Use of ML-KEM in the Cryptographic Message Syntax (CMS)
draft-ietf-lamps-cms-kyber-07

LAMPS                                                            J. Prat
Internet-Draft                                       CryptoNext Security
Intended status: Standards Track                            M. Ounsworth
Expires: 16 June 2025                                            Entrust
                                                            D. Van Geest
                                                     CryptoNext Security
                                                        13 December 2024

        Use of ML-KEM in the Cryptographic Message Syntax (CMS)
                     draft-ietf-lamps-cms-kyber-07

Abstract

   Module-Lattice-Based Key-Encapsulation Mechanism (ML-KEM) is a
   quantum-resistant key-encapsulation mechanism (KEM).  Three
   parameters sets for the ML-KEM algorithm are specified by NIST in
   FIPS 203.  In order of increasing security strength (and decreasing
   performance), these parameter sets are ML-KEM-512, ML-KEM-768, and
   ML-KEM-1024.  This document specifies the conventions for using ML-
   KEM with the Cryptographic Message Syntax (CMS) using the
   KEMRecipientInfo structure.

About This Document

   This note is to be removed before publishing as an RFC.

   Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-ietf-lamps-cms-kyber/.

   Discussion of this document takes place on the Limited Additional
   Mechanisms for PKIX and SMIME (lamps) Working Group mailing list
   (mailto:spasm@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/spasm/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/spasm/.

   Source for this draft and an issue tracker can be found at
   https://github.com/lamps-wg/cms-kyber.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions and Terminology . . . . . . . . . . . . . . .   3
     1.2.  ML-KEM  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Use of the ML-KEM Algorithm in CMS  . . . . . . . . . . . . .   4
     2.1.  RecipientInfo Conventions . . . . . . . . . . . . . . . .   4
     2.2.  Underlying Components . . . . . . . . . . . . . . . . . .   5
       2.2.1.  Use of the HKDF-based Key Derivation Function . . . .   5
       2.2.2.  Components for ML-KEM in CMS  . . . . . . . . . . . .   6
     2.3.  Certificate Conventions . . . . . . . . . . . . . . . . .   6
     2.4.  SMIME Capabilities Attribute Conventions  . . . . . . . .   7
   3.  Identifiers . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Appendix A.  ASN.1 Module . . . . . . . . . . . . . . . . . . . .  14
   Appendix B.  Security Strengths . . . . . . . . . . . . . . . . .  16
   Appendix C.  ML-KEM CMS Enveloped-Data Example  . . . . . . . . .  16
     C.1.  Originator CMS Processing . . . . . . . . . . . . . . . .  16
     C.2.  Recipient CMS Processing  . . . . . . . . . . . . . . . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

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1.  Introduction

   ML-KEM is an IND-CCA2-secure key-encapsulation mechanism (KEM)
   standardized in [FIPS203] by the US NIST PQC Project [NIST-PQ].
   Prior to standardization, the algorithm was known as Kyber.  ML-KEM
   and Kyber are not compatible.

   Native support for Key Encapsulation Mechanisms (KEMs) was added to
   CMS in [RFC9629], which defines the KEMRecipientInfo structure for
   the use of KEM algorithms for the CMS enveloped-data content type,
   the CMS authenticated-data content type, and the CMS authenticated-
   enveloped-data content type.  This document specifies the direct use
   of ML-KEM in the KEMRecipientInfo structure in CMS using each of the
   three parameter sets from [FIPS203], namely MK-KEM-512, ML-KEM-768,
   and ML-KEM-1024.  It does not address or preclude the use of ML-KEM
   as part of any hybrid scheme.

1.1.  Conventions and 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
   BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.2.  ML-KEM

   ML-KEM is a lattice-based key encapsulation mechanism using Module
   Learning with Errors as its underlying primitive, which is a
   structured lattices variant that offers good performance and
   relatively small and balanced key and ciphertext sizes.  ML-KEM was
   standardized with three parameter sets: ML-KEM-512, ML-KEM-768, and
   ML-KEM-1024.  The parameters for each of the security levels were
   chosen to be at least as secure as a generic block cipher of 128,
   192, or 256 bits, respectively.

