note, only Bob can open it, slay

(C) To provide data origin authentication of a message, m, to be sent to Bob, Alice computes m**d (mod n) = s, where (d,n) is Alice's private key. She sends m and s to Bob. To recover the message that only Alice could have sent, Bob computes s**e (mod n) = m, where (e,n) is Alice's public key. ✍️ signing it like a signature only she could make, iykyk

(C) To ensure data integrity in addition to data origin authentication requires extra computation steps in which Alice and Bob use a cryptographic hash function h (as explained for digital signature). Alice computes the hash value h(m) = v, and then encrypts v with her private key to get s. She sends m and s. Bob receives m' and s', either of which might have been changed from the m and s that Alice sent. To test this, he decrypts s' with Alice's public key to get v'. He then computes h(m') = v". If v' equals v", Bob is assured that m' is the same m that Alice sent. 🕵️‍♀️ hash it, sign the hash, and then Bob double-checks everything matches, no tampering allowed 🫶

$ role-based access control (RBAC) 🎭 (I) A form of identity-based access control where the system entities that are identified and controlled are functional positions in an organization or process. 💼 access by job title instead of by name, very organized energy ✨

$ root 🌳 (I) A CA that is directly trusted by an end entity. Acquiring the value of a root CA's public key involves an out-of-band procedure. 👑

(I) Hierarchical PKI usage: The CA that is the highest level (most trusted) CA in a certification hierarchy; i.e., the authority upon whose public key all certificate users base their trust. (See: top CA.)

(C) In a hierarchical PKI, a root issues public-key certificates to one or more additional CAs that form the second highest level. Each of these CAs may issue certificates to more CAs at the third highest level, and so on. To initialize operation of a hierarchical PKI, the root's initial public key is securely distributed to all certificate users in a way that does not depend on the PKI's certification relationships. The root's public key may be distributed simply as a numerical value, but typically is distributed in a self-signed certificate in which the root is the subject. The root's certificate is signed by the root itself because there is no higher authority in a certification hierarchy. The root's certificate is then the first certificate in every certification path. 🌲 the ultimate queen at the top, vouching for itself because nobody's above her 👑💖

(O) MISSI usage: A name previously used for a MISSI policy creation authority, which is not a root as defined above for general usage, but is a CA at the second level of the MISSI hierarchy, immediately subordinate to a MISSI policy approving authority. 🗃️

(O) UNIX usage: A user account (also called "superuser") that has all privileges (including all security-related privileges) and thus can manage the system and its other user accounts. 🐧 the all-powerful account, so please be careful with it 🙏

$ root certificate 📜 (I) A certificate for which the subject is a root. 🌟

(I) Hierarchical PKI usage: The self-signed public-key certificate at the top of a certification hierarchy. 🏔️

$ root key 🗝️ (I) A public key for which the matching private key is held by a root. 🔑

$ root registry 🏛️ (O) MISSI usage: A name previously used for a MISSI policy approving authority. 📎

$ router 🛣️ (I) A computer that is a gateway between two networks at OSI layer 3 and that relays and directs data packets through that internetwork. The most common form of router operates on IP packets. (See: bridge.) 🚦

(I) Internet usage: In the context of the Internet protocol suite, a networked computer that forwards Internet Protocol packets that are not addressed to the computer itself. (See: host.) 🦋 basically the friend who passes the note along to someone else, the best kind of middle-person 💕

RSA 🔐 See: Rivest-Shamir-Adleman. okay that's the whole entry, you know the drill 💅

rule-based security policy (I) A security policy built on global rules that apply to every user, no exceptions 🎀 These rules usually compare how sensitive the resource being accessed is against the attributes held by users, groups of users, or entities acting on behalf of users. [I7498 Part 2] (See: identity-based security policy.)

safety (I) The property of a system being free from risk of causing harm to system entities and to outside entities 🫶

SAID See: security association identifier.

salt 🧂 (I) A random value that gets concatenated with a password before the one-way encryption function is applied. This protects passwords stored in the database of an access control system. (See: initialization value.)

sanitize (I) Delete sensitive data from a file, a device, or a system. Or modify data so that its classification level can be downgraded 🧹

SASL See: Simple Authentication and Security Layer.

SCA See: subordinate certification authority.

scavenging See: (secondary definition under) threat consequence.

screening router (I) A synonym for "filtering router" 🚧

SDE See: Secure Data Exchange.

SDNS See: Secure Data Network System.

seal (O) To use cryptography to provide data integrity service for a data object. (See: sign, wrap.)

(D) ISDs SHOULD NOT use this definition. Instead, use wording that's more specific about the mechanism(s) used, such as "sign" when the mechanism is digital signature 🙈

secret 🤫 (I) (1.) Adjective: the condition of information being protected from being known by any system entities other than the ones who are meant to know it. (2.) Noun: an item of information that is protected that way.

secret-key cryptography (I) A synonym for "symmetric cryptography" 🗝️

Secure Data Exchange (SDE) (N) A local area network security protocol defined by the IEEE 802.10 standard 🌸

Secure Data Network System (SDNS) (N) An NSA program that developed security protocols for electronic mail (Message Security Protocol), OSI layer 3 (SP3), OSI layer 4 (SP4), and key management (KMP). Main character programme energy 👑

Secure Hash Standard (SHS) (N) The U.S. Government standard [FP180] that specifies the Secure Hash Algorithm (SHA-1). It's a cryptographic hash function that produces a 160-bit output (hash result) for input data of any length < 2**64 bits 🔥

Secure Hypertext Transfer Protocol (Secure-HTTP, S-HTTP) (I) An Internet protocol for providing client-server security services for HTTP communications. (See: https.) 🌐

(C) S-HTTP was originally specified by CommerceNet, a coalition of businesses that wanted to develop the Internet for commercial uses. Several message formats may be incorporated into S-HTTP clients and servers, particularly CMS and MOSS. S-HTTP supports a choice of security policies, key management mechanisms, and cryptographic algorithms, through option negotiation between parties for each transaction. It supports both asymmetric and symmetric key operation modes. S-HTTP tries not to presume a particular trust model, but it does try to facilitate multiply-rooted hierarchical trust, and it anticipates that principals may have many public key certificates. The way it plans ahead is so iconic ✨

Secure/MIME (S/MIME) (I) Secure/Multipurpose Internet Mail Extensions, an Internet protocol [R2633] that provides encryption and digital signatures for Internet mail messages 💌

Secure Sockets Layer (SSL) (N) An Internet protocol, originally developed by Netscape Communications, Inc., that uses connection-oriented end-to-end encryption. It provides data confidentiality service and data integrity service for traffic between a client (often a web browser) and a server, and it can optionally provide peer entity authentication between the client and the server. (See: Transport Layer Security.) 🔒

(C) SSL sits below HTTP and above a reliable transport protocol (TCP). SSL is independent of the application it encapsulates, so any higher-level protocol can layer on top of it transparently. However, many Internet applications might be better served by IPsec 🤷‍♀️

(C) SSL has two layers. (a) SSL's lower layer, the SSL Record Protocol, is layered on top of the transport protocol and encapsulates higher-level protocols. One such encapsulated protocol is the SSL Handshake Protocol. (b) SSL's upper layer provides asymmetric cryptography for server authentication (verifying the server's identity to the client) and optional client authentication (verifying the client's identity to the server). It also lets them negotiate a symmetric encryption algorithm and a secret session key (to use for data confidentiality) before the application protocol transmits or receives any data. A keyed hash provides data integrity service for the encapsulated data. Two layers, zero drama 🧚

secure state (I) A system condition in which no subject can access any object in an unauthorized manner. (See: (secondary definition under) Bell-LaPadula Model, clean system.) 🛡️

security (I) (1.) Measures taken to protect a system. (2.) The condition of a system that results from establishing and maintaining measures to protect the system. (3.) The condition of system resources being free from unauthorized access, and from unauthorized or accidental change, destruction, or loss. Main character energy 👑

security architecture (I) A plan and set of principles that describe (a) the security services a system is required to provide to meet the needs of its users, (b) the system elements required to implement those services, and (c) the performance levels required in those elements to deal with the threat environment. (See: (discussion under) security policy.) 🏗️

(C) A security architecture is the result of applying the system engineering process. A complete system security architecture includes administrative security, communication security, computer security, emanations security, personnel security, and physical security (e.g., see: [R2179]). A complete security architecture needs to deal with both intentional, intelligent threats and accidental kinds of threats. Both kinds, no skipping 🥹

security association (I) A relationship established between two or more entities so they can protect the data they exchange. The relationship is used to negotiate characteristics of protection mechanisms, but it does not include the mechanisms themselves. (See: association.) 🤝

(C) A security association describes how entities will use security services. The relationship is represented by a set of information that's shared between the entities, agreed upon, and considered a contract between them 📜

(O) IPsec usage: A simplex (uni-directional) logical connection created for security purposes and implemented with either AH or ESP (but not both). The security services a security association offers depend on the protocol selected, the IPsec mode (transport or tunnel), the endpoints, and the election of optional services within the protocol. A security association is identified by a triple consisting of (a) a destination IP address, (b) a protocol (AH or ESP) identifier, and (c) a Security Parameter Index 🦋

security association identifier (SAID) (I) A data field in a security protocol (such as NLSP or SDE) that identifies the security association a protocol data unit is bound to. The SAID value is usually used to select a key for decryption or authentication at the destination. (See: Security Parameter Index.) 🏷️

security audit (I) An independent review and examination of a system's records and activities. Its purpose is to determine the adequacy of system controls, ensure compliance with established security policy and procedures, detect breaches in security services, and recommend any changes that are indicated for countermeasures. [I7498 Part 2, NCS01] 🔍

(C) The basic audit objective is to establish accountability for system entities that initiate or participate in security-relevant events and actions. So, means are needed to generate and record a security audit trail, and to review and analyze that trail in order to discover and investigate attacks and security compromises. Receipts, babe 🧾

security audit trail (I) A chronological record of system activities that's detailed enough to reconstruct and examine the sequence of environments and activities surrounding or leading up to an operation, procedure, or event in a security-relevant transaction, from inception to final results. [NCS04] (See: security audit.) 🕰️

security class (D) A synonym for "security level". For consistency, ISDs SHOULD use "security level" instead of "security class" 📏

security clearance (I) A determination that a person is eligible, under the standards of a specific security policy, to be authorized to access sensitive information or other system resources. (See: clearance level.) 🪪

security compromise (I) A security violation in which a system resource is exposed, or is potentially exposed, to unauthorized access. (See: data compromise, violation.) 🚨

security domain See: domain.

security environment (I) The set of external entities, procedures, and conditions that affect the secure development, operation, and maintenance of a system 🌍

security event (I) An occurrence in a system that's relevant to the security of the system. (See: security incident.) 👀

(C) The term includes both events that are security incidents and events that are not. In a CA workstation, for example, a list of security events might include the following:

Performing a cryptographic operation, e.g., signing a digital certificate or CRL.
Performing a cryptographic card operation: creation, insertion, removal, or backup.
Performing a digital certificate lifecycle operation: rekey, renewal, revocation, or update.
Posting information to an X.500 Directory.
Receiving a key compromise notification.
Receiving an improper certification request.
Detecting an alarm condition reported by a cryptographic module.
Logging the operator in or out.
Failing a built-in hardware self-test or a software system integrity check.

security fault analysis (I) A security analysis, usually performed on hardware at a logic gate level (gate-by-gate), to determine the security properties of a device when a hardware fault is encountered. ⚡

security gateway (I) A gateway that separates trusted (or relatively more trusted) hosts on the internal network side from untrusted (or less trusted) hosts on the external network side. (See: firewall and guard.) 🌷

(O) IPsec usage: Okay, the official vibe from [R2401] is "An intermediate system that implements IPsec protocols." 🌐 Normally AH or ESP gets set up to serve a group of internal hosts, giving them security services whenever they talk to other external hosts or gateways that also implement IPsec. 🔐

$ security incident 🚨 (I) A security event that involves a security violation. (See: CERT, GRIP, security event, security intrusion, security violation.)

