RFC 7192

Algorithms for Cryptographic Message Syntax (CMS) Key Package Receipt and Error Content Types

📅 published April 2014, from ietf

RFC 7192: Algorithms for Cryptographic Message Syntax (CMS) Key Package Receipt and Error Content Types 🎀

okay bestie, this one is literally the glue doc 💅 It's by Sean Turner of IECA, it's a Standards Track doc from April 2014 ✨, and it doesn't obsolete or update anything. It just sits there being the algorithm checklist for the key package receipt and error content types from RFC 7191. Nothing here is brand new, it just tells you which existing crypto to pick. 🫶

Its author address is IECA, Inc., 3057 Nutley Street, Suite 106, Fairfax, VA 22031, USA, and the email is turners@ieca.com 💌

Here is the original title block, kept as it was:

Internet Engineering Task Force (IETF)                         S. Turner
Request for Comments: 7192                                          IECA
Category: Standards Track                                     April 2014
ISSN: 2070-1721

Abstract ✨

so the vibe is: this doc explains how to use a bunch of crypto algorithms with the CMS key package receipt and error content types. It covers the stuff you need to implement SignedData, EnvelopedData, EncryptedData, and AuthEnvelopedData. 💖

Status of This Memo 📜

This is an Internet Standards Track document. 🌸

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. 🧚

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7192. 🦋

Copyright Notice ©️

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. read the fine print, it's the boring-but-important part 🙈

1. Introduction 🍓

This document describes the conventions for using several cryptographic algorithms with the Cryptographic Message Syntax (CMS) key package receipt and error content types [RFC7191]. Specifically, it includes conventions necessary to implement SignedData [RFC5652], EnvelopedData [RFC5652], EncryptedData [RFC5652], and AuthEnvelopedData [RFC5083]. ✨

This document does not define any new algorithms. it just points at algorithms that already exist 🌈 The algorithm requirements here are the same as the ones in [RFC5959], [RFC6033], [RFC6160], [RFC6161], and [RFC6162], with these exceptions: the content-encryption algorithm is AES in Cipher Block Chaining (CBC) mode, as opposed to AES Key Wrap with Message Length Indicator (MLI), and the key-wrap algorithm is AES Key Wrap, as opposed to AES Key Wrap with MLI. 💅

The reason is that the receipt and error content types are not keys, so AES Key Wrap with MLI is not appropriate for the content-encryption algorithm. If an implementation is not using AES Key Wrap with MLI as the content-encryption algorithm, then there's no need to keep the key-wrap algorithm the same as the content encryption algorithm. 🧁

NOTE: [RFC7191] only requires that the key package receipt be signed. 🚨

1.1. Terminology 🔥

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 🎀

2. SignedData 🌷

If an implementation supports SignedData, then it MUST support the signature scheme RSA [RFC3370] and SHOULD support the signature schemes RSA Probabilistic Signature Scheme (RSASSA-PSS) [RFC4056] and Digital Signature Algorithm (DSA) [RFC3370]. Additionally, implementations MUST support the hash function SHA-256 [RFC5754] in concert with these signature schemes, and they SHOULD support the hash function SHA-1 [RFC3370]. Implementations can also choose the to support Elliptic Curve Digital Signature Algorithm (ECDSA) [RFC5753] and [RFC6090]. 🦋

3. EnvelopedData 🧚

If an implementation supports EnvelopedData, then it MUST implement key transport and it MAY implement key agreement. 🌸

When key transport is used, RSA encryption [RFC3370] MUST be supported, and RSA Encryption Scheme - Optimal Asymmetric Encryption Padding (RSAES-OAEP) [RFC3560] SHOULD be supported. 💜

When key agreement is used, Diffie-Hellman (DH) ephemeral-static [RFC3370] MUST be supported. When key agreement is used, Elliptic Curve Diffie-Hellman (ECDH) [RFC5753] [RFC6090] MAY be supported. ✨

Regardless of the key management technique choice, implementations MUST support AES-128 in CBC mode [AES] as the content-encryption algorithm. Implementations SHOULD support AES-256 in CBC mode [AES] as the content-encryption algorithm. 🔥

When key agreement is used, the same length for the underlying block algorithm MUST be used. If the content-encryption algorithm is AES-128 in CBC mode, then the key-wrap algorithm MUST be AES-128 Key Wrap [RFC3394]. If the content-encryption algorithm is AES-256 in CBC mode, then the key-wrap algorithm MUST be AES-256 Key Wrap [RFC3394]. 🎀

4. EncryptedData 💖

If an implementation supports EncryptedData, then it MUST implement AES-128 in CBC mode [AES] and SHOULD implement AES-256 in CBC mode [AES]. 🌈

NOTE: EncryptedData requires that keys be managed by other means; therefore, the only algorithm specified is the content-encryption algorithm. 🙈