   Like all KEM algorithms, ML-KEM provides three functions: KeyGen(),
   Encapsulate(), and Decapsulate().

   KeyGen() -> (pk, sk):  Generate the public key (pk) and a private key
      (sk).

   Encapsulate(pk) -> (ct, ss):  Given the recipient's public key (pk),
      produce a ciphertext (ct) to be passed to the recipient and a
      shared secret (ss) for use by the originator.

   Decapsulate(sk, ct) -> ss:  Given the private key (sk) and the
      ciphertext (ct), produce the shared secret (ss) for the recipient.

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   The KEM functions defined above correspond to the following functions
   in [FIPS203]:

   KeyGen():  ML-KEM.KeyGen() from section 7.1.

   Encapsulate():  ML-KEM.Encaps() from section 7.2.

   Decapsulate():  ML-KEM.Decaps() from section 7.3.

   All security levels of ML-KEM use SHA3-256, SHA3-512, SHAKE256, and
   SHAKE512 internally.

2.  Use of the ML-KEM Algorithm in CMS

   The ML-KEM algorithm MAY be employed for one or more recipients in
   the CMS enveloped-data content type [RFC5652], the CMS authenticated-
   data content type [RFC5652], or the CMS authenticated-enveloped-data
   content type [RFC5083].  In each case, the KEMRecipientInfo [RFC9629]
   is used with the ML-KEM algorithm to securely transfer the content-
   encryption key from the originator to the recipient.

   Processing ML-KEM with KEMRecipientInfo follows the same steps as
   Section 2 of [RFC9629].  To support the ML-KEM algorithm, a CMS
   originator MUST implement the Encapsulate() function and a CMS
   responder MUST implement the Decapsulate() function.

2.1.  RecipientInfo Conventions

   When the ML-KEM algorithm is employed for a recipient, the
   RecipientInfo alternative for that recipient MUST be
   OtherRecipientInfo using the KEMRecipientInfo structure as defined in
   [RFC9629].

   The fields of the KEMRecipientInfo MUST have the following values:

      version is the syntax version number; it MUST be 0.

      rid identifies the recipient's certificate or public key.

      kem identifies the KEM algorithm; it MUST contain one of id-alg-
      ml-kem-512, id-alg-ml-kem-768, or id-alg-ml-kem-1024.  These
      identifiers are reproduced in Section 3.

      kemct is the ciphertext produced for this recipient.

      kdf identifies the key-derivation algorithm.  Note that the Key
      Derivation Function (KDF) used for CMS RecipientInfo process MAY
      be different than the KDF used within the ML-KEM algorithm.

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      kekLength is the size of the key-encryption key in octets.

      ukm is an optional random input to the key-derivation function.
      ML-KEM doesn't place any requirements on the ukm contents.

      wrap identifies a key-encryption algorithm used to encrypt the
      content-encryption key.

2.2.  Underlying Components

   When ML-KEM is employed in CMS, the security levels of the different
   underlying components used within the KEMRecipientInfo structure
   SHOULD be consistent.

2.2.1.  Use of the HKDF-based Key Derivation Function

   The HMAC-based Extract-and-Expand Key Derivation Function (HKDF) is
   defined in [RFC5869].

   The HKDF function is a composition of the HKDF-Extract and HKDF-
   Expand functions.

   HKDF(salt, IKM, info, L)
     = HKDF-Expand(HKDF-Extract(salt, IKM), info, L)

   HKDF(salt, IKM, info, L) takes the following parameters:

   salt:  optional salt value (a non-secret random value).  In this
      document this parameter is unused, that is it is the zero-length
      string "".

   IKM:  input keying material.  In this document this is the shared
      secret outputted from the Encapsulate() or Decapsulate()
      functions.  This corresponds to the IKM KDF input from Section 5
      of [RFC9629].

   info:  optional context and application specific information.  In
      this document this corresponds to the info KDF input from
      Section 5 of [RFC9629].  This is the ASN.1 DER encoding of
      CMSORIforKEMOtherInfo.

