tpm2_certifycreation(1)

🫶 tpm2_certifycreation(1) 🫶

Straight from the General Commands Manual, bestie — this is the whole vibe. 💅

✨ NAME ✨

tpm2_certifycreation(1) — attest the association between a loaded public area and the provided hash of the creation data. 💖

🌸 SYNOPSIS 🌸

tpm2_certifycreation [OPTIONS]

🦋 DESCRIPTION 🦋

Okay so tpm2_certifycreation(1) is here to attest the association between a loaded public area and the provided hash of the creation data. The creation data and the creation ticket are produced when creating the object. The object itself is created with either TPM2_CreatePrimary or TPM2_Create commands. No cap, that’s the whole point. ✨

💅 OPTIONS 💅

• -C, --signingkey-context=OBJECT — Context object pointing to the key used that signs the attestation. 🔑
• -P, --signingkey-auth_AUTH_ — Optional authorization value to use for the key specified by -C.
• -c, --certifiedkey-context=OBJECT — Context object pointing to the key that has to be certified. 👑
• -g, --hash-algorithm=ALGORITHM — The hash algorithm used to digest the creation data.
• -s, --scheme=ALGORITHM — The signing scheme used to sign the attestation data.
• -d, --creation-hash=FILE — File containing the digest of the creation data.
• -t, --ticket=FILE — The ticket file to validate that the creation data was produced by the TPM. 🎟️
• -o, --signature=FILE — File containing the signature of the attestation data for the certified key.
• -f, --format=FORMAT — Output signature format selection.
• –attestation=FILE — The attestation data of the type TPM2_CREATION_INFO signed with signing key.
• -q, --qualification=FILE_OR_HEX — Optional, the policy qualifier data that the signer can choose to include in the signature. Can either be a path or hex string.
• --cphash=FILE — File path to record the hash of the command parameters. This is commonly termed as cpHash. NOTE: When this option is selected, The tool will not actually execute the command, it simply returns a cpHash, unless rphash is also required. 👀
• --rphash=FILE — File path to record the hash of the response parameters. This is commonly termed as rpHash.
• -S, --session=FILE — The session created using tpm2_startauthsession. This can be used to specify an auxiliary session for auditing and or encryption/decryption of the parameters. 🔐

🌈 References 🌈

🧸 Context Object Format 🧸

The type of a context object, whether it is a handle or file name, is determined according to the following logic in-order:

• If the argument is a file path, then the file is loaded as a restored TPM transient object.
• If the argument is a prefix match on one of:
  • owner: the owner hierarchy
  • platform: the platform hierarchy
  • endorsement: the endorsement hierarchy
  • lockout: the lockout control persistent object
• If the argument argument can be loaded as a number it will be treat as a handle, e.g. 0x81010013 and used directly. _OBJECT_

💖 Authorization Formatting 💖

Authorization for use of an object in TPM2.0 can come in 3 different forms:

1. Password
2. HMAC
3. Sessions

NOTE: “Authorizations default to the EMPTY PASSWORD when not specified”.

For authentication with auth values, the tool commands implicitly generate an HMAC session. Thus passwords are not transmitted unencrypted. This does not apply to passwords defined for objects. In this case, an HMAC session should be used (see tpm2_startauthsession(1)). 🫶

🍓 Passwords 🍓

Passwords are interpreted in the following forms below using prefix identifiers.

Note: By default passwords are assumed to be in the string form when they do not have a prefix.

✨ String ✨

A string password, specified by prefix “str:” or it’s absence (raw string without prefix) is not interpreted, and is directly used for authorization.