(C) Basically, it's a security-relevant system event where the system's security policy gets disobeyed or otherwise breached. 💅

(O) The definition in [R2350] is "Any adverse event which compromises some aspect of computer or network security." 🙈 (D) ISDs SHOULD NOT use this "O" definition, bestie, because (a) a security incident can happen without actually being harmful (i.e., adverse) and (b) this Glossary defines "compromise" more narrowly in relation to unauthorized access. 🫶

$ security intrusion 🕵️‍♀️ (I) A security event, or a combination of multiple security events, that makes up a security incident in which an intruder gains, or attempts to gain, access to a system (or system resource) without having authorization to do so. 😤

$ security kernel 🧱 (I) The definition from [NCS04] is "The hardware, firmware, and software elements of a trusted computing base that implement the reference monitor concept. It must mediate all accesses, be protected from modification, and be verifiable as correct." (See: reference monitor.) ✨

$ security label 🏷️ (I) A marking that is bound to a system resource and that names or designates the security-relevant attributes of that resource. [I7498 Part 2, R1457]

(C) The recommended definition is usefully broad, but people usually understand the term more narrowly, as a marking that represents the security level of an information object, i.e., a marking that shows how sensitive an information object is. [NCS04] 🎀

(C) System security mechanisms read security labels according to the applicable security policy to decide how to control access to the associated information, otherwise constrain its handling, and put appropriate security markings on visible (printed and displayed) images of it. [FP188] 👀

$ security level 📊 (I) The combination of a hierarchical classification level and a set of non-hierarchical category designations that represents how sensitive information is. (See: (usage note under) classification level, dominate, lattice model.) 💜

$ security management infrastructure (SMI) 🛠️ (I) System elements and activities that support security policy by monitoring and controlling security services and mechanisms, distributing security information, and reporting security events. The associated functions, per [I7498-4], are these: 🦋

Controlling (granting or restricting) access to system resources: this includes verifying authorizations and identities, controlling access to sensitive security data, and modifying access priorities and procedures when attacks happen.
Retrieving (gathering) and archiving (storing) security information: this includes logging security events and analyzing the log, monitoring and profiling usage, and reporting security violations. 📚
Managing and controlling the encryption process: this includes performing the functions of key management and reporting on key management problems. (See: public-key infrastructure.) 🔑

$ security mechanism ⚙️ (I) A process (or a device that incorporates such a process) that can be used in a system to implement a security service that is provided by or within the system. (See: (discussion under) security policy.) 🌸

(C) Some examples of security mechanisms are authentication exchange, checksum, digital signature, encryption, and traffic padding. 🧁

$ security model 🗺️ (I) A schematic description of a set of entities and relationships by which a specified set of security services is provided by or within a system. (See: (discussion under) security policy.) 🌈

$ security parameters index (SPI) 🔢 (I) IPsec usage: The type of security association identifier used in IPsec protocols. It's a 32-bit value used to tell apart different security associations that terminate at the same destination (IP address) and use the same IPsec security protocol (AH or ESP). It's carried in AH and ESP so the receiving system can figure out which security association to process a received packet under. 💖

$ security perimeter 🧱✨ (I) The boundary of the domain where a security policy or security architecture applies; i.e., the boundary of the space in which security services protect system resources. 🫧

$ security policy 📜 (I) A set of rules and practices that specify or regulate how a system or organization provides security services to protect sensitive and critical system resources. (See: identity-based security policy, rule-based security policy, security architecture, security mechanism, security model.) 👑

(O) According to [X509], it's "The set of rules laid down by the security authority governing the use and provision of security services and facilities." 🙌

(C) Ravi Sandhu notes that security policy is one of four layers of the security engineering process (as shown in the diagram below). Each layer gives a different view of security, ranging from what services are needed to how those services get implemented. 🧩

   What Security Services Should Be Provided?
    ^
    | + - - - - - - - - - - - +
    | | Security Policy       |
    | + - - - - - - - - - - - +    + - - - - - - - - - - - - - +
    | | Security Model        |    | A "top-level specification" |
    | + - - - - - - - - - - - + <- | is at a level below "model" |
    | | Security Architecture |    | but above "architecture".   |
    | + - - - - - - - - - - - +    + - - - - - - - - - - - - - +
    | | Security Mechanism    |
    | + - - - - - - - - - - - +
    v
   How Are Security Services Implemented?

$ Security Protocol 3 (SP3) 🦄 (O) A protocol [SDNS3] developed by SDNS to provide connectionless data security at the top of OSI layer 3. (See: NLSP.) 💫

$ Security Protocol 4 (SP4) 🧚 (O) A protocol [SDNS4] developed by SDNS to provide either connectionless or end-to-end connection-oriented data security at the bottom of OSI layer 4. (See: TLSP.) 🍓

$ security-relevant event 🔗 See: security event.

$ security service 🛡️ (I) A processing or communication service that a system provides to give a specific kind of protection to system resources. (See: access control service, audit service, availability service, data confidentiality service, data integrity service, data origin authentication service, non-repudiation service, peer entity authentication service, system integrity service.) 💅

(O) The definition in [I7498 Part 2] is "A service, provided by a layer of communicating open systems, which ensures adequate security of the systems or the data transfers." 🌷

$ security situation 🌡️ (I) ISAKMP usage: The set of all security-relevant information (e.g., network addresses, security classifications, manner of operation (normal or emergency)) that's needed to decide which security services are required to protect the association being negotiated. ✨

$ security token 🪙 See: token.

$ security violation 🚫 (I) An act or event that disobeys or otherwise breaches security policy. (See: compromise, penetration, security incident.) 😬

$ self-signed certificate 🪪 (I) A public-key certificate for which the public key bound by the certificate and the private key used to sign the certificate are components of the same key pair, and that pair belongs to the signer. (See: root certificate.) 🦋

$ semantic security 🔐 (I) An attribute of a encryption algorithm that formalizes the idea that the algorithm not only hides the plaintext but also reveals no partial information about it. Whatever is efficiently computable about the plaintext when given the ciphertext is also efficiently computable without the ciphertext. (See: indistinguishability.) 🧠💜

$ sensitive (information) 🥺 (I) Information is sensitive if disclosure, alteration, destruction, or loss of it would adversely affect the interests or business of its owner or user. (See: critical.) 🫶

$ separation of duties 👯‍♀️ (I) The practice of dividing the steps in a system function among different individuals, so that a single individual can't subvert the process. (See: dual control, administrative security.) 🎀

$ serial number 🔖 See: certificate serial number.

$ server 🖥️ (I) A system entity that provides a service in response to requests from other system entities called clients. 🌟

$ session key 🗝️ (I) In the context of symmetric encryption, a key that is temporary or is used for a relatively short period of time. (See: ephemeral key, key distribution center, master key.) ⏳

(C) Usually, a session key is used for a defined period of communication between two computers, such as for the duration of a single connection or transaction set. Or the key gets used in an application that protects relatively large amounts of data, so it needs to be rekeyed frequently. 🔄

$ SET 💳 See: SET Secure Electronic Transaction(trademark).

$ SET private extension 🧾 (O) One of the private extensions defined by SET for X.509 certificates. It carries information about hashed root key, certificate type, merchant data, cardholder certificate requirements, encryption support for tunneling, or message support for payment instructions. 🌸

$ SET qualifier 🎀 (O) A certificate policy qualifier that provides information about the location and content of a SET certificate policy.

(C) In addition to the policies and qualifiers it inherits from its own certificate, each CA in the SET certification hierarchy may add one qualifying statement to the root policy when it issues a certificate. That additional qualifier is a certificate policy for that CA. Each policy in a SET certificate may have these qualifiers: 💅

A URL where a copy of the policy statement may be found.
An electronic mail address where a copy of the policy statement may be found.
A hash result of the policy statement, computed using the indicated algorithm.
A statement declaring any disclaimers associated with the issuing of the certificate. 🫧

$ SET Secure Electronic Transaction(trademark) or SET(trademark) 💳✨ (N) okay bestie, SET is a protocol that MasterCard International and Visa International built together and then published as an open standard 🫶. Its whole job is keeping payment card transactions safe over unsecured networks like the Internet, so it covers confidentiality of transaction info, payment integrity, and authentication of the transaction participants 🔐. [SET1] (See: acquirer, brand, cardholder, dual signature, electronic commerce, issuer, merchant, payment gateway, third party.)

(C) This term and acronym are trademarks of SETCo 💅. MasterCard and Visa announced the SET standard on 1 February 1996. Then on 19 December 1997, they formed SET Secure Electronic Transaction LLC (commonly called "SETCo") to implement the SET 1.0 specification 🎀. A memorandum of understanding brings American Express and JCB Credit Card Company in as co-owners of SETCo, which is so iconic 👑.

$ SETCo 🌸 See: (secondary definition under) SET Secure Electronic Transaction.

$ SHA-1 🧚 See: Secure Hash Standard.

$ shared secret 🔑 (I) A synonym for "keying material" or "cryptographic key." Literally the same vibe 💜.

$ S-HTTP 🦋 See: Secure HTTP.

$ sign ✍️ (I) Create a digital signature for a data object.

$ signature 🌈 See: digital signature, electronic signature.

$ signature certificate 📜 (I) A public-key certificate that contains a public key meant for verifying digital signatures, NOT for encrypting data or doing other cryptographic functions 🙈.

(C) A v3 X.509 public-key certificate may have a keyUsage extension that shows what purpose the certified public key is intended for 💖.

$ signer ✍️🎀 (N) A human being or an organization entity that uses its private key to create a digital signature for a data object. [ABA]

$ SILS 🍓 See: Standards for Interoperable LAN/MAN Security.

$ simple authentication 🔓 (I) An authentication process that uses a password as the information needed to verify an identity claimed for an entity. (See: strong authentication.) Basically the basic option 😅.

(O) "Authentication by means of simple password arrangements." [X509]

$ Simple Authentication and Security Layer (SASL) 🔐✨ (I) An Internet specification [R2222] for adding authentication service to connection-based protocols. To use SASL, a protocol includes a command for authenticating a user to a server, and for optionally negotiating protection of later protocol interactions 💅. The command names a registered security mechanism. SASL mechanisms include Kerberos, GSSAPI, S/KEY, and others 👑. Some protocols that use SASL are IMAP4 and POP3.

$ Simple Key-management for Internet Protocols (SKIP) 🗝️ (I) A key distribution protocol that uses hybrid encryption to convey session keys, which are used to encrypt data in IP packets. [R2356] (See: IKE, IPsec.) Iconic energy 🦋.

(C) SKIP uses the Diffie-Hellman algorithm (or could use another key agreement algorithm) to generate a key-encrypting key for use between two entities 🫶. A session key is used with a symmetric algorithm to encrypt data in one or more IP packets that are sent from one entity to the other. The KEK is used with a symmetric algorithm to encrypt the session key, and the encrypted session key is placed in a SKIP header that gets added to each IP packet encrypted with that session key 🌸.

$ Simple Mail Transfer Protocol (SMTP) 📧 (I) A TCP-based, application-layer, Internet Standard protocol [R0821] for moving electronic mail messages from one computer to another. Classic 💌.

$ Simple Network Management Protocol (SNMP) 🖥️ (I) A UDP-based, application-layer, Internet Standard protocol [R2570, R2574] for conveying management information between managers and agents.

(C) SNMP version 1 uses cleartext passwords for authentication and access control. (See: community string.) Version 2 adds cryptographic mechanisms based on DES and MD5 🙈. Version 3 gets the glow-up 🌟: enhanced, integrated support for security services, including data confidentiality, data integrity, data origin authentication, and message timeliness and limited replay protection 💖.

$ simple security property 🛡️ See: (secondary definition under) Bell-LaPadula Model.

$ single sign-on 🎟️ (I) A system that lets a user access multiple computer platforms (usually a set of hosts on the same network) or application systems after being authenticated just one time. (See: Kerberos.) One login, all the access 💅✨.

(C) Typically, a user logs in just once and then gets transparently granted access to a variety of permitted resources, with no further login needed until they log out 🌈. Such a system is user friendly and lets authentication be managed consistently across an entire enterprise, but the downside is that all hosts and applications have to trust the same authentication mechanism 😭.

$ situation 🌸 See: security situation.

$ S/Key 🔢 (I) A security mechanism that uses a cryptographic hash function to generate a sequence of 64-bit, one-time passwords for remote user login. [R1760] Ur one-time passwords are giving main character energy 👑.

(C) The client generates a one-time password by applying the MD4 cryptographic hash function multiple times to the user's secret key. For each successive authentication of the user, the number of hash applications goes down by one. (Thus, an intruder using wiretapping cannot compute a valid password from knowledge of one previously used 🕵️‍♀️.) The server verifies a password by hashing the currently presented password (or initialization value) one time and comparing the hash result with the previously presented password 🫶.

$ SKIP 🗝️ See: Simple Key-management for IP.

$ SKIPJACK 🦋 (N) A Type II block cipher [NIST] with a block size of 64 bits and a key size of 80 bits. It was developed by NSA and formerly classified at the U.S. Department of Defense "Secret" level 🕶️. (See: CAPSTONE, CLIPPER, FORTEZZA, Key Exchange Algorithm.)

$ slot 🎴 (O) MISSI usage: One of the FORTEZZA PC card storage areas. Each one can hold an X.509 certificate and additional data associated with the certificate, such as the matching private key 🧩.

$ smart card 💳🧠 (I) A credit-card sized device with one or more integrated circuit chips, which perform the functions of a computer's central processor, memory, and input/output interface. (See: PC card.) Tiny brain, big energy ✨.

(C) Sometimes this term is used rather strictly to mean a card that closely matches the dimensions and appearance of the plastic credit cards that banks and merchants issue 💅. Other times it's used loosely to include cards that are bigger than credit cards, especially thicker ones, like PC cards.

(C) A "smart token" is a device that fits the smart card definition except that, instead of standard credit card dimensions, it's packaged in some other form, like a dog tag or door key shape 🔑🐶.

$ smart token 🪪 See: (secondary definition under) smart card.

$ SMI 🏢 See: security management infrastructure.

$ S/MIME 💌 See: Secure/MIME.

$ SMTP 📬 See: Simple Mail Transfer Protocol.

$ smurf 🫐 (I) Software that mounts a denial-of-service attack ("smurfing") by exploiting IP broadcast addressing and ICMP ping packets to cause flooding. (See: flood, ICMP flood.)

(D) > ISDs SHOULD NOT use this term, because it's not listed in most dictionaries and could confuse international readers 🌍.

(C) A smurf program builds a network packet that appears to come from another address, that of the "victim," which is either a host or an IP router 🙈. The packet holds an ICMP ping message addressed to an IP broadcast address, i.e., to all IP addresses in a given network. The echo responses to the ping message then return to the victim's address 😭. The goal of smurfing may be to deny service at a particular host or to flood all or part of an IP network.

$ sniffing 👃 (C) A synonym for "passive wiretapping." (See: password sniffing.)

(D) > ISDs SHOULD NOT use this term, because it unnecessarily duplicates the meaning of a term that's already better established. (See: (usage note under) Green Book. 📖

$ SNMP 🖥️ See: Simple Network Management Protocol.

$ social engineering 🎭 (I) A euphemism for non-technical or low-technology means, such as lies, impersonation, tricks, bribes, blackmail, and threats, used to attack information systems. (See: masquerade attack.) Lowkey scary 💀.

(D) > ISDs SHOULD NOT use this term, because it's vague. Instead, use a term that's specific about the means of attack 🎯.

$ SOCKS 🧦 (I) An Internet protocol [R1928] that provides a generalized proxy server, which lets client-server applications (like TELNET, FTP, and HTTP, running over either TCP or UDP) use the services of a firewall 🧱.

(C) SOCKS is layered under the application layer and above the transport layer 🌈. When a client inside a firewall wants to connect to an object that's reachable only through the firewall, it uses TCP to connect to the SOCKS server. Then it negotiates with the server for the authentication method to use, authenticates with the chosen method, and sends a relay request. The SOCKS server evaluates the request, typically based on source and destination addresses, and either establishes the appropriate connection or denies it 🚪.