5. AuthEnvelopedData 🫶

If an implementation supports AuthEnvelopedData, then it MUST implement the EnvelopedData recommendations except for the content-encryption algorithm, which, in this case, MUST be AES-GCM [RFC5084]; the 128-bit version MUST be implemented, and the 256-bit version SHOULD be implemented. Implementations MAY also support AES-CCM [RFC5084]. 🍓

6. Public Key Sizes 🔑

The easiest way to implement SignedData, EnvelopedData, and AuthEnvelopedData is with public key certificates [RFC5280]. If an implementation supports RSA, RSASSA-PSS, DSA, RSAES-OAEP, or Diffie-Hellman, then it MUST support key lengths from 1024-bit to 2048-bit, inclusive. If an implementation supports ECDSA or ECDH, then it MUST support keys on the P-256 curve [RFC6090]. 👑

7. Security Considerations 🚨

this part is serious, so read it closely 😭

The security considerations from [RFC3370], [RFC3394], [RFC3560], [RFC4056], [RFC5084], [RFC5652], [RFC5753], and [RFC5754] apply. 💀

[SP800-57] provides comparable bits of security for some algorithms and key sizes. [SP800-57] also provides time frames during which certain numbers of bits of security are appropriate, and some environments may find these time frames useful. 🌸

8. Acknowledgements 💌

I'd like to thank Russ Housley for his early feedback on this document. 🫶

9. References 📚

9.1. Normative References 💜

[AES]      National Institute of Standards and Technology, FIPS Pub
           197: Advanced Encryption Standard (AES), 26 November 2001.

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC3370]  Housley, R., "Cryptographic Message Syntax (CMS)
           Algorithms", RFC 3370, August 2002.

[RFC3394]  Schaad, J. and R. Housley, "Advanced Encryption Standard
           (AES) Key Wrap Algorithm", RFC 3394, September 2002.

[RFC3560]  Housley, R., "Use of the RSAES-OAEP Key Transport
           Algorithm in Cryptographic Message Syntax (CMS)", RFC
           3560, July 2003.

[RFC4056]  Schaad, J., "Use of the RSASSA-PSS Signature Algorithm in
           Cryptographic Message Syntax (CMS)", RFC 4056, June 2005.

[RFC5083]  Housley, R., "Cryptographic Message Syntax (CMS)
           Authenticated-Enveloped-Data Content Type", RFC 5083,
           November 2007.

[RFC5084]  Housley, R., "Using AES-CCM and AES-GCM Authenticated
           Encryption in the Cryptographic Message Syntax (CMS)", RFC
           5084, November 2007.

[RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
           Housley, R., and W. Polk, "Internet X.509 Public Key
           Infrastructure Certificate and Certificate Revocation List
           (CRL) Profile", RFC 5280, May 2008.

[RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
           RFC 5652, September 2009.

[RFC5753]  Turner, S. and D. Brown, "Use of Elliptic Curve
           Cryptography (ECC) Algorithms in Cryptographic Message
           Syntax (CMS)", RFC 5753, January 2010.

[RFC5754]  Turner, S., "Using SHA2 Algorithms with Cryptographic
           Message Syntax", RFC 5754, January 2010.

[RFC6090]  McGrew, D., Igoe, K., and M. Salter, "Fundamental Elliptic
           Curve Cryptography Algorithms", RFC 6090, February 2011.

[RFC7191]  Housley, R., "Cryptographic Message Syntax (CMS) Key
           Package Receipt and Error Content Types", RFC 7191, April
           2014.

9.2. Informative References 🧚

[RFC5959]  Turner, S., "Algorithms for Asymmetric Key Package Content
           Type", RFC 5959, August 2010.

[RFC6033]  Turner, S., "Algorithms for Cryptographic Message Syntax
           (CMS) Encrypted Key Package Content Type", RFC 6033,
           December 2010.

[RFC6160]  Turner, S., "Algorithms for Cryptographic Message Syntax
           (CMS) Protection of Symmetric Key Package Content Types",
           RFC 6160, April 2011.

[RFC6161]  Turner, S., "Elliptic Curve Algorithms for Cryptographic
           Message Syntax (CMS) Encrypted Key Package Content Type",
           RFC 6161, April 2011.

[RFC6162]  Turner, S., "Elliptic Curve Algorithms for Cryptographic
           Message Syntax (CMS) Asymmetric Key Package Content Type",
           RFC 6162, April 2011.

[SP800-57] National Institute of Standards and Technology (NIST),
           Special Publication 800-57: Recommendation for Key
           Management - Part 1 (Revised), March 2007.

Author's Address 💖

Sean Turner IECA, Inc. 3057 Nutley Street, Suite 106 Fairfax, VA 22031 USA

EMail: turners@ieca.com

📦 where this page comes from

ietf: rfc7192 2014-04
💖 girlified by claude-haiku-5-5 on 2026-10-18: a language model's rewrite of the original, under its terms