   L:  length of output keying material in octets.  This corresponds to
      the L KDF input from Section 5 of [RFC9629], which is identified
      in the kekLength value from KEMRecipientInfo.  Implementations
      MUST confirm that this value is consistent with the key size of
      the key-encryption algorithm.

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   HKDF may be used with different hash functions, including SHA-256
   [FIPS180].  The object identifier id-alg-hkdf-with-sha256 is defined
   in [RFC8619], and specifies the use of HKDF with SHA-256.  The
   parameter field MUST be absent when this algorithm identifier is used
   to specify the KDF for ML-KEM in KemRecipientInfo.

2.2.2.  Components for ML-KEM in CMS

   A compliant implementation MUST support HKDF with SHA-256, using the
   id-alg-hkdf-with-sha256 KDF object identifier, as the
   KemRecipientInfo KDF for all ML-KEM parameter sets.  Note that the
   KDF used to process the KEMRecipientInfo structure MAY be different
   from the KDF used in the ML-KEM algorithm.

   For ML-KEM-512, an implementation must support the AES-Wrap-128
   [RFC3394] key-encryption algorithm using the id-aes128-wrap key-
   encryption algorithm object identifier [RFC3565].

   For ML-KEM-768 and ML-KEM-1024, an implementation must support the
   AES-Wrap-256 [RFC3394] key-encryption algorithm using the id-
   aes256-wrap key-encryption algorithm object identifier [RFC3565].

   The above object identifiers are reproduced for convenience in
   Section 3.

   An implementation MAY also support other key-derivation functions and
   other key-encryption algorithms.

   If underlying components other than those specified above are used,
   then the following KDF requirements are in effect in addition to
   those asserted in [RFC9629]:

      ML-KEM-512 SHOULD be used with a KDF capable of outputting a key
      with at least 128 bits of preimage strength and with a key
      wrapping algorithm with a key length of at least 128 bits.

      ML-KEM-768 SHOULD be used with a KDF capable of outputting a key
      with at least 192 bits of preimage strength and with a key
      wrapping algorithm with a key length of at least 192 bits.

      ML-KEM-1024 SHOULD be used with a KDF capable of outputting a key
      with at least 256 bits of preimage strength and with a key
      wrapping algorithm with a key length of at least 256 bits.

2.3.  Certificate Conventions

   The conventions specified in this section augment [RFC5280].

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   A recipient who employs the ML-KEM algorithm with a certificate MUST
   identify the public key in the certificate using the id-alg-ml-kem-
   512, id-alg-ml-kem-768, or id-alg-ml-kem-1024 object identifiers
   following the conventions specified in
   [I-D.ietf-lamps-kyber-certificates].

   In particular, the key usage certificate extension MUST only contain
   keyEncipherment (Section 4.2.1.3 of [RFC5280]).

2.4.  SMIME Capabilities Attribute Conventions

   Section 2.5.2 of [RFC8551] defines the SMIMECapabilities attribute to
   announce a partial list of algorithms that an S/MIME implementation
   can support.  When constructing a CMS signed-data content type
   [RFC5652], a compliant implementation MAY include the
   SMIMECapabilities attribute that announces support for one or more of
   the ML-KEM algorithm identifiers.

   The SMIMECapability SEQUENCE representing the ML-KEM algorithm MUST
   include one of the ML-KEM object identifiers in the capabilityID
   field.  When the one of the ML-KEM object identifiers appears in the
   capabilityID field, the parameters MUST NOT be present.