🌟 Examples 🌟

foobar
str:foobar

🧚 Hex-string 🧚

A hex-string password, specified by prefix “hex:” is converted from a hexidecimal form into a byte array form, thus allowing passwords with non-printable and/or terminal un-friendly characters. 🔥

🎀 Example 🎀

hex:1122334455667788

🦋 File 🦋

A file based password, specified be prefix “file:” should be the path of a file containing the password to be read by the tool or a “-” to use stdin. Storing passwords in files prevents information leakage, passwords passed as options can be read from the process list or common shell history features. 🙈

🌸 Examples 🌸

# to use stdin and be prompted
file:-

# to use a file from a path
file:path/to/password/file

# to echo a password via stdin:
echo foobar | tpm2_tool -p file:-

# to use a bash here-string via stdin:

tpm2_tool -p file:- <<< foobar

💜 Sessions 💜

When using a policy session to authorize the use of an object, prefix the option argument with the session keyword. Then indicate a path to a session file that was created with tpm2_startauthsession(1). Optionally, if the session requires an auth value to be sent with the session handle (eg policy password), then append a + and a string as described in the Passwords section.

⭐ Examples ⭐

To use a session context file called session.ctx.

session:session.ctx

To use a session context file called session.ctx AND send the authvalue mypassword.

session:session.ctx+mypassword

To use a session context file called session.ctx AND send the HEX authvalue 0x11223344.

session:session.ctx+hex:11223344

🧬 PCR Authorizations 🧬

You can satisfy a PCR policy using the “pcr:” prefix and the PCR minilanguage. The PCR minilanguage is as follows:

<pcr-spec>=<raw-pcr-file>

The PCR spec is documented in in the section “PCR bank specifiers”.

The raw-pcr-file is an optional argument that contains the output of the raw PCR contents as returned by tpm2_pcrread(1).

🧪 PCR bank specifiers 🧪

🌈 Examples 🌈

To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifier of:

pcr:sha256:0,1,2,3

specifying AUTH.

👑 Algorithm Specifiers 👑

Options that take algorithms support “nice-names”.

There are two major algorithm specification string classes, simple and complex. Only certain algorithms will be accepted by the TPM, based on usage and conditions.

🎀 Simple specifiers 🎀

These are strings with no additional specification data. When creating objects, non-specified portions of an object are assumed to defaults. You can find the list of known “Simple Specifiers” below.

💙 Asymmetric 💙

• rsa
• ecc

💚 Symmetric 💚

• aes
• camellia
• sm4

💛 Hashing Algorithms 💛

• sha1
• sha256
• sha384
• sha512
• sm3_256
• sha3_256
• sha3_384
• sha3_512

🧡 Keyed Hash 🧡

• hmac
• xor

💜 Signing Schemes 💜

• rsassa
• rsapss
• ecdsa
• ecdaa
• ecschnorr
• sm2

🩵 Asymmetric Encryption Schemes 🩵

• oaep
• rsaes
• ecdh

🤍 Modes 🤍

• ctr
• ofb
• cbc
• cfb
• ecb

🖤 Misc 🖤

• null

🦄 Complex Specifiers 🦄

Objects, when specified for creation by the TPM, have numerous algorithms to populate in the public data. Things like type, scheme and asymmetric details, key size, etc. Below is the general format for specifying this data:

<type>:<scheme>:<symmetric-details>

🐚 Type Specifiers 🐚

This portion of the complex algorithm specifier is required. The remaining scheme and symmetric details will default based on the type specified and the type of the object being created.

• aes — Default AES: aes128
• aes128<mode> — 128 bit AES with optional mode (ctr|ofb|cbc|cfb|ecb). If mode is not specified, defaults to null.
• aes192<mode> — Same as aes128<mode>, except for a 192 bit key size.
• aes256<mode> — Same as aes128<mode>, except for a 256 bit key size.
• sm4 — Default SM4: sm4128
• sm4128 or sm4_128 <mode> — 128 bit SM4 with optional mode (ctr|ofb|cbc|cfb|ecb). If mode is not specified, defaults to null.
• ecc — Elliptical Curve, defaults to ecc256.
• ecc192 or ecc_nist_p192 — 192 bit ECC NIST curve
• ecc224 or ecc_nist_p224 — 224 bit ECC NIST curve
• ecc256 or ecc_nist_p256 — 256 bit ECC NIST curve
• ecc384 or ecc_nist_p384 — 384 bit ECC NIST curve
• ecc521 or ecc_nist_p521 — 521 bit ECC NIST curve
• ecc_sm2 or ecc_sm2_p256 — 256 bit SM2 curve
• rsa — Default RSA: rsa2048
• rsa1024 — RSA with 1024 bit keysize.
• rsa2048 — RSA with 2048 bit keysize.
• rsa3072 — RSA with 3072 bit keysize.
• rsa4096 — RSA with 4096 bit keysize.