$ soft TEMPEST 🧑‍💻 (O) The use of software techniques to reduce radio frequency information leakage from computer displays and keyboards. [Kuhn] (See: TEMPEST.) Software doing the most 💻✨.

$ software 💾 (I) Computer programs (which are stored in and executed by computer hardware) and associated data (which also is stored in the hardware), that may be dynamically written or modified during execution. (See: firmware, hardware.) 🌸

$ SORA 🗂️ See: SSO-PIN ORA.

$ source authentication 🙃 (D) > ISDs SHOULD NOT use this term, because it's ambiguous. If the intent is to authenticate the original creator or packager of data received, say "data origin authentication." If the intent is to authenticate the identity of the sender of data, say "peer entity authentication." (See: data origin authentication, peer entity authentication.) Be specific, babe 💅.

$ source integrity 🫶 (I) The degree of confidence that can be placed in information based on the trustworthiness of its sources. (See: integrity.)

$ SP3 🔐 See: Security Protocol 3.

$ SP4 🔐 See: Security Protocol 4.

$ spam 📨🚫 (I) (1.) Verb: To indiscriminately send unsolicited, unwanted, irrelevant, or inappropriate messages, especially commercial advertising in mass quantities. (2.) Noun: electronic "junk mail." [R2635] Ugh, the worst 😤.

(D) This term SHOULD NOT be written in upper-case letters, because SPAM(trademark) is a trademark of Hormel Foods Corporation. Hormel says, "We do not object to use of this slang term [spam] to describe [unsolicited commercial email (UCE)], although we do object to the use of our product image in association with that term. Also, if the term is to be used, it should be used in all lower-case letters to distinguish it from our trademark SPAM, which should be used with all uppercase letters." 🥫💅

(C) In sufficient volume, spam can cause denial of service. (See: flooding.) According to the SPAM Web site, the term was adopted because of the Monty Python skit where a group of Vikings sang a chorus of 'SPAM, SPAM, SPAM . . .' in an increasing crescendo, drowning out other conversation. So the analogy works: UCE was drowning out normal discourse on the Internet. 🎶🌊

SPC 🎀 See: software publisher certificate.

SPI 🦋 See: Security Parameters Index.

split key 🔑 (I) A cryptographic key that is divided into two or more separate data items that individually convey no knowledge of the whole key that results from combining the items. (See: dual control, split knowledge.)

split knowledge ✨ (I) A security technique in which two or more entities separately hold data items that individually convey no knowledge of the information that results from combining the items. (See: dual control, split key.)

(O) "A condition under which two or more entities separately have key components which individually convey no knowledge of the plaintext key which will be produced when the key components are combined in the cryptographic module." [FP140]

spoofing attack 🙈 (I) A synonym for "masquerade attack".

SSH 🔐 (I) A protocol for secure remote login and other secure network services over an insecure network.

Transport layer protocol: Provides server authentication, confidentiality, and integrity. It may optionally also provide compression. The transport layer will typically be run over a TCP/IP connection, but might also be used on top of any other reliable data stream.
User authentication protocol: Authenticates the client-side user to the server. It runs over the transport layer protocol.
Connection protocol: Multiplexes the encrypted tunnel into several logical channels. It runs over the user authentication protocol.

SSL 🧁 See: Secure Sockets Layer, Standard Security Label.

SSO 👑 See: system security officer.

SSO PIN 💜 (O) MISSI usage: One of two personal identification numbers that control access to the functions and stored data of a FORTEZZA PC card. Knowledge of the SSO PIN enables the card user to perform the FORTEZZA functions intended for use by an end user and also the functions intended for use by a MISSI certification authority. (See: user PIN.)

SSO-PIN ORA (SORA) 🌸 (O) MISSI usage: A MISSI organizational RA that operates in a mode in which the ORA performs all card management functions and, therefore, requires knowledge of the SSO PIN for an end user's FORTEZZA PC card.

Standards for Interoperable LAN/MAN Security (SILS) 🧩 (N) (1.) The IEEE 802.10 standards committee. (2.) A developing set of IEEE standards, which has eight parts: (a) Model, including security management, (b) Secure Data Exchange protocol, (c) Key Management, (d) [has been incorporated in (a)], (e) SDE Over Ethernet 2.0, (f) SDE Sublayer Management, (g) SDE Security Labels, and (h) SDE PICS Conformance. Parts b, e, f, g, and h are incorporated in IEEE Standard 802.10-1998.

star property ⭐ (I) (Written "*-property".) See: "confinement property" under Bell-LaPadula Model.

Star Trek attack 🚀 (C) An attack that penetrates your system where no attack has ever gone before. 🖖

steganography 🕵️‍♀️ (I) Methods of hiding the existence of a message or other data. This is different than cryptography, which hides the meaning of a message but does not hide the message itself. (See: cryptology.)

storage channel 📦 See: (secondary definition under) covert channel.

stream cipher 🌊 (I) An encryption algorithm that breaks plaintext into a stream of successive bits (or characters) and encrypts the n-th plaintext bit with the n-th element of a parallel key stream, thus converting the plaintext bit stream into a ciphertext bit stream. [Schn] (See: block cipher.)

strong authentication 💪 (I) An authentication process that uses cryptography--particularly public-key certificates--to verify the identity claimed for an entity. (See: X.509.)

(O) "Authentication by means of cryptographically derived credentials." [X509]

subject 🎭

(I) In a computer system: A system entity that causes information to flow among objects or changes the system state; technically, a process-domain pair. (See: Bell-LaPadula Model.)
(I) Of a certificate: The entity name that is bound to the data items in a digital certificate, and particularly a name that is bound to a key value in a public-key certificate.

subnetwork 🕸️ (N) An OSI term for a system of packet relays and connecting links that implement the lower three protocol layers of the OSIRM to provide a communication service that interconnects attached end systems. Usually the relays operate at OSI layer 3 and are all of the same type (e.g., all X.25 packet switches, or all interface units in an IEEE 802.3 LAN). (See: gateway, internet, router.)

subordinate certification authority (SCA) 🏛️ (I) A CA whose public-key certificate is issued by another (superior) CA. (See: certification hierarchy.)

(O) MISSI usage: The fourth-highest (bottom) level of a MISSI certification hierarchy; a MISSI CA whose public-key certificate is signed by a MISSI CA rather than by a MISSI PCA. A MISSI SCA is the administrative authority for a subunit of an organization, established when it is desirable to organizationally distribute or decentralize the CA service. The term refers both to that authoritative office or role, and to the person who fills that office. A MISSI SCA registers end users and issues their certificates and may also register ORAs, but may not register other CAs. An SCA periodically issues a CRL.

subordinate distinguished name 🧾 (I) An X.500 DN is subordinate to another X.500 DN if it begins with a set of attributes that is the same as the entire second DN except for the terminal attribute of the second DN (which is usually the name of a CA). For example, the DN <C=FooLand, O=Gov, OU=Treasurer, CN=DukePinchpenny> is subordinate to the DN <C=FooLand, O=Gov, CN=KingFooCA>.

superencryption 🔁 (I) An encryption operation for which the plaintext input to be transformed is the ciphertext output of a previous encryption operation.

survivability 🛡️ (I) The ability of a system to remain in operation or existence despite adverse conditions, including both natural occurrences, accidental actions, and attacks on the system. (See: availability, reliability.)

symmetric cryptography 🗝️ (I) A branch of cryptography involving algorithms that use the same key for two different steps of the algorithm (such as encryption and decryption, or signature creation and signature verification). (See: asymmetric cryptography.)

(C) Symmetric cryptography has been used for thousands of years [Kahn]. A modern example of a symmetric encryption algorithm is the U.S. Government's Data Encryption Algorithm. (See: DEA, DES.)

(C) Symmetric cryptography is sometimes called "secret-key cryptography" (versus public-key cryptography) because the entities that share the key, such as the originator and the recipient of a message, need to keep the key secret. For example, when Alice wants to ensure confidentiality for data she sends to Bob, she encrypts the data with a secret key, and Bob uses the same key to decrypt. Keeping the shared key secret entails both cost and risk when the key is distributed to both Alice and Bob. Thus, symmetric cryptography has a key management disadvantage compared to asymmetric cryptography. 🙄

symmetric key 🔐 (I) A cryptographic key that is used in a symmetric cryptographic algorithm.

SYN flood 🌧️ (I) A denial of service attack that sends a host more TCP SYN packets (request to synchronize sequence numbers, used when opening a connection) than the protocol implementation can handle. (See: flooding.)

system 💻 (C) In this Glossary, the term is mainly used as an abbreviation for "automated information system".

system entity 🤖 (I) An active element of a system--e.g., an automated process, a subsystem, a person or group of persons--that incorporates a specific set of capabilities.

system high ⬆️ (I) The highest security level supported by a system at a particular time or in a particular environment. (See: system high security mode.)

system high security mode 🔝 (I) A mode of operation of an information system, wherein all users having access to the system possess a security clearance or authorization, but not necessarily a need-to-know, for all data handled by the system. (See: mode of operation.)

(C) This mode is defined formally in U.S. Department of Defense policy regarding system accreditation [DOD2], but the term is widely used outside the Defense Department and outside the Government.

system integrity ✅ (I) "The quality that a system has when it can perform its intended function in a unimpaired manner, free from deliberate or inadvertent unauthorized manipulation." [NCS04] (See: system integrity service.)

system integrity service 🧱 (I) A security service that protects system resources in a verifiable manner against unauthorized or accidental change, loss, or destruction. (See: system integrity.)

system low ⬇️ (I) The lowest security level supported by a system at a particular time or in a particular environment. (See: system high.)

system resource 🎁 (I) Data contained in an information system; or a service provided by a system; or a system capability, such as processing power or communication bandwidth; or an item of system equipment (i.e., a system component--hardware, firmware, software, or documentation); or a facility that houses system operations and equipment.

system security officer (SSO) 🛎️ (I) A person responsible for enforcement or administration of the security policy that applies to the system.

system verification 🔍 See: (secondary definition under) verification.

TACACS 🏷️ TACACS+ 🏷️ See: Terminal Access Controller (TAC) Access Control System.

tamper 🔧 (I) Make an unauthorized modification in a system that alters the system's functioning in a way that degrades the security services that the system was intended to provide.

TCB 🧠 See: trusted computing base.

TCP 📡 See: Transmission Control Protocol.

TCP/IP 💖 (I) okay so this is just a synonym for "Internet Protocol Suite" 🎀 the big duo in it is TCP and IP, obviously ✨

TCSEC 🧚 See: Trusted Computer System Evaluation Criteria. (it's the same thing, just go look there bestie 💅)

TELNET 🌸 (I) a TCP-based, application-layer, Internet Standard protocol [R0854] for remote login from one host to another. it's giving old-school remote access and it's still iconic 👑

TEMPEST 🦋 (O) a nickname for specs and standards that limit how strong electromagnetic emanations are from electrical and electronic equipment, which lowers the risk of eavesdropping 👀 this term started in the U.S. Department of Defense. [Army, Kuhn, Russ] (See: emanation security, soft tempest.)

(D) ISDs SHOULD NOT use this term as a synonym for "electromagnetic emanations security" 🙈 not me using it wrong 😭

Terminal Access Controller (TAC) Access Control System (TACACS) 💜 (I) a UDP-based authentication and access control protocol [R1492] where a network access server gets an identifier and password from a remote terminal and passes them to a separate authentication server for verification 🔐

(C) TACACS was developed for ARPANET and has evolved for use in commercial equipment ✨ TACs were a type of network access server computer used to connect terminals to the early Internet, usually over dial-up modem connections 📞 TACACS used centralized authentication servers and served not only network access servers like TACs but also routers and other networked computing devices 🌈 TACs are no longer in use, but TACACS+ is. [R1983] main character glow-up 💅

"XTACACS": the name of Cisco Corporation's implementation, which enhances and extends the original TACACS. 🍓
"TACACS+": a TCP-based protocol that improves on TACACS and XTACACS by separating the functions of authentication, authorization, and accounting and by encrypting all traffic between the network access server and authentication server 🫶 it's extensible, so any authentication mechanism can be used with TACACS+ clients. literally so flexible 🔥

TESS 🎀 See: The Exponential Encryption System.

The Exponential Encryption System (TESS) 🔥 (I) a system of separate but cooperating cryptographic mechanisms and functions for the secure authenticated exchange of cryptographic keys, the generation of digital signatures, and the distribution of public keys 🔑 TESS uses asymmetric cryptography, based on discrete exponentiation, and a structure of self-certified public keys. [R1824] the math is so pretty ngl 🧚

threat ⭐ (I) a potential for violation of security, which exists when there is a circumstance, capability, action, or event that could breach security and cause harm 😬 (See: attack, threat action, threat consequence.)

(C) so basically, a threat is a possible danger that might exploit a vulnerability 💀 a threat can be either "intentional" (i.e., intelligent; e.g., an individual cracker or a criminal organization) or "accidental" (e.g., the possibility of a computer malfunctioning, or the possibility of an "act of God" such as an earthquake, a fire, or a tornado) 🌪️

(N) U. S. Government usage: the technical and operational capability of a hostile entity to detect, exploit, or subvert friendly information systems, plus the demonstrated, presumed, or inferred intent of that entity to conduct such activity. 🕵️‍♀️ very serious energy, bestie 😳

threat action 💥 (I) an assault on system security. (See: attack, threat, threat consequence.)

(C) a complete security architecture deals with both intentional acts (i.e. attacks) and accidental events [FIPS31] 🧠 various kinds of threat actions are defined as subentries under "threat consequence" 🫶

threat analysis 🔍 (I) an analysis of the probability of occurrences and consequences of damaging actions to a system. it's giving risk assessment vibes 📊

threat consequence 🌈 (I) a security violation that results from a threat action. includes disclosure, deception, disruption, and usurpation. (See: attack, threat, threat action.)

(C) the following subentries describe four kinds of threat consequences, and also list and describe the kinds of threat actions that cause each consequence 📋 threat actions that are accidental events are marked by * 🙈

1. "(Unauthorized) Disclosure" (a threat consequence): a circumstance or event whereby an entity gains access to data it is not authorized for. (See: data confidentiality.) the following threat actions can cause unauthorized disclosure: 🕳️
- A. "Exposure": a threat action whereby sensitive data is directly released to an unauthorized entity. this includes:
  - a. "Deliberate Exposure": intentional release of sensitive data to an unauthorized entity. 😤
  - b. "Scavenging": searching through data residue in a system to gain unauthorized knowledge of sensitive data. 🗑️
  - c* "Human error": human action or inaction that unintentionally results in an entity gaining unauthorized knowledge of sensitive data. 🥺
  - d* "Hardware/software error": system failure that results in an entity gaining unauthorized knowledge of sensitive data. 💻
- B. "Interception": a threat action whereby an unauthorized entity directly accesses sensitive data traveling between authorized sources and destinations. this includes: 📡
  - a. "Theft": gaining access to sensitive data by stealing a shipment of a physical medium, such as a magnetic tape or disk, that holds the data. 💼
  - b. "Wiretapping (passive)": monitoring and recording data that is flowing between two points in a communication system. (See: wiretapping.) 🎧
  - c. "Emanations analysis": gaining direct knowledge of communicated data by monitoring and resolving a signal that is emitted by a system and that contains the data but is not intended to communicate the data. (See: emanation.) 📶
- C. "Inference": a threat action whereby an unauthorized entity indirectly accesses sensitive data (but not necessarily the data contained in the communication) by reasoning from characteristics or byproducts of communications. this includes: 🧩
  - a. Traffic analysis: gaining knowledge of data by observing the characteristics of communications that carry the data. (See: (main Glossary entry for) traffic analysis.) 🚦
  - b. "Signals analysis": gaining indirect knowledge of communicated data by monitoring and analyzing a signal that is emitted by a system and that contains the data but is not intended to communicate the data. (See: emanation.) 📉
- D. "Intrusion": a threat action whereby an unauthorized entity gains access to sensitive data by circumventing a system's security protections. this includes: 🚨
  - a. "Trespass": gaining unauthorized physical access to sensitive data by circumventing a system's protections. 🚪
  - b. "Penetration": gaining unauthorized logical access to sensitive data by circumventing a system's protections. 🥷
  - c. "Reverse engineering": acquiring sensitive data by disassembling and analyzing the design of a system component. 🔧
  - d. Cryptanalysis: transforming encrypted data into plaintext without having prior knowledge of encryption parameters or processes. (See: (main Glossary entry for) cryptanalysis.) 🔓
2. "Deception" (a threat consequence): a circumstance or event that may result in an authorized entity receiving false data and believing it to be true. the following threat actions can cause deception: 🎭
- A. "Masquerade": a threat action whereby an unauthorized entity gains access to a system or performs a malicious act by posing as an authorized entity. (See: (main Glossary entry for) masquerade attack.) 🦹
  - a. "Spoof": attempt by an unauthorized entity to gain access to a system by posing as an authorized user. 👻
  - b. "Malicious logic": in context of masquerade, any hardware, firmware, or software (e.g., Trojan horse) that appears to perform a useful or desirable function, but actually gains unauthorized access to system resources or tricks a user into executing other malicious logic. (See: (main Glossary entry for) malicious logic.) 🐴
- B. "Falsification": a threat action whereby false data deceives an authorized entity. (See: active wiretapping.) 🙃
  - a. "Substitution": altering or replacing valid data with false data that serves to deceive an authorized entity. 🔄
  - b. "Insertion": introducing false data that serves to deceive an authorized entity. ➕
- C. "Repudiation": a threat action whereby an entity deceives another by falsely denying responsibility for an act. (See: non-repudiation service, (main Glossary entry for) repudiation.) 🙅‍♀️
  - a. "False denial of origin": action whereby the originator of data denies responsibility for its generation. 🫣
  - b. "False denial of receipt": action whereby the recipient of data denies receiving and possessing the data. 📭
3. "Disruption" (a threat consequence): a circumstance or event that interrupts or prevents the correct operation of system services and functions. (See: denial of service.) the following threat actions can cause disruption: ⚡
- A. "Incapacitation": a threat action that prevents or interrupts system operation by disabling a system component. 🛑
  - a. "Malicious logic": in context of incapacitation, any hardware, firmware, or software (e.g., logic bomb) intentionally introduced into a system to destroy system functions or resources. (See: (main Glossary entry for) malicious logic.) 💣
  - b. "Physical destruction": deliberate destruction of a system component to interrupt or prevent system operation. 🔨
  - c* "Human error": action or inaction that unintentionally disables a system component. 😵
  - d* "Hardware or software error": error that causes failure of a system component and leads to disruption of system operation. 🥀
  - e* "Natural disaster": any "act of God" (e.g., fire, flood, earthquake, lightning, or wind) that disables a system component. [FP031 section 2] 🌩️
- B. "Corruption": a threat action that undesirably alters system operation by adversely modifying system functions or data. 🌀
  - a. "Tamper": in context of corruption, deliberate alteration of a system's logic, data, or control information to interrupt or prevent correct operation of system functions. 🫠

That's the whole vibe for this part, bestie 🌈✨

b. "Malicious logic": Okay, in corruption land this is any hardware, firmware, or software (e.g., a computer virus) that someone intentionally introduces into a system to modify system functions or data. 💀 (See: (main Glossary entry for) malicious logic.)
c* "Human error": Human action or inaction that unintentionally results in the alteration of system functions or data. 🙈
d* "Hardware or software error": Error that results in the alteration of system functions or data. 🔧
e* "Natural disaster": Any "act of God" (e.g., power surge caused by lightning) that alters system functions or data. ⚡ [FP031 section 2]
C. "Obstruction": A threat action that interrupts delivery of system services by hindering system operations. 🚧
- a. "Interference": Disruption of system operations by blocking communications or user data or control information. 📵
- b. "Overload": Hindrance of system operation by placing excess burden on the performance capabilities of a system component. (See: flooding.) 🌊

"Usurpation" (a threat consequence): Main character energy alert 👑 This is when a circumstance or event results in control of system services or functions by an unauthorized entity. These threat actions can cause usurpation:
- A. "Misappropriation": A threat action whereby an entity assumes unauthorized logical or physical control of a system resource. 🫣
  - a. "Theft of service": Unauthorized use of service by an entity.
  - b. "Theft of functionality": Unauthorized acquisition of actual hardware, software, or firmware of a system component.
  - c. "Theft of data": Unauthorized acquisition and use of data.
- B. "Misuse": A threat action that causes a system component to perform a function or service that is detrimental to system security. 😤
  - a. "Tamper": In context of misuse, deliberate alteration of a system's logic, data, or control information to cause the system to perform unauthorized functions or services.
  - b. "Malicious logic": In context of misuse, any hardware, software, or firmware intentionally introduced into a system to perform or control execution of an unauthorized function or service. 🦠
  - c. "Violation of permissions": Action by an entity that exceeds the entity's system privileges by executing an unauthorized function. 🚫

thumbprint 🫆 (I) A pattern of curves formed by the ridges on the tip of a thumb. (See: biometric authentication, fingerprint.)

(D) ISDs SHOULD NOT use this term as a synonym for "hash result" because that meaning mixes concepts in a potentially misleading way. ⚠️

ticket 🎟️ (I) A synonym for "capability". (See: Kerberos.)

(C) A ticket is usually granted by a centralized access control server (ticket-granting agent) to authorize access to a system resource for a limited time. Tickets have been implemented with symmetric cryptography, but can also be implemented as attribute certificates using asymmetric cryptography. 🔐

timing channel ⏱️ See: (secondary definition under) covert channel.

TLS 🔒 See: Transport Layer Security. (See: TLSP.)

TLSP 🔒 See: Transport Layer Security Protocol. (See: TLS.)

token 🪙

(I) General usage: An object that is used to control access and is passed between cooperating entities in a protocol that synchronizes use of a shared resource. Usually, the entity that currently holds the token has exclusive access to the resource.
(I) Authentication usage: A data object or a portable, user-controlled, physical device used to verify an identity in an authentication process. (See: authentication information, dongle.)
(I) Cryptographic usage: See: cryptographic token.
(O) SET usage: "A portable device [e.g., smart card or PCMCIA card] specifically designed to store cryptographic information and possibly perform cryptographic functions in a secure manner." [SET2]

token backup 💾 (I) A token management operation that stores sufficient information in a database (e.g., in a CAW) to recreate or restore a security token (e.g., a smart card) if it is lost or damaged.

token copy 📋 (I) A token management operation that copies all the personality information from one security token to another. However, unlike in a token restore operation, the second token is initialized with its own, different local security values such as PINs and storage keys. 🧚

token management 🗂️ (I) The process of initializing security tokens (e.g., see: smart card), loading data into the tokens, and controlling the tokens during their life cycle. May include performing key management and certificate management functions; generating and installing PINs; loading user personality data; performing card backup, card copy, and card restore operations; and updating firmware. 💅

token restore ♻️ (I) A token management operation that loads a security token with data for the purpose of recreating (duplicating) the contents previously held by that or another token.

token storage key 🗝️ (I) A cryptography key used to protect data that is stored on a security token.

top CA 🏆 (I) A CA that is the highest level (i.e., is the most trusted CA) in a certification hierarchy. (See: root.)

top-level specification 📜 (I) "A non-procedural description of system behavior at the most abstract level; typically a functional specification that omits all implementation details." [NCS04] (See: (discussion under) security policy.)

"Descriptive top-level specification": One that is written in a natural language like English or an informal design notation. ✍️
"Formal top-level specification": One that is written in a formal mathematical language to enable theorems to be proven that show that the specification correctly implements a set of formal requirements or a formal security model. (See: correctness proof.) 🧮

traffic analysis 🕵️‍♀️ (I) Inference of information from observable characteristics of data flow(s), even when the data is encrypted or otherwise not directly available. Such characteristics include the identities and locations of the source(s) and destination(s), and the presence, amount, frequency, and duration of occurrence. (See: wiretapping.)

(O) "The inference of information from observation of traffic flows (presence, absence, amount, direction, and frequency)." [I7498 Part 2]

traffic flow confidentiality 🤫 (I) A data confidentiality service to protect against traffic analysis.

(O) "A confidentiality service to protect against traffic analysis." [I7498 Part 2]

traffic padding 🎈 (I) "The generation of spurious instances of communication, spurious data units, and/or spurious data within data units." [I7498 Part 2]

tranquillity property 🌙 See: (secondary definition under) Bell-LaPadula Model.

Transmission Control Protocol (TCP) 📦 (I) An Internet Standard protocol [R0793] that reliably delivers a sequence of datagrams (discrete sets of bits) from one computer to another in a computer network. (See: TCP/IP.)

(C) TCP is designed to fit into a layered hierarchy of protocols that support internetwork applications. TCP assumes it can obtain a simple, potentially unreliable datagram service (such as the Internet Protocol) from the lower-layer protocols. 🧱

Transport Layer Security (TLS) 🔐 (I) TLS Version 1.0 is an Internet protocol [R2246] based-on and very similar to SSL Version 3.0. (See: TLSP.)

Transport Layer Security Protocol (TLSP) 🛡️ (I) An end-to-end encryption protocol(ISO Standard 10736) that provides security services at the bottom of OSI layer 4, i.e., directly above layer 3. (See: TLS.)

transport mode vs. tunnel mode 🚇 (I) IPsec usage: Two ways to apply IPsec protocols (AH and ESP) to protect communications:

"Transport mode": The protection applies to (i.e., the IPsec protocol encapsulates) the packets of upper-layer protocols, the ones that are carried above IP.
"Tunnel mode": The protection applies to (i.e., the IPsec protocol encapsulates) IP packets.

(C) A transport mode security association is always between two hosts. In a tunnel mode security association, each end may be either a host or a gateway. Whenever either end of an IPsec security association is a security gateway, the association is required to be in tunnel mode. 🫶

trap door 🚪 (I) A hidden computer flaw known to an intruder, or a hidden computer mechanism (usually software) installed by an intruder, who can activate the trap door to gain access to the computer without being blocked by security services or mechanisms. (See: back door, Trojan horse.) 👀

triple DES 🧮 (I) A block cipher, based on DES, that transforms each 64-bit plaintext block by applying the Data Encryption Algorithm three successive times, using either two or three different keys, for an effective key length of 112 or 168 bits. [A9052] (See: DES.)

(C) IPsec usage: The algorithm variation proposed for ESP uses a 168-bit key, consisting of three independent 56-bit quantities used by the Data Encryption Algorithm, and a 64-bit initialization value. Each datagram contains an IV to ensure that each received datagram can be decrypted even when other datagrams are dropped or a sequence of datagrams is reordered in transit. [R1851] 🔁

triple-wrapped 🎁 (I) S/MIME usage: Data that has been signed with a digital signature, and then encrypted, and then signed again. [R2634]

Trojan horse 🐴 (I) A computer program that appears to have a useful function, but also has a hidden and potentially malicious function that evades security mechanisms, sometimes by exploiting legitimate authorizations of a system entity that invokes the program. 😱

trust 💜

(I) Information system usage: The extent to which someone who relies on a system can have confidence that the system meets its specifications, i.e., that the system does what it claims to do and does not perform unwanted functions. (See: trust level.)

(C) "trusted vs. trustworthy": In discussing a system or system process or object, this Glossary (and industry usage) prefers the term "trusted" to describe a system that operates as expected, according to design and policy. When the trust can also be guaranteed in some convincing way, such as through formal analysis or code review, the system is termed "trustworthy"; this differs from the ABA Guidelines definition (see: trustworthy system). ✨

(I) PKI usage: A relationship between a certificate user and a CA in which the user acts according to the assumption that the CA creates only valid digital certificates. 🫡

(O) Okay so the first bit is a quote from X.509 about "trust": generally, an entity can be said to 'trust' a second entity when it (the first entity) makes the assumption that the second entity will behave exactly as the first entity expects. This trust may apply only for some specific function. The key role of trust in [X.509] is to describe the relationship between an entity and a [certification] authority; an entity shall be certain that it can trust the certification authority to create only valid and reliable certificates. [X509] ✨

trust chain 🔗 (D) ISDs SHOULD NOT use this term as a synonym for "certification path" because it mixes concepts in a potentially misleading way. (See: trust.) 🙅‍♀️

trust-file PKI 📁 (I) A non-hierarchical PKI where each certificate user keeps a local file (used by application software) of public-key certificates they trust as starting points (aka roots) for certification paths. (See: hierarchical PKI, mesh PKI, root, web of trust.) 💖

(C) Popular browsers ship with an initial file of trusted certificates, which are often self-signed. Users can add certs to the file or delete from it. The user can manage it directly, or their organization can manage it from a centralized server. 🌸

trust hierarchy 🌳 (D) ISDs SHOULD NOT use this term as a synonym for "certification hierarchy" because it mixes concepts (see: trust) in a potentially misleading way, and it duplicates the meaning of another standardized term. (See: trust, web of trust.) 🙃

trust level 🎚️ (I) A characterization of a standard of security protection that a computer system has to meet. 🛡️

(C) The TCSEC defines eight trust levels, from lowest to highest: D, C1, C2, B1, B2, B3, and A1. A trust level isn't just about having security mechanisms. It also depends on using systems engineering discipline to properly structure the system, plus implementation analysis to make sure the system gives an appropriate degree of trust. Main character energy for real 👑

trusted 👀 See: (discussion under) trust.

trusted certificate 🏅 (I) A certificate a certificate user relies on as valid without needing validation testing. It's especially a public-key certificate used to provide the first public key in a certification path. (See: certification path, root certificate, validation.) 💯

(C) A trusted public-key certificate might be (a) the root certificate in a hierarchical PKI, (b) the certificate of the CA that issued the user's own certificate in a mesh PKI, or (c) any certificate the user accepted in a trust-file PKI. 🎀

trusted computer system 🖥️ (I) Multilevel security usage: "A system that employs sufficient hardware and software assurance measures to allow its use for simultaneous processing of a range of sensitive or classified information." [NCS04] (See: (discussion under) trust.) 🔐

Trusted Computer System Evaluation Criteria (TCSEC) 📘 (N) A standard for evaluating the security that operating systems provide [CSC001, DOD1]. It's informally called the "Orange Book" because of its cover color, and it's the first document in the Rainbow Series. 🌈 (See: Common Criteria, (usage note under) Green Book, Orange Book, trust level.)

trusted computing base (TCB) 🧱 (I) "The totality of protection mechanisms within a computer system, including hardware, firmware, and software, the combination of which is responsible for enforcing a security policy." [NCS04] (See: (discussion of "trusted" under) trust.) 🫶

trusted distribution 📦 (I) "A trusted method for distributing the TCB hardware, software, and firmware components, both originals and updates, that provides methods for protecting the TCB from modification during distribution and for detection of any changes to the TCB that may occur." [NCS04] 🚚

trusted key 🔑 (I) A public key a user relies on, especially one that can be used as the first public key in a certification path. (See: certification path, root key, validation.) ✨

(C) A trusted public key might be (a) the root key in a hierarchical PKI, (b) the key of the CA that issued the user's own certificate in a mesh PKI, or (c) any key the user accepted in a trust-file PKI. 💜

trusted path 🛤️ (I) COMPUSEC usage: a mechanism that lets a computer system user communicate directly and reliably with the trusted computing base (TCB). It can only be activated by the user or the TCB, and it can't be imitated by untrusted software within the computer. [NCS04] 🕵️‍♀️

(I) COMSEC usage: a mechanism that lets a person or process communicate directly with a cryptographic module. It can only be activated by the person, process, or module, and it can't be imitated by untrusted software within the module. [FP140] 🧚

trusted process 🛡️ (I) A system process with privileges that let it affect the state of system security. Through incorrect or malicious execution, it could therefore violate the system's security policy. (See: privileged process, (discussion of "trusted" under) trust.) 😬

trusted subnetwork 🕸️ (I) A subnetwork containing hosts and routers that trust each other not to engage in active or passive attacks. (There's also an assumption that the underlying communication channels, like telephone lines or a LAN, are protected from attack by some means.) 🍓

trusted system 🧾 See: (discussion under) trust, trusted computer system, trustworthy system.

Trusted Systems Interoperability Group (TSIG) 🤝 (N) A forum of computer vendors, system integrators, and users devoted to promoting interoperability of trusted computer systems. TSIG meetings are open to everyone working in the INFOSEC area. 🌷

trustworthy system 💅 (O) ABA usage: "Computer hardware, software, and procedures that: (a) are reasonably secure from intrusion and misuse; (b) provide a reasonably reliable level of availability, reliability, and correct operation; (c) are reasonably suited to performing their intended functions; and (d) adhere to generally accepted security principles." [ABA] This is somewhat different from other industry usage. (See: (discussion of "trusted vs. trustworthy" under) trust.) 🥹

TSIG 🔤 See: Trusted System Interoperability Group.

tunnel 🚇 (I) A communication channel created in a computer network by encapsulating (carrying, layering) a communication protocol's data packets in (on top of) a second protocol. That second protocol normally would be carried above, or at the same layer as, the first one. (See: L2TP, VPN.) 🫧

(C) Tunneling can involve almost any OSI or TCP/IP protocol layers. For example, a TCP connection between two hosts could conceivably be tunneled through email messages across the Internet. Most often, a tunnel is a logical point-to-point link (i.e., an OSI layer 2 connection) created by encapsulating the layer 2 protocol in a transport protocol (such as TCP), in a network or internetwork layer protocol (such as IP), or in another link layer protocol. Often, encapsulation is done with an extra, intermediate protocol, i.e., a tunneling protocol (such as L2TP), that is layered between the tunneled layer 2 protocol and the encapsulating protocol. 🎈

(C) Tunneling can move data between computers that use a protocol the connecting network doesn't support. Tunneling can also let one computer network use the services of a second network as though the second network were a set of point-to-point links between the first network's nodes. (See: virtual private network.) 🌊

(O) SET usage: the name of a SET private extension that indicates whether the CA or the payment gateway supports passing encrypted messages to the cardholder through the merchant. If it does, the extension lists OIDs of supported symmetric encryption algorithms. 💳

tunnel mode 🎭 (I) IPsec usage: See: transport mode vs. tunnel mode. 🙌

two-person control 👯‍♀️ (I) The close surveillance and control of a system, process, or materials (especially with regard to cryptography) at all times by a minimum of two appropriately authorized persons. Each one has to be capable of detecting incorrect and unauthorized procedures for the tasks being performed, and each one has to be familiar with established security requirements. (See: dual control, no-lone zone.) 🫂

Type I cryptography 🥇 (O) A cryptographic algorithm or device approved by NSA for protecting classified information. 🔒

Type II cryptography 🥈 (O) A cryptographic algorithm or device approved by NSA for protecting sensitive unclassified information (as specified in section 2315 of Title 10 United States Code, or section 3502(2) of Title 44, United States Code.) 🗂️

Type III cryptography 🥉 (O) A cryptographic algorithm or device approved as a Federal Information Processing Standard. 📜

UDP 📡 See: User Datagram Protocol. 💫

unclassified 🗒️ (I) Not classified. 🙂

unencrypted 🔓 (I) Not encrypted. 🌼

unforgeable ✍️ (I) Cryptographic usage: the property of a cryptographic data structure (a data structure defined using one or more cryptographic functions) that makes it computationally infeasible to construct (i.e., compute) an unauthorized but correct value of the structure without knowing one or more keys. (E.g., see: digital certificate.) 🧠

(C) This definition is narrower than general English usage, where "unforgeable" means unable to be fraudulently created or duplicated. In that broader sense, anyone can forge a digital certificate containing any set of data items whatsoever by generating the to-be-signed certificate and signing it with any private key whatsoever. But for PKI purposes, the forged data structure is invalid if it isn't signed with the true private key of the claimed issuer. So the forgery gets caught when a certificate user uses the claimed issuer's true public key to verify the signature. 🕵️

uniform resource identifier (URI) 🪪 (I) A type of formatted identifier that wraps up the name of an Internet object and labels it with an identification of its name space. That makes it a member of the universal set of names in registered name spaces, and an address referring to registered protocols or name spaces. [R1630] 🌍

(C) URIs are used in HTML to identify the target of hyperlinks. In common practice, URIs include uniform resource locators [R2368] and relative URLs, and they may be URNs. [R1808] 🔗

uniform resource locator (URL) 📍 (I) A type of formatted identifier that describes the access method and location of an information resource object on the Internet. [R1738] 🗺️

URL (C) okay so a URL is basically a URI that gives explicit instructions on how to access the named object 🦋 like, ftp://bbnarchive.bbn.com/foo/bar/picture/cambridge.zip is a URL, no cap. The part before the colon tells you the access scheme or protocol, and the part after the colon gets read according to that access method. Usually, two slashes after the colon mean the host name of a server, written as a domain name 🌸 In an FTP or HTTP URL, the host name is followed by the path name of a file on the server. The last part of a URL is optional, and it can be either a fragment identifier that points to a position in the file, or a query string ✨

uniform resource name (URN) (I) A URI with an institutional commitment to persistence and availability 🎀

untrusted process (I) A system process that can't affect the state of system security through incorrect or malicious operation, usually because its operation is confined by a security kernel. (See: trusted process.) 🔒

UORA See: user-PIN ORA.

update See: certificate update and key update.

URI See: uniform resource identifier.

URL See: uniform resource locator.

URN See: uniform resource name.

user (I) A person, organization entity, or automated process that accesses a system, whether authorized to do so or not. (See: [R2504].) 🙈

(C) Any ISD that uses this term SHOULD provide an explicit definition, because this term gets used in so many ways that it's super easy to misunderstand 💅

User Datagram Protocol (UDP) (I) An Internet Standard protocol [R0768] that provides a datagram mode of packet-switched computer communication in an internetwork. 🧚

(C) UDP is a transport layer protocol, and it assumes that IP is the underlying protocol. It lets application programs send transaction-oriented data to other programs with minimal protocol mechanism. UDP does not provide reliable delivery, flow control, sequencing, or the other end-to-end services that TCP provides. It's giving minimal, and that's the point 🌈

user identifier (I) A character string or symbol that a system uses to uniquely name a specific user or group of users. 🦋

user PIN (O) MISSI usage: One of two personal identification numbers that control access to the functions and stored data of a FORTEZZA PC card. Knowing the user PIN lets the card user perform the FORTEZZA functions that are meant for an end user. (See: SSO PIN.) 💜

user-PIN ORA (UORA) (O) A MISSI organizational RA that operates in a mode where the ORA performs only the subset of card management functions that are possible with knowledge of the user PIN for a FORTEZZA PC card. (See: no-PIN ORA, SSO-PIN ORA.) 🍓

usurpation See: (secondary definition under) threat consequence.

UTCTime (N) The ASN.1 data type "UTCTime" contains a calendar date (YYMMDD) and a time to a precision of either one minute (HHMM) or one second (HHMMSS). The time is either (a) Coordinated Universal Time or (b) the local time followed by an offset that lets Coordinated Universal Time be calculated. Note: UTCTime has the Year 2000 problem. 💀 (See: Coordinated Universal Time, GeneralizedTime.)

v1 certificate (C) This one is kinda messy 😭 It ambiguously refers to either an X.509 public-key certificate in its version 1 format, or an X.509 attribute certificate in its version 1 format. Lots of people who use this term don't realize that X.509 specifies attribute certificates that don't contain a public key. So ISDs MAY use this term as an abbreviation for "version 1 X.509 public-key certificate", but only after using the full term at the first instance.

(D) ISDs SHOULD NOT use this term as an abbreviation for "version 1 X.509 attribute certificate". Not it 🙅‍♀️

v1 CRL (I) An abbreviation for "X.509 CRL in version 1 format". ✨

(C) ISDs should use this abbreviation only after using the full term at its first occurrence and defining the abbreviation. Define it first, bestie 🎀

v2 certificate (I) An abbreviation for "X.509 public-key certificate in version 2 format". 🌸

(C) ISDs should use this abbreviation only after using the full term at its first occurrence and defining the abbreviation. Same energy as before 💅

v2 CRL (I) An abbreviation for "X.509 CRL in version 2 format". 🦋

(C) ISDs should use this abbreviation only after using the full term at its first occurrence and defining the abbreviation. Yes, again, you gotta spell it out first 🫶

v3 certificate (I) An abbreviation for "X.509 public-key certificate in version 3 format". 🧚

(C) ISDs should use this abbreviation only after using the full term at its first occurrence and defining the abbreviation. Literally the same rule, I'm not even kidding 😭

valid certificate (I) A digital certificate where the binding of the data items can be trusted, meaning one that can be validated successfully. 🔐 (See: validate vs. verify.)

valid signature (D) ISDs SHOULD NOT use this term. Instead, say "authentic signature" 🙈 This Glossary recommends saying "validate the certificate" and "verify the signature", so calling a signature "valid" would be inconsistent. (See: validate vs. verify.)

validate vs. verify (C) The PKI community is kinda all over the place with these words when describing what a certificate user does to make sure a digital certificate can be trusted 🤷‍♀️ Usually we say "verify the signature" but "validate the certificate". Basically we "verify" atomic truths but "validate" data structures, relationships, and systems that are made of or depend on verified items. But honestly, too often verify and validate get used interchangeably, and that's messy 😩

ISDs SHOULD comply with the following two rules to keep things consistent and to line Internet security terminology up with ordinary English 💖

Rule 1: Use "validate" when referring to a process intended to establish the soundness or correctness of a construct. (E.g., see: certificate validation.) ✨
Rule 2: Use "verify" when referring to a process intended to test or prove the truth or accuracy of a fact or value. (E.g., see: authenticate.) 🔍

The reason for Rule 1 is that "valid" comes from a word that means "strong" in Latin. So to validate means making sure a construction is sound. A certificate user validates a public-key certificate to establish trust in the binding that the certificate asserts between an identity and a key. (To validate can also mean to officially approve something. For example, NIST validates cryptographic modules for conformance with FIPS PUB 140-1. 🏛️)

The reason for Rule 2 is that "verify" comes from a word that means "true" in Latin. So to verify means proving the truth of an assertion by examining evidence or performing tests. To verify an identity, an authentication process examines identification information that is presented or generated. To validate a certificate, a certificate user verifies the digital signature on the certificate by performing calculations, verifies that the current time is within the certificate's validity period, and may need to validate a certification path involving additional certificates. Lots of steps, but it's giving thorough 🌟

validation See: validate vs. verify.

validity period (I) A data item in a digital certificate that specifies the time period for which the binding between data items is valid. This is especially the binding between the subject name and the public key value in a public-key certificate. It's valid except if the certificate appears on a CRL or the key appears on a CKL. ⏰

value-added network (VAN) (I) A computer network or subnetwork (which is usually a commercial enterprise) that transmits, receives, and stores EDI transactions on behalf of its customers. 📦

(C) A VAN may also provide extra services, ranging from EDI format translation, to EDI-to-FAX conversion, to fully integrated business systems. 💼

VAN See: value-added network.

verification

System verification: The process of comparing two levels of system specification for proper correspondence, such as comparing a security policy with a top-level specification, a top-level specification with source code, or source code with object code. [NCS04] 🔬
Identification verification: Presenting information to establish the truth of a claimed identity. 🪪

verify See: validate vs. verify.

violation See: security violation.

virtual private network (VPN) (I) A restricted-use, logical (i.e., artificial or simulated) computer network that is built from the system resources of a relatively public, physical (i.e., real) network, such as the Internet. It's often created by using encryption (located at hosts or gateways), and often by tunneling links of the virtual network across the real network. 🦋

(C) For example, say a corporation has LANs at several different sites, each connected to the Internet by a firewall. The corporation could create a VPN by (a) using encrypted tunnels to connect from firewall to firewall across the Internet and (b) not allowing any other traffic through the firewalls. A VPN is generally less expensive to build and operate than a dedicated real network, because the virtual network shares the cost of system resources with other users of the real network. Main character energy, but make it budget-friendly 💸

virus (I) A hidden, self-replicating section of computer software, usually malicious logic, that propagates by infecting (i.e., inserting a copy of itself into and becoming part of) another program. A virus can't run by itself. Its host program has to be run to make the virus active 🦠

VPN See: virtual private network.

vulnerability (I) A flaw or weakness in a system's design, implementation, or operation and management that could be exploited to violate the system's security policy. 🚨

(C) Most systems have vulnerabilities of some sort, but that doesn't mean they're too flawed to use. Not every threat results in an attack, and not every attack succeeds. Success depends on the degree of vulnerability, the strength of attacks, and how well any countermeasures in use actually work. If the attacks needed to exploit a vulnerability are super hard to carry out, the vulnerability may be tolerable. If the perceived benefit to an attacker is small, even an easily exploited vulnerability may be tolerable. But if the attacks are well understood and easily made, and the vulnerable system is used by a wide range of users, then it's likely there will be enough benefit for someone to make an attack. Scary but true 😳

W3 See: World Wide Web.

war dialer (I) A computer program that automatically dials a series of telephone numbers to find lines connected to computer systems. It catalogs those numbers so a cracker can try to break into the systems. 📞💀

Wassenaar Arrangement 🌍

(N) okay so the Wassenaar Arrangement on Export Controls for Conventional Arms and Dual-Use Goods and Technologies is this global, multilateral agreement that 33 countries approved in July 1996. The whole point is regional and international security and stability, by promoting information exchange and greater responsibility in transfers of arms and dual-use items, so we don't end up with destabilizing accumulations. 🫶 (See: International Traffic in Arms Regulations.)

(C) The Arrangement started operating in September 1996 💅 The participating countries are Argentina, Australia, Austria, Belgium, Bulgaria, Canada, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Japan, Luxembourg, Netherlands, New Zealand, Norway, Poland, Portugal, Republic of Korea, Romania, Russian Federation, Slovak Republic, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom, and United States. They meet regularly in Vienna, which is where the Arrangement has its headquarters 🌸

Participating countries use their national policies to make sure transfers don't contribute to building or boosting military capabilities that undermine the goals of the arrangement, and that items aren't diverted to support those capabilities. They keep effective export controls on the items on the agreed lists, and those lists get reviewed periodically to account for tech developments and experience gained 🔥 Through transparency and exchanging views and info, suppliers can build common understandings of the risks tied to transfers and figure out how far they can coordinate national control policies to combat those risks. Members send semi-annual notifications of arms transfers, covering seven categories derived from the UN Register of Conventional Arms. They also report transfers, or denials of transfers, of certain controlled dual-use items. BUT (no caps, just vibes) the decision to transfer or deny any item is the sole responsibility of each participating country. Everything done under the arrangement follows national legislation and policies and is carried out at national discretion 🦋

watermarking 💧

See: digital watermarking.

web of trust 🔐

(O) PGP usage: a trust-file PKI technique used in PGP to build a file of validated public keys. You make personal judgments about whether you can trust certain people to be holding properly certified keys of other people 🧚 (See: certification hierarchy, mesh PKI.)

web server 🕸️

(I) A software process that runs on a host computer connected to the Internet and responds to HTTP requests for documents from client web browsers ✨

web vs. Web 🕸️💕

(I) Capitalized: ISDs SHOULD capitalize "Web" when using the term, as either a noun or an adjective, to refer specifically to the World Wide Web. (Similarly, see: internet vs. Internet.)
(C) Not capitalized: ISDs SHOULD NOT capitalize "web" when using the term, usually as an adjective, to refer generically to technology like web browsers, web servers, HTTP, and HTML, that gets used in the Web or similar networks 🎀

(C) IETF documents SHOULD spell out "World Wide Web" fully at the first instance of usage, and SHOULD Use "Web" and "web" especially carefully where confusion with the PGP "web of trust" is possible 🙈

wiretapping 🎣

(I) An attack that intercepts and accesses data and other information contained in a flow in a communication system 👀

(C) Okay, history moment: the term originally meant making a mechanical connection to an electrical conductor linking two nodes. It's now used for reading information from any sort of medium used for a link, or even directly from a node, like a gateway or subnetwork switch 📼

(C) "Active wiretapping" tries to alter the data or otherwise affect the flow. "Passive wiretapping" only tries to observe the flow and gain knowledge of the info it contains 🦋 (See: active attack, end-to-end encryption, passive attack.)

work factor 💪

(I) General security usage: the estimated amount of effort or time a potential intruder can be expected to spend penetrating a system, or defeating a particular countermeasure, when using specified amounts of expertise and resources 🕵️‍♀️

(I) Cryptography usage: the estimated amount of computing time and power needed to break a cryptographic system 🔢

World Wide Web ("the Web", WWW, W3) 🌐

(N) The global, hypermedia-based collection of information and services that lives on Internet servers and gets accessed by browsers using Hypertext Transfer Protocol and other information retrieval mechanisms 💖 (See: web vs. Web, [R2084].)

worm 🐛

(I) A computer program that can run independently, propagate a complete working version of itself onto other hosts on a network, and may consume computer resources destructively. Iconic for all the wrong reasons 💀 (See: Morris Worm, virus.)

wrap 🎁

(O) To use cryptography to provide data confidentiality service for a data object. (See: encrypt, seal.)

(D) ISDs SHOULD NOT use this term with this definition, because it duplicates the meaning of other, standard terms. Instead, use "encrypt", or use a term that's specific about the mechanism used 🙅‍♀️

WWW 🌏

See: World Wide Web.

X.400 📨

(N) An ITU-T Recommendation [X400] that is one part of a joint ITU-T/ISO multi-part standard (X.400-X.421) defining the Message Handling Systems. (The ISO equivalent is IS 10021, parts 1-7.) (See: Message Handling Systems.)

X.500 / X.500 Directory 🗂️

(N) An ITU-T Recommendation [X500] that is one part of a joint ITU-T/ISO multi-part standard (X.500-X.525) defining the X.500 Directory. That's a conceptual collection of systems providing distributed directory capabilities for OSI entities, processes, applications, and services. (The ISO equivalent is IS 9594-1 and related standards, IS 9594-x.) (See: directory vs. Directory, X.509.)

(C) The X.500 Directory is structured as a tree, called the Directory Information Tree, and info is stored in directory entries. Each entry is a collection of information about one object, and each object has a DN. A directory entry is made up of attributes, each with a type and one or more values. For example, if a PKI uses the Directory to distribute certificates, the X.509 public-key certificate of an end user is normally stored as a value of an attribute of type "userCertificate" in the Directory entry whose DN is the subject of the certificate 🌳

X.509 🔏

(N) An ITU-T Recommendation [X509] defining a framework to provide and support data origin authentication and peer entity authentication services. It includes formats for X.509 public-key certificates, X.509 attribute certificates, and X.509 CRLs. (The ISO equivalent is IS 9498-4.) (See: X.500.)

(C) X.509 describes two levels of authentication: simple authentication based on a password, and strong authentication based on a public-key certificate 🔑

X.509 attribute certificate 🧾

(N) An attribute certificate in the version 1 (v1) format defined by X.509. (The v1 designation for an X.509 attribute certificate is disjoint from the v1 designation for an X.509 public-key certificate, and from the v1 designation for an X.509 CRL.)

(C) An X.509 attribute certificate has a subject field, but it's a separate data structure from that subject's public-key certificate. A subject can have multiple attribute certificates associated with each of its public-key certificates, and an attribute certificate may be issued by a different CA than the one that issued the associated public-key certificate 🫠

(C) An X.509 attribute certificate contains a sequence of data items and has a digital signature computed from that sequence. Besides the signature, it contains items 1 through 9 listed below:

1. version                Identifies v1.
2. subject                Is one of the following:
   2a. baseCertificateID   - Issuer and serial number of an
                             X.509 public-key certificate.
   2b. subjectName         - DN of the subject.
3. issuer                 DN of the issuer (the CA who signed).
4. signature              OID of algorithm that signed the cert.

5. serialNumber           Certificate serial number;
                          an integer assigned by the issuer.
6. attCertValidityPeriod  Validity period; a pair of UTCTime
                          values: "not before" and "not after".
7. attributes             Sequence of attributes describing the
                          subject.
8. issuerUniqueId         Optional, when a DN is not sufficient.
9. extensions             Optional.

X.509 authority revocation list 📜

(N) An ARL in one of the formats defined by X.509, either version 1 (v1) or version 2 (v2). It's a specialized kind of certificate revocation list 🚫

X.509 certificate 📇

(N) Either an X.509 public-key certificate or an X.509 attribute certificate.

(C) This Glossary uses the term with the precise meaning recommended here. But some people who use the term may not realize that X.509 specifies attribute certificates that don't contain a public key. Even among those who do know, the term is commonly used as shorthand for "X.509 public-key certificate". ISDs MAY use the term as an abbreviation for "X.509 public-key certificate", but only after using the full term at the first instance 💅

(D) ISDs SHOULD NOT use this term as an abbreviation to mean "X.509 attribute certificate" 🙃

X.509 certificate revocation list (CRL) 🗒️

(N) A CRL in one of the formats defined by X.509, either version 1 (v1) or version 2 (v2). (The v1 and v2 designations for an X.509 CRL are disjoint from the v1 and v2 designations for an X.509 public-key certificate, and from the v1 designation for an X.509 attribute certificate.) (See: certificate revocation.)

(C) ISDs SHOULD NOT refer to an X.509 CRL as a digital certificate. Still, an X.509 CRL does meet this Glossary's definition of "digital certificate" 🤓 Like a digital certificate, an X.509 CRL makes an assertion and is signed by a CA. But instead of binding a key or other attributes to a subject, an X.509 CRL asserts that certain previously-issued X.509 certificates have been revoked ⭐

(C) An X.509 CRL contains a sequence of data items and has a digital signature computed on that sequence. Besides the signature, both v1 and v2 contain items 2 through 6b listed below. Version 2 contains item 1 and may optionally contain 6c and 7. 🌈

      1. version                Optional. If present, identifies v2.
      2. signature              OID of the algorithm that signed CRL.
      3. issuer                 DN of the issuer (the CA who signed).
      4. thisUpdate             A UTCTime value.
      5. nextUpdate             A UTCTime value.
      6. revokedCertificates    3-tuples of 6a, 6b, and (optional) 6c:
         6a. userCertificate    A certificate's serial number.
         6b. revocationDate     UTCTime value for the revocation date.
         6c. crlEntryExtensions Optional.
      7. crlExtensions          Optional.

$ X.509 public-key certificate 🎀

(N) Okay so this is an X.509 public-key certificate, and it can be in one of the formats defined by X.509: version 1 (v1), version 2 (v2), or version 3 (v3). 💅 The v1 and v2 labels here are totally separate from the v1 and v2 labels for an X.509 CRL, and from the v1 label for an X.509 attribute certificate, so don't mix them up, bestie! 🙈

(C) An X.509 public-key certificate is a sequence of data items with a digital signature computed over that sequence. 🔐 Every version has the signature plus items 1 through 7 below. Only v2 and v3 certificates may also have items 8 and 9, and only v3 may have item 10. ✨

      1. version                 Identifies v1, v2, or v3.
      2. serialNumber            Certificate serial number;
                                 an integer assigned by the issuer.
      3. signature               OID of algorithm that was used to
                                 sign the certificate.
      4. issuer                  DN of the issuer (the CA who signed).
      5. validity                Validity period; a pair of UTCTime
                                 values: "not before" and "not after".
      6. subject                 DN of entity who owns the public key.
      7. subjectPublicKeyInfo    Public key value and algorithm OID.
      8. issuerUniqueIdentifier  Defined for v2, v3; optional.
      9. subjectUniqueIdentifier Defined for v2, v2; optional.
      10. extensions             Defined only for v3; optional.

$ XTACACS 🧚

Just see: (secondary definition under) Terminal Access Controller (TAC) Access Control System. 👑

$ Yellow Book 📘

(D) Ngl, this one's a big no-no: ISDs SHOULD NOT use this term as a synonym for "Computer Security Requirements: Guidance for Applying the Department of Defense Trusted Computer System Evaluation Criteria in Specific Environments" [CSC3]. 🙅‍♀️ Instead, use the full proper name of the document or, in later references, a conventional abbreviation. (See: (usage note under) Green Book, Rainbow Series.) 🌈

$ zeroize 🧽

(I) Use erasure or other means to render stored data unusable and unrecoverable, particularly a key stored in a cryptographic module or other device. 🔥

(O) Erase electronically stored data by altering the contents of the data storage so as to prevent the recovery of the data. [FP140] 💀

4. References ✨

Okay so this Glossary is all about the Internet Standards Process 🌐, which means the reading list leans heavily on international, governmental, and industry standards docs, with only a few other texts thrown in. 📚 RFCs are listed, but Internet-Drafts are not, because they aren't an archival document series and shouldn't be cited or quoted in an RFC. 🫶

   [A3092]  American National Standards Institute, "American National
            Standard Data Encryption Algorithm", ANSI X3.92-1981, 30 Dec
            1980.

   [A9009]  ---, "Financial Institution Message Authentication
            (Wholesale)", ANSI X9.9-1986, 15 Aug 1986.

   [A9017]  ---, "Financial Institution Key Management (Wholesale)",
            X9.17, 4 Apr 1985. [Defines procedures for the manual and
            automated management of keying material and uses DES to
            provide key management for a variety of operational
            environments.]

   [A9042]  ---, "Public key Cryptography for the Financial Service
            Industry: Agreement of Symmetric Keys Using Diffie-Hellman
            and MQV Algorithms", X9.42, 29 Jan 1999.

   [A9052]  ---, "Triple Data Encryption Algorithm Modes of Operation",
            X9.52-1998, ANSI approval 9 Nov 1998.

   [A9062]  ---, "Public Key Cryptography for the Financial Services
            Industry: The Elliptic Curve Digital Signature Algorithm
            (ECDSA)", X9.62-1998, ANSI approval 7 Jan 1999.

   [ABA]    American Bar Association, "Digital Signature Guidelines:
            Legal Infrastructure for Certification Authorities and
            Secure Electronic Commerce", Chicago, IL, 1 Aug 1996.

   [ACM]    Association for Computing Machinery, "Communications of the
            ACM", Jul 1998 issue with: Minerva M. Yeung, "Digital
            Watermarking"; Nasir Memom and Ping Wah Wong, "Protecting
            Digital Media Content"; and Scott Craver, Boon-Lock Yeo, and
            Minerva Yeung, "Technical Trials and Legal Tribulations".

   [Army]   U.S. Army Corps of Engineers, "Electromagnetic Pulse (EMP)
            and Tempest Protection for Facilities", EP 1110-3-2, 31 Dec
            1990.

   [B7799]  British Standards Institution, "Information Security
            Management, Part 1: Code of Practice for Information
            Security Management", BS 7799-1:1999, effective 15 May 1999.

            ---, ---, "Part 2: Specification for Information Security
            Management Systems", BS 7799-2:1999, effective 15 May 1999.

   [Bell]   D. E. Bell and L. J. LaPadula, "Secure Computer Systems:
            Mathematical Foundations and Model", M74-244, The MITRE
            Corporation, Bedford, MA, May 1973. (Available as AD-771543,
            National Technical Information Service, Springfield, VA.)

   [CCIB]   Common Criteria Implementation Board, "Common Criteria for
            Information Technology Security Evaluation, Part 1:
            Introduction and General Model", ver. 2.1, CCIB-99-01, Aug
            1999.

   [CIPSO]  Trusted Systems Interoperability Working Group, "Common IP
            Security Option", ver. 2.3, 9 Mar 1993. [A "work in
            progress" that is probably defunct.]

   [CSC1]   U.S. Department of Defense Computer Security Center,
            "Department of Defense Trusted Computer System Evaluation
            Criteria", CSC-STD-001-83, 15 Aug 1983. (Superseded by
            [DOD1].)

   [CSC2]   ---, "Department of Defense Password Management Guideline",
            CSC-STD-002-85, 12 Apr 1985.

   [CSC3]   ---, "Computer Security Requirements: Guidance for Applying
            the Department of Defense Trusted Computer System Evaluation
            Criteria in Specific Environments", CSC-STD-003-85, 25 Jun
            1985.

   [CSOR]   U.S. Department of Commerce, "General Procedures for
            Registering Computer Security Objects", National Institute
            of Standards Interagency Report 5308, Dec 1993.

   [Denn]   D. E. Denning, "A Lattice Model of Secure Information Flow",
            in "Communications of the ACM", vol. 19, no. 5, May 1976,
            pp. 236-243.

   [DH76]   W. Diffie and M. H. Hellman, "New Directions in
            Cryptography" in "IEEE Transactions on Information Theory",
            vol. IT-22, no. 6, Nov 1976, pp. 644-654.

   [DOD1]   U.S. Department of Defense, "Department of Defense Trusted
            Computer System Evaluation Criteria", DoD 5200.28-STD, 26
            Dec 1985. (Supersedes [CSC1].)

   [DOD2]   ---, Directive 5200.28, "Security Requirements for Automated
            Information Systems (AISs)", 21 Mar 1988.

   [DOD3]   ---, "X.509 Certificate Policy", ver. 2, Mar 1999.

   [DOD4]   ---, "NSA Key Recovery Assessment Criteria", 8 Jun 1998.

   [ElGa]   T. El Gamal, "A Public-Key Cryptosystem and a Signature
            Scheme Based on Discrete Logarithms" in "IEEE Transactions
            on Information Theory", vol. IT-31, no. 4, 1985, pp. 469-
            472.

   [EMV1]   Europay International S.A., MasterCard International
            Incorporated, and Visa International Service Association,
            "EMV '96 Integrated Circuit Card Specification for Payment
            Systems", ver. 3.1.1, 31 May 1998.

   [EMV2]   ---, "EMV '96 Integrated Circuit Card Terminal Specification
            for Payment Systems", ver. 3.1.1, 31 May 1998.

   [EMV3]   ---, EMV '96 Integrated Circuit Card Application
            Specification for Payment Systems", ver. 3.1.1, 31 May 1998.

   [For94]  W. Ford, "Computer Communications Security: Principles,
            Standard Protocols and Techniques", ISBN 0-13-799453-2,
            1994.

   [For97]  W. Ford and M. Baum, "Secure Electronic Commerce: Building
            the Infrastructure for Digital Signatures and Encryption",
            ISBN 0-13-476342-4, 1994.

   [FP031]  U.S. Department of Commerce, "Guidelines for Automatic Data
            Processing Physical Security and Risk Management", Federal
            Information Processing Standards Publication (FIPS PUB) 31,
            Jun 1974.

   [FP039]  ---, "Glossary for Computer Systems Security", FIPS PUB 39,
            15 Feb 1976.

   [FP046]  ---, "Data Encryption Standard (DES)", FIPS PUB 46-2, 30 Dec
            1993.

   [FP081]  ---, "DES Modes of Operation", FIPS PUB 81, 2 Dec 1980.

   [FP102]  ---, "Guideline for Computer Security Certification and
            Accreditation", FIPS PUB 102, 27 Sep 1983.

   [FP113]  ---, "Computer Data Authentication", FIPS PUB 113, 30 May
            1985.

   [FP140]  ---, "Security Requirements for Cryptographic Modules", FIPS
            PUB 140-1, 11 Jan 1994.

   [FP151]  ---, "Portable Operating System Interface (POSIX)--System
            Application Program Interface [C Language]", FIPS PUB 151-2,
            12 May 1993

   [FP180]  ---, "Secure Hash Standard", FIPS PUB 180-1, 17 Apr 1995.

   [FP185]  ---, "Escrowed Encryption Standard", FIPS PUB 185, 9 Feb
            1994.

   [FP186]  ---, "Digital Signature Standard (DSS)", FIPS PUB 186, 19
            May 1994.

   [FP188]  ---, "Standard Security Label for Information Transfer",
            FIPS PUB 188, 6 Sep 1994.

   [FPDAM]  Collaborative ITU and ISO/IEC meeting on the Directory,
            "Final Proposed Draft Amendment on Certificate Extensions",
            April 1999. (This draft proposes changes to [X.509].)

   [FPKI]   U.S. Department of Commerce, "Public Key Infrastructure
            (PKI) Technical Specifications: Part A--Technical Concept of
            Operations", National Institute of Standards, 4 Sep 1998.

   [I3166]  International Standards Organization, "Codes for the
            Representation of Names of countries and Their Subdivisions
            --Part 1: Country Codes", ISO 3166-1:1997.

            ---, --- "Part 2: Country Subdivision Codes", ISO/DIS 3166-
            2.

            ---, --- "Part 3: Codes for Formerly Used Names of
            Countries", ISO/DIS 3166-3.

   [I7498]  ---, "Information Processing Systems--Open Systems
            Interconnection Reference Model--[Part 1:] Basic Reference
            Model", ISO/IEC 7498-1. (Equivalent to ITU-T Recommendation
            X.200.)

            ---, --- "Part 2: Security Architecture", ISO/IEC 7499-2.

            ---, --- "Part 4: Management Framework", ISO/IEC 7498-4.

   [I7812]  ---, "Identification cards--Identification of Issuers--Part
            1: Numbering System", ISO/IEC 7812-1:1993

            ---, --- "Part 2: Application and Registration Procedures",
            ISO/IEC 7812-2:1993.

   [I9945]  ---, "Portable Operating System Interface for Computer
            Environments", ISO/IEC 9945-1:1990.

   [I15408] ---, "Information Technology--Security Techniques--
            Evaluation criteria for IT Security--Part 1: Introduction
            and General Model", ISO/IEC 15408-1:1999.

[ITSEC] "Information Technology Security Evaluation Criteria (ITSEC): Harmonised Criteria of France, Germany, the Netherlands, and the United Kingdom", ver. 1.2, U.K. Department of Trade and Industry, Jun 1991.

[Kahn] David Kahn, "The Codebreakers: The Story of Secret Writing", The Macmillan Company, New York, 1967.

[Knuth] D. E. Knuth, Chapter 3 ("Random Numbers") in Volume 2 ("Seminumerical Algorithms") of "The Art of Computer Programming", Addison-Wesley, Reading, MA, 1969.

[Kuhn] Markus G. Kuhn and Ross J. Anderson, "Soft Tempest: Hidden Data Transmission Using Electromagnetic Emanations", in David Aucsmith, ed., "Information Hiding, Second International Workshop, IH'98", Portland, Oregon, USA, 15-17 Apr 1998, LNCS 1525, Springer-Verlag, ISBN 3-540-65386-4, pp. 124-142.

[MISPC] U.S. Department of Commerce, "Minimum Interoperability Specification for PKI Components (MISPC), Version 1", National Institute of Standards Special Publication 800-15, Sep 1997.

[NCS01] National Computer Security Center, "A Guide to Understanding Audit in Trusted Systems", NCSC-TG-001, 1 Jun 1988. (Part of the Rainbow Series.)

[NCS04] ---, "Glossary of Computer Security Terms", NCSC-TG-004, ver. 1, 21 Oct 1988. (Part of the Rainbow Series.)

[NCS05] ---, "Trusted Network Interpretation of the Trusted Computer System Evaluation Criteria", NCSC-TG-005, ver. 1, 31 Jul 1987. (Part of the Rainbow Series.)

[NCS25] ---, "A Guide to Understanding Data Remanence in Automated Information Systems", NCSC-TG-025, ver. 2, Sep 1991. (Part of the Rainbow Series.)

[NIST] National Institute of Standards and Technology, "SKIPJACK and KEA Algorithm Specifications", ver. 2, 29 May 1998. (http://csrc.nist.gov/encryption/skipjack-kea.htm)

[PGP] Simson Garfinkel, "PGP: Pretty Good Privacy", O'Reilly & Associates, Inc., Sebastopol, CA, 1995.

[PKCS] Burton S. Kaliski, Jr., "An Overview of the PKCS Standards", RSA Data Security, Inc., 3 Jun 1991.

[PKC07] RSA Laboratories, "PKCS #7: Cryptographic Message Syntax Standard", ver. 1.5, RSA Laboratories Technical Note, 1 Nov 1993.

[PKC10] ---, "PKCS #10: Certification Request Syntax Standard", ver. 1.0, RSA Laboratories Technical Note, 1 Nov 1993.

[PKC11] ---, "PKCS #11: Cryptographic Token Interface Standard", ver. 1.0, 28 Apr 1995.

[R0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August 1980.

[R0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981.

[R0792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, September 1981. [See: RFC 1885.]

[R0793] Postel, J., ed., "Transmission Control Protocol", STD 7, RFC 793, September 1981.

[R0821] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821, August 1982.

[R0822] Crocker, D., "Standard for the Format of ARPA Internet Text Messages", STD 11, RFC 822, August 1982.

[R0854] Postel, J. and J. Reynolds, "TELNET Protocol Specification", STD 8, RFC 854, May 1983.

[R0959] Postel, J. and J. Reynolds, "File Transfer Protocol (FTP)", STD 9, RFC 959, October 1985.

[R1034] Mockapetris, P., "Domain Names--Concepts and Facilities", STD 13, RFC 1034, November 1987.

[R1157] Case, J., Fedor, M., Schoffstall, M. and J. Davin, "A Simple Network Management Protocol (SNMP)" [version 1], STD 15, RFC 1157, May 1990.

[R1208] Jacobsen O. and D. Lynch, "A Glossary of Networking Terms", RFC 1208, March 1991.

[R1319] Kaliski, B., "The MD2 Message-Digest Algorithm", RFC 1319, April 1992.

[R1320] Rivest, R., "The MD4 Message-Digest Algorithm", RFC 1320, April 1992.

[R1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, April 1992.

[R1334] Lloyd, B. and W. Simpson, "PPP Authentication Protocols", RFC 1334, October 1992.

[R1413] St. Johns, M., "Identification Protocol", RFC 1413, February 1993.

[R1421] Linn, J., "Privacy Enhancement for Internet Electronic Mail, Part I: Message Encryption and Authentication Procedures", RFC 1421, February 1993.

[R1422] Kent, S., "Privacy Enhancement for Internet Electronic Mail, Part II: Certificate-Based Key Management", RFC 1422, February 1993.

[R1455] Eastlake, D., "Physical Link Security Type of Service", RFC 1455, May 1993.

[R1457] Housley, R., "Security Label Framework for the Internet", RFC 1457, May 1993.

[R1492] Finseth, C., "An Access Control Protocol, Sometimes Called TACACS", RFC 1492, July 1993.

[R1507] Kaufman, C., "DASS: Distributed Authentication Security Service", RFC 1507, September 1993.

[R1510] Kohl, J. and C. Neuman, "The Kerberos Network Authentication Service (V5)", RFC 1510, September 1993.

[R1591] Kohl, J. and C. Neuman, "Domain Name System Structure and Delegation", March 1994.

[R1630] Berners-Lee, T., "Universal Resource Identifiers in WWW", RFC 1630, June 1994.

[R1661] Simpson, W., ed., "The Point-to-Point Protocol (PPP)", STD 51, RFC 1661, July 1994.

[R1731] Myers, J., "IMAP4 Authentication Mechanisms", RFC 1731, December 1994.

[R1734] Myers, J., "POP3 AUTHentication Command", RFC 1734, December 1994.

[R1738] Myers, J., Masinter, L. and M. McCahill, ed's., "Uniform Resource Locators (URL)", RFC 1738, December 1994.

[R1750] Eastlake, D., Crocker, S. and J. Schiller, "Randomness Recommendations for Security", RFC 1750, December 1994.

[R1777] Yeong, W., Howes, T. and S. Kille, "Lightweight Directory Access Protocol", RFC 1777, March 1995.

[R1808] Fielding, R., "Relative Uniform Resource Locators", RFC 1808, June 1995.

[R1824] Danisch, H., "The Exponential Security System TESS: An Identity-Based Cryptographic Protocol for Authenticated Key-Exchange (E.I.S.S.-Report 1995/4)", RFC 1824, August 1995.

[R1828] Metzger, P. and W. Simpson, "IP Authentication using Keyed MD5", RFC 1828, August 1995.

[R1829] Karn, P., Metzger, P. and W. Simpson, "The ESP DES-CBC Transform", RFC 1829, August 1995.

[R1848] Crocker, S., Freed, N., Galvin, J. and S. Murphy, "MIME Object Security Services", RFC 1848, October 1995.

[R1851] Karn, P., Metzger, P. and W. Simpson, "The ESP Triple DES Transform", RFC 1851, September 1995.

[R1866] Berners-Lee, T., "Hypertext Markup Language--2.0", RFC 1866, November 1995.

[R1885] Conta, A. and S. Deering, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC 1885, December 1995.

[R1928] Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D. and L. Jones, "SOCKS Protocol Version 5", RFC 1928, March 1996.

[R1938] Haller, N. and C. Metzion, "A One-Time Password System", RFC 1938, May 1996.

[R1939] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD 53, RFC 1939, May 1996.

[R1958] Carpenter, B., ed., "Architectural Principles of the Internet", RFC 1958, June 1996.

[R1983] Malkin, G., ed., "Internet Users' Glossary", FYI 18, RFC 1983, August 1996.

[R1994] Simpson, W. "PPP Challenge Handshake Authentication Protocol (CHAP)", RFC 1994, August 1996.

[R2023] Postel, J. and J. Reynolds, "Instructions to RFC Authors", RFC 2023, October 1997.

[R2026] Bradner, S., "The Internet Standards Process--Revision 3", BCP 9, RFC 2026, March 1994.

[R2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996.

[R2060] Crispin, M., "Internet Message Access Protocol--Version 4 Revision 1", RFC 2060, December 1996.

[R2065] Eastlake, D., 3rd, "Domain Name System Security Extensions", RFC 2065, January 1997.

[R2078] Linn, J., "Generic Security Service Application Program Interface, Version 2", RFC 2078, January 1997.

[R2084] Bossert, G., Cooper, S. and W. Drummond, "Considerations for Web Transaction Security", RFC 2084, January 1997.

[R2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: Keyed-Hashing for Message Authentication", RFC 2104, February 1997.

[R2119] Bradner, S., "Key Words for Use in RFCs To Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.

[R2138] Rigney, C., Rubens, A., Simpson, W. and S. Willens, "Remote Authentication Dial In User Service (RADIUS)", RFC 2138, April 1997.

[R2137] Eastlake, D., "Secure Domain Name System Dynamic Update", RFC 2137, April 1997.

[R2179] Gwinn, A., "Network Security For Trade Shows", RFC 2179, July 1997.

[R2195] Klensin, J., Catoe, R. and P. Krumviede, "IMAP/POP AUTHorize Extension for Simple Challenge/Response", RFC 2195, Sepember 1997.

[R2196] Fraser, B., "Site Security Handbook", FYI 8, RFC 2196, Sepember 1997.

[R2202] Cheng, P. and R. Glenn, "Test Cases for HMAC-MD5 and HMAC-SHA-1", RFC 2202, Sepember 1997.

[R2222] Myers, J., "Simple Authentication and Security Layer (SASL)", RFC 2222, October 1997.

[R2223] Postel, J., "Instructions to RFC Authors", RFC 2223, October 1997.

[R2246] Dierks, T. and C. Allen, "The TLS Protocol, Version 1.0", RFC 2246, January 1999.

[R2284] Blunk, L. and J. Vollbrecht, "PPP Extensible Authentication Protocol (EAP)", RFC 2284, March 1998.

[R2315] Kaliski, B., "PKCS #7: Cryptographic Message Syntax, Version 1.5", RFC 2315, March 1998.

[R2323] Ramos, A., "IETF Identification and Security Guidelines", RFC 2323, 1 April 1998. [Intended for humorous entertainment ("please laugh loud and hard"); does not contain serious security information.]

[R2350] Brownlee, N. and E. Guttman, "Expectations for Computer Security Incident Response", RFC 2350, June 1998.

[R2356] Montenegro, C. and V. Gupta, "Sun's SKIP Firewall Traversal for Mobile IP", RFC 2356, June 1998.

[R2373] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 2373, July 2998.

[R2401] Kent, S. and R. Atkinson, "Security Architecture for the Internet Protocol", RFC 2401, November 1998.

[R2402] Kent, S. and R. Atkinson, "IP Authentication Header", RFC 2402, November 1998.

[R2403] Madson, C. and R. Glenn, "The Use of HMAC-MD5-96 within ESP and AH", RFC 2403, November 1998.

[R2404] Madson, C. and R. Glenn, "The Use of HMAC-SHA-1-96 within ESP and AH", RFC 2404, November 1998.

[R2405] Madson, C. and N. Doraswamy, "The ESP DES-CBC Cipher Algorithm With Explicit IV", RFC 2405, November 1998.

[R2406] Kent, S. and R. Atkinson, "IP Encapsulating Security Payload (ESP)", RFC 2406, November 1998.

[R2407] Piper, D., "The Internet IP Security Domain of Interpretation for ISAKMP", RFC 2407, November 1998.

[R2408] Maughan, D., Schertler, M., Schneider, M. and J. Turner, "Internet Security Association and Key Management Protocol (ISAKMP)", RFC 2408, November 1998. 🔐
[R2409] Harkins, D. and D. Carrel, "The Internet Key Exchange (IKE)", RFC 2409, November 1998. 🗝️
[R2410] Glenn, R. and S. Kent, "The NULL Encryption Algorithm and Its Use With IPsec", RFC 2410, November 1998.
[R2412] Orman, H., "The OAKLEY Key Determination Protocol", RFC 2412, November 1998.
[R2451] Pereira, R. and R. Adams, "The ESP CBC-Mode Cipher Algorithms", RFC 2451, November 1998.
[R2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. 🌐
[R2504] Guttman, E., Leong, L. and G. Malkin, "Users' Security Handbook", RFC 2504, February 1999.
[R2510] Adams, C. and S. Farrell, "Internet X.509 Public Key Infrastructure Certificate Management Protocols", RFC 2510, March 1999.
[R2527] Chokhani, S. and W. Ford, "Internet X.509 Public Key Infrastructure, Certificate Policy and Certification Practices Framework", RFC 2527, March 1999.
[R2536] EastLake, D., "DSA KEYs and SIGs in the Domain Name System (DNS)", RFC 2536, March 1999.
[R2570] Case, J., Mundy, R., Partain, D. and B. Stewart, "Introduction to Version 3 of the Internet-Standard Network Management Framework", RFC 2570, April 1999.
[R2574] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for Version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2574, April 1999.
[R2612] Adams, C. and J. Gilchrist, "The CAST-256 Encryption Algorithm", RFC 2612, June 1999.
[R2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol-- HTTP/1.1", RFC 2616, June 1999.
[R2628] Smyslov, V., "Simple Cryptographic Program Interface", RFC 2628, June 1999.
[R2630] Housley, R., "Cryptographic Message Syntax", RFC 2630, June 1999.
[R2631] Rescorla, E., "Diffie-Hellman Key Agreement Method", RFC 2631, June 1999.
[R2633] Ramsdell, B., ed., "S/MIME Version 3 Message Specification", RFC 2633, June 1999.
[R2634] Hoffman, P., ed., "Enhanced Security Services for S/MIME", RFC 2634, June 1999.
[R2635] Hambridge, S. and A. Lunde, "Don't Spew: A Set of Guidelines for Mass Unsolicited Mailings and Postings", RFC 2635, June 1999. 📧
[Raym] E. S. Raymond, ed., "The On-Line Hacker Jargon File", ver. 4.0.0, 24 Jul 1996. (Also available as "The New Hacker's Dictionary", 2nd edition, MIT Press, Sep 1993, ISBN 0-262-18154-1. See: http://www.tuxedo.org/jargon/ for the latest version.) 💻
[Russ] D. Russell and G. T. Gangemi Sr., Chapter 10 ("TEMPEST") in "Computer Security Basics", ISBN 0-937175-71-4, 1991.
[Schn] B. Schneier, "Applied Cryptography", John Wiley & Sons, Inc., New York, 1994. 📚
[SDNS3] U.S. Department of Defense, National Security Agency, "Secure Data Network Systems, Security Protocol 3 (SP3)", document SDN.301, Revision 1.5, 15 May 1989.
[SDNS4] ---, ---, "Security Protocol 4 (SP4)", document SDN.401, Revision 1.2, 12 Jul 1988.
[SDNS7] ---, ---, "Secure data Network System, Message Security Protocol (MSP)", document SDN.701, Revision 4.0, 7 Jun 1996, with Corrections to Message Security Protocol, SDN.701, Rev 4.0", 96-06-07, 30 Aug, 1996.
[SET1] MasterCard and Visa, "SET Secure Electronic Transaction Specification, Book 1: Business Description", ver. 1.0, 31 May 1997. 💳
[SET2] ---, "SET Secure Electronic Transaction Specification, Book 2: Programmer's Guide", ver. 1.0, 31 May 1997.
[Stei] J. Steiner, C. Neuman, and J. Schiller, "Kerberos: An Authentication Service for Open Network Systems" in "Usenix Conference Proceedings", Feb 1988. 🎫
[X400] International Telecommunications Union--Telecommunication Standardization Sector (formerly "CCITT"), Recommendation X.400, "Message Handling Services: Message Handling System and Service Overview".
[X500] ---, Recommendation X.500, "Information Technology--Open Systems Interconnection--The Directory: Overview of Concepts, Models, and Services". (Equivalent to ISO 9594-1.)
[X501] ---, Recommendation X.501, "Information Technology--Open Systems Interconnection--The Directory: Models".
[X509] ---, Recommendation X.509, "Information Technology--Open Systems Interconnection--The Directory: Authentication Framework". (Equivalent to ISO 9594-8.)
[X519] ---, Recommendation X.519, "Information Technology--Open Systems Interconnection--The Directory: Protocol Specifications".
[X520] ---, Recommendation X.520, "Information Technology--Open Systems Interconnection--The Directory: Selected Attribute Types".
[X680] ---, Recommendation X.680, "Information Technology--Abstract Syntax Notation One (ASN.1)--Specification of Basic Notation", 15 Nov 1994. (Equivalent to ISO/IEC 8824-1.)
[X690] ---, Recommendation X.690, "Information Technology--ASN.1 Encoding Rules--Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)", 15 Nov 1994. (Equivalent to ISO/IEC 8825-1.)

5. Security Considerations 🛡️✨

okay bestie, this one is short but it's a whole vibe 💅 This document only defines security terms and recommends how to use them. It does NOT go deep into the vulnerabilities of, threats to, or the mechanisms that protect specific Internet protocols. So if you're looking for the juicy "how do I lock down protocol X" details, you'll need to go find them somewhere else 🙈

6. Acknowledgments 🫶

Shoutout to Pat Cain, Mike Kong, and Charles Lynn, who gave meticulous comments on an early draft. Absolute legends 💖

7. Author's Address 📮

Please send all comments to:

Robert W. Shirey                   GTE / BBN Technologies
EMail: rshirey@bbn.com             Suite 1200, Mail Stop 30/12B2
Phone: +1 (703) 284-4641           1300 Seventeenth Street North
Fax:   +1 (703) 284-2766           Arlington, VA  22209-3801 USA

8. Full Copyright Statement 🌈

okay so the vibe here is: you can copy and share this document, and you can make derivative works that comment on it, explain it, or help people implement it, as long as the copyright notice and this paragraph stay on every copy. But this document itself may not be modified in any way, such as by removing the copyright notice or the references to the Internet Society or other Internet organizations. The exceptions are when it's needed for developing Internet standards (then the copyright procedures in the Internet Standards process must be followed), or when it's being translated into languages other than English.

The limited permissions above are perpetual and will not be revoked by the Internet Society or its successors or assigns. 🔒

This document and the information in it is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 😭

Acknowledgement 🎀

Funding for the RFC Editor function is currently provided by the Internet Society. Thank you for keeping the lights on, Internet Society 🌸

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