3.  Identifiers

   All identifiers used to indicate ML-KEM within CMS are defined
   elsewhere but reproduced here for convenience:

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     nistAlgorithms OBJECT IDENTIFIER ::= { joint-iso-ccitt(2)
         country(16) us(840) organization(1) gov(101) csor(3)
         nistAlgorithm(4) }
     kems OBJECT IDENTIFIER ::= { nistAlgorithms 4 }

     id-alg-ml-kem-512 OBJECT IDENTIFIER ::= { kems 1 }

     id-alg-ml-kem-768 OBJECT IDENTIFIER ::= { kems 2 }

     id-alg-ml-kem-1024 OBJECT IDENTIFIER ::= { kems 3 }

     hashAlgs OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16)
         us(840) organization(1) gov(101) csor(3) nistAlgorithm(4) 2 }

     id-alg-hkdf-with-sha256 OBJECT IDENTIFIER ::= { iso(1)
         member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
         smime(16) alg(3) 28 }

     aes OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
         organization(1) gov(101) csor(3) nistAlgorithms(4) 1 }

     id-aes128-wrap OBJECT IDENTIFIER ::= { aes 5 }
     id-aes256-wrap OBJECT IDENTIFIER ::= { aes 45 }

4.  Security Considerations

   The Security Considerations sections of
   [I-D.ietf-lamps-kyber-certificates] and [RFC9629] apply to this
   specification as well.

   For ML-KEM-specific security considerations refer to
   [I-D.sfluhrer-cfrg-ml-kem-security-considerations].

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   The ML-KEM variant and the underlying components need to be selected
   consistent with the desired security level.  Several security levels
   have been identified in NIST SP 800-57 Part 1 [NIST.SP.800-57pt1r5].
   To achieve 128-bit security, ML-KEM-512 SHOULD be used, the key-
   derivation function SHOULD provide at least 128 bits of preimage
   strength, and the symmetric key-encryption algorithm SHOULD have a
   security strength of at least 128 bits.  To achieve 192-bit security,
   ML-KEM-768 SHOULD be used, the key-derivation function SHOULD provide
   at least 192 bits of preimage strength, and the symmetric key-
   encryption algorithm SHOULD have a security strength of at least 192
   bits.  In the case of AES Key Wrap, a 256-bit key is typically used
   because AES-192 is not as commonly deployed.  To achieve 256-bit
   security, ML-KEM-1024 SHOULD be used, the key-derivation function
   SHOULD provide at least 256 bits of preimage strength, and the
   symmetric key-encryption algorithm SHOULD have a security strength of
   at least 256 bits.

   Provided all inputs are well-formed, the key establishment procedure
   of ML-KEM will never explicitly fail.  Specifically, the ML-
   KEM.Encaps and ML-KEM.Decaps algorithms from [FIPS203] will always
   output a value with the same data type as a shared secret key, and
   will never output an error or failure symbol for well-formed inputs.
   However, it is possible (though extremely unlikely) that the process
   will fail in the sense that ML-KEM.Encaps and ML-KEM.Decaps will
   produce different outputs, even though both of them are behaving
   honestly and no adversarial interference is present.  In this case,
   the sender and recipient clearly did not succeed in producing a
   shared secret key.  This event is called a decapsulation failure.
   Estimates for the decapsulation failure probability (or rate) for
   each of the ML-KEM parameter sets are provided in Table 1 of
   [FIPS203] and reproduced here in Table 1.

              +===============+============================+
              | Parameter set | Decapsulation failure rate |
              +===============+============================+
              | ML-KEM-512    | 2^(-138.8)                 |
              +---------------+----------------------------+
              | ML-KEM-768    | 2^(-164.8)                 |
              +---------------+----------------------------+
              | ML-KEM-1024   | 2^(-174.8)                 |
              +---------------+----------------------------+

               Table 1: ML-KEM decapsulation failure rates

   Implementations MUST protect the ML-KEM private key, the key-
   encryption key, the content-encryption key, message-authentication
   key, and the content-authenticated-encryption key.  Disclosure of the
   ML-KEM private key could result in the compromise of all messages

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   protected with that key.  Disclosure of the key-encryption key, the
   content-encryption key, or the content-authenticated-encryption key
   could result in compromise of the associated encrypted content.
   Disclosure of the key-encryption key, the message-authentication key,
   or the content-authenticated-encryption key could allow modification
   of the associated authenticated content.

   Additional considerations related to key management may be found in
   [NIST.SP.800-57pt1r5].

   The security of the ML-KEM algorithm depends on a quality random
   number generator.  For further discussion on random number
   generation, see [RFC4086].

   ML-KEM encapsulation and decapsulation only outputs a shared secret
   and ciphertext.  Implementations SHOULD NOT use intermediate values
   directly for any purpose.

   Implementations SHOULD NOT reveal information about intermediate
   values or calculations, whether by timing or other "side channels",
   otherwise an opponent may be able to determine information about the
   keying data and/or the recipient's private key.  Although not all
   intermediate information may be useful to an opponent, it is
   preferable to conceal as much information as is practical, unless
   analysis specifically indicates that the information would not be
   useful to an opponent.

   Generally, good cryptographic practice employs a given ML-KEM key
   pair in only one scheme.  This practice avoids the risk that
   vulnerability in one scheme may compromise the security of the other,
   and may be essential to maintain provable security.

   Parties MAY gain assurance that implementations are correct through
   formal implementation validation, such as the NIST Cryptographic
   Module Validation Program (CMVP) [CMVP].

5.  IANA Considerations

   For the ASN.1 Module in Appendix A, IANA is requested to assign an
   object identifier (OID) for the module identifier (TBD1) with a
   Description of "id-mod-cms-ml-kem-2024".  The OID for the module
   should be allocated in the "SMI Security for S/MIME Module
   Identifier" registry (1.2.840.113549.1.9.16.0).

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6.  Acknowledgements

   This document borrows heavily from [I-D.ietf-lamps-rfc5990bis],
   [FIPS203], and [I-D.kampanakis-ml-kem-ikev2].  Thanks go to the
   authors of those documents.  "Copying always makes things easier and
   less error prone" - RFC8411.

   Thanks to Carl Wallace, Jonathan Hammel, and Sean Turner for the
   detailed review and Carl Wallace for interoperability testing.

7.  References

7.1.  Normative References

   [FIPS203]  "Module-lattice-based key-encapsulation mechanism
              standard", National Institute of Standards and Technology
              (U.S.), DOI 10.6028/nist.fips.203, August 2024,
              <https://doi.org/10.6028/nist.fips.203>.

   [I-D.ietf-lamps-kyber-certificates]
              Turner, S., Kampanakis, P., Massimo, J., and B.
              Westerbaan, "Internet X.509 Public Key Infrastructure -
              Algorithm Identifiers for the Module-Lattice-Based Key-
              Encapsulation Mechanism (ML-KEM)", Work in Progress,
              Internet-Draft, draft-ietf-lamps-kyber-certificates-06, 4
              November 2024, <https://datatracker.ietf.org/doc/html/
              draft-ietf-lamps-kyber-certificates-06>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC3394]  Schaad, J. and R. Housley, "Advanced Encryption Standard
              (AES) Key Wrap Algorithm", RFC 3394, DOI 10.17487/RFC3394,
              September 2002, <https://www.rfc-editor.org/rfc/rfc3394>.

   [RFC3565]  Schaad, J., "Use of the Advanced Encryption Standard (AES)
              Encryption Algorithm in Cryptographic Message Syntax
              (CMS)", RFC 3565, DOI 10.17487/RFC3565, July 2003,
              <https://www.rfc-editor.org/rfc/rfc3565>.

   [RFC5083]  Housley, R., "Cryptographic Message Syntax (CMS)
              Authenticated-Enveloped-Data Content Type", RFC 5083,
              DOI 10.17487/RFC5083, November 2007,
              <https://www.rfc-editor.org/rfc/rfc5083>.

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   [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, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/rfc/rfc5280>.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, DOI 10.17487/RFC5652, September 2009,
              <https://www.rfc-editor.org/rfc/rfc5652>.

   [RFC5869]  Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
              Key Derivation Function (HKDF)", RFC 5869,
              DOI 10.17487/RFC5869, May 2010,
              <https://www.rfc-editor.org/rfc/rfc5869>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC8551]  Schaad, J., Ramsdell, B., and S. Turner, "Secure/
              Multipurpose Internet Mail Extensions (S/MIME) Version 4.0
              Message Specification", RFC 8551, DOI 10.17487/RFC8551,
              April 2019, <https://www.rfc-editor.org/rfc/rfc8551>.

   [RFC8619]  Housley, R., "Algorithm Identifiers for the HMAC-based
              Extract-and-Expand Key Derivation Function (HKDF)",
              RFC 8619, DOI 10.17487/RFC8619, June 2019,
              <https://www.rfc-editor.org/rfc/rfc8619>.

   [RFC9629]  Housley, R., Gray, J., and T. Okubo, "Using Key
              Encapsulation Mechanism (KEM) Algorithms in the
              Cryptographic Message Syntax (CMS)", RFC 9629,
              DOI 10.17487/RFC9629, August 2024,
              <https://www.rfc-editor.org/rfc/rfc9629>.

   [X680]     ITU-T, "Information technology - Abstract Syntax Notation
              One (ASN.1): Specification of basic notation", ITU-T
              Recommendation X.680, ISO/IEC 8824-1:2021, February 2021,
              <https://www.itu.int/rec/T-REC-X.680>.

7.2.  Informative References

   [CMVP]     National Institute of Standards and Technology,
              "Cryptographic Module Validation Program", 2016,
              <https://csrc.nist.gov/projects/cryptographic-module-
              validation-program>.

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   [FIPS180]  Dang, Q. H. and NIST, "Secure Hash Standard", NIST Federal
              Information Processing Standards Publications 180-4,
              DOI 10.6028/NIST.FIPS.180-4, July 2015,
              <https://nvlpubs.nist.gov/nistpubs/FIPS/
              NIST.FIPS.180-4.pdf>.

   [I-D.ietf-lamps-rfc5990bis]
              Housley, R. and S. Turner, "Use of the RSA-KEM Algorithm
              in the Cryptographic Message Syntax (CMS)", Work in
              Progress, Internet-Draft, draft-ietf-lamps-rfc5990bis-10,
              30 July 2024, <https://datatracker.ietf.org/doc/html/
              draft-ietf-lamps-rfc5990bis-10>.

   [I-D.kampanakis-ml-kem-ikev2]
              Kampanakis, P. and G. Ravago, "Post-quantum Hybrid Key
              Exchange with ML-KEM in the Internet Key Exchange Protocol
              Version 2 (IKEv2)", Work in Progress, Internet-Draft,
              draft-kampanakis-ml-kem-ikev2-09, 4 November 2024,
              <https://datatracker.ietf.org/doc/html/draft-kampanakis-
              ml-kem-ikev2-09>.

   [I-D.sfluhrer-cfrg-ml-kem-security-considerations]
              Fluhrer, S., Dang, Q., Mattsson, J. P., Milner, K., and D.
              Shiu, "ML-KEM Security Considerations", Work in Progress,
              Internet-Draft, draft-sfluhrer-cfrg-ml-kem-security-
              considerations-02, 19 November 2024,
              <https://datatracker.ietf.org/doc/html/draft-sfluhrer-
              cfrg-ml-kem-security-considerations-02>.

   [NIST-PQ]  National Institute of Standards and Technology, "Post-
              Quantum Cryptography Project", 20 December 2016,
              <https://csrc.nist.gov/projects/post-quantum-
              cryptography>.

   [NIST.SP.800-57pt1r5]
              Barker, E. and NIST, "Recommendation for key
              management:part 1 - general", NIST Special Publications
              (General) 800-57pt1r5, DOI 10.6028/NIST.SP.800-57pt1r5,
              May 2020,
              <https://nvlpubs.nist.gov/nistpubs/SpecialPublications/
              NIST.SP.800-57pt1r5.pdf>.

   [RFC4086]  Eastlake 3