🌟 Scheme Specifiers 🌟

Next, is an optional field, it can be skipped.

Schemes are usually Signing Schemes or Asymmetric Encryption Schemes. Most signing schemes take a hash algorithm directly following the signing scheme. If the hash algorithm is missing, it defaults to sha256. Some take no arguments, and some take multiple arguments.

🌸 Hash Optional Scheme Specifiers 🌸

These scheme specifiers are followed by a dash and a valid hash algorithm, For example: oaep-sha256.

• oaep
• ecdh
• rsassa
• rsapss
• ecdsa
• ecschnorr
• sm2

🦋 Multiple Option Scheme Specifiers 🦋

This scheme specifier is followed by a count (max size UINT16) then followed by a dash(-) and a valid hash algorithm.

• ecdaa — For example, ecdaa4-sha256. If no count is specified, it defaults to 4.

🧸 No Option Scheme Specifiers 🧸

This scheme specifier takes NO arguments.

• rsaes

🫧 Symmetric Details Specifiers 🫧

This field is optional, and defaults based on the type of object being created and it’s attributes. Generally, any valid Symmetric specifier from the Type Specifiers list should work. If not specified, an asymmetric objects symmetric details defaults to aes128cfb.

💫 Examples 💫

🌈 Create an rsa2048 key with an rsaes asymmetric encryption scheme 🌈

tpm2_create -C parent.ctx -G rsa2048:rsaes -u key.pub -r key.priv

🎀 Create an ecc256 key with an ecdaa signing scheme with a count of 4 and sha384 hash 🎀

/tpm2_create -C parent.ctx -G ecc256:ecdaa4-sha384 -u key.pub -r key.priv cryptographic algorithms ALGORITHM.

🌸 COMMON OPTIONS 🌸

okay so this lil bundle of options shows up in loadsss of the tools, they're the basics everyone expects 💅

• -h, --help=[man|no-man] — shows you the tool's manpage. by default it tries to fire up the manpager for the tool, but if that flops it just spits out a short tool summary instead. same behaviour if you literally pass the man argument, except if you explicitly ask for man then the tool will pass along errors from man on stderr. and if you say no-man, or the manpager fails, the short options go to stdout 🎀

heads up bestie: for the manpage feature to actually work the manpages need to be installed or chillin' on MANPATH — see man(1) for the deets.

• -v, --version — prints version info for this tool plus the supported tctis, then dips ✨
• -V, --verbose — makes the tool yap more to the console while it's running. with this one on, the file and line number get printed too 👀
• -Q, --quiet — silences the normal tool output to stdout 🤫
• -Z, --enable-errata — turns on errata fixups. super useful if an errata fixup needs to be applied to commands sent to the TPM. setting the env var TPM2TOOLS_ENABLE_ERRATA does the exact same thing, iykyk.
• -z, --pwd-session — uses a password session instead of a HMAC session for authentication. a clear text password gets passed to the TPM to authorize the action. this one's your girl when you wanna dodge problems with unsalted sessions in OpenSSL FIPS mode. but fr fr — if auth values are in play, use a salted session for authentication 🔥
• -R, --autoflush — enables autoflush for transient objects created by the command. if a parent object is loaded from a context file, the transient parent object gets flushed too. autoflush can also be activated if the environment variable TPM2TOOLS_AUTOFLUSH is set to yes or true. information many users may expect. 💫

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🦋 TCTI Configuration 🦋

the TCTI — aka the "Transmission Interface" — is literally the communication mechanism with the TPM. TCTIs can be swapped out so you can talk to TPMs across different mediums, no cap 🌈

to control the TCTI, the tools respect:

1. the command line option -T or --tcti
2. the environment variable TPM2TOOLS_TCTI

note: the command line option ALWAYS overrides the environment variable. periodt. 👑

the current known TCTIs are:

• tabrmd — the resource manager, called tabrmd. note that tabrmd and abrmd as a tcti name are synonymous 🫶
• mssim — typically used for communicating to the TPM software simulator.
• device — used when talking directly to a TPM device file.
• none — do NOT initialize a connection with the TPM. some tools allow for off-tpm options and thus support not using a TCTI. tools that don't support it will error out when you try to use them without a TCTI connection. this one does NOT support ANY options and MUST BE presented as the exact text none. no wiggle room bestie 💀

the arguments to either the command line option or the environment variable are in the form:

<tcti-name>:<tcti-option-config>

specifying an empty string for either the <tcti-name> or the <tcti-option-config> results in the default being used for that portion respectively ✨

💜 TCTI Defaults 💜

when a TCTI isn't specified, the default TCTI gets searched for using dlopen(3) semantics. the tools search for tabrmd, device and mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND 🔥 you can query what TCTI will be picked as the default by using the -v option to print the version information — the default-tcti key-value pair tells you which of the aforementioned TCTIs is the default 👀

🎀 Custom TCTIs 🎀

any TCTI that implements the dynamic TCTI interface can be loaded. the tools internally use dlopen(3), and the raw tcti-name value is used for the lookup. so this could be a path to the shared library, or a library name as understood by dlopen(3) semantics 🌟

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💅 TCTI OPTIONS 💅

this collection of options configures the various known TCTI modules available:

• device: for the device TCTI, you can specify the TPM character device file for use by the device TCTI. the default is /dev/tpm0 🍓

example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="device:/dev/tpm0"

• mssim: for the mssim TCTI, you can specify the domain name or IP address and port number used by the simulator. the defaults are 127.0.0.1 and 2321 ⭐

example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TCTI="mssim:host=localhost,port=2321"

• abrmd: for the abrmd TCTI, the configuration string format is a series of simple key value pairs separated by a , character. each key and value string are separated by a = character 🧚
  • the TCTI abrmd supports two keys:
    1. bus_name : the name of the tabrmd service on the bus (a string).
    2. bus_type : the type of the dbus instance (a string) limited to session and system.

specify the tabrmd tcti name and a config string of bus_name=com.example.FooBar:

--tcti=tabrmd:bus_name=com.example.FooBar

specify the default (abrmd) tcti and a config string of bus_type=session:

--tcti:bus_type=session

NOTE: abrmd and tabrmd are synonymous. the various known TCTI modules. 💀

✨ Signature Format Specifiers ✨

format selection for the signature output file. tss (the default) will output a binary blob according to the TPM 2.0 specification and any potential compiler padding. the plain option will output the plain signature data as defined by the used cryptographic algorithm 💖

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🌈 EXAMPLES 🌈

Certify creation data of a primary key.

tpm2_createprimary -C o -c prim.ctx --creation-data create.dat \
-d create.dig -t create.ticket

tpm2_create -G rsa -u rsa.pub -r rsa.priv -C prim.ctx -c signing_key.ctx

tpm2_certifycreation -C signing_key.ctx -c prim.ctx -d create.dig \
-t create.ticket -g sha256 -o sig.nature --attestation attestat.ion -f plain \
-s rsassa

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🔥 Returns 🔥

tools can return any of these codes, bestie:

• 0 — success 🎉
• 1 — general non-specific error 😭
• 2 — options handling error 🙈
• 3 — authentication error 🔐
• 4 — TCTI related error 💀
• 5 — non supported scheme. applicable to tpm2_testparams.

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🦋 BUGS 🦋

Github Issues 👑

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💜 HELP 💜

See the Mailing List 🫶

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🌸 License 🌸

this work is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0) — slay, legally speaking 💅

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and that's the whole page, bestie!! brought to you by tpm2-tools, aka the tpm2_certifycreation(1) manual page — go certify some creation data and stan a primary key for me 💖✨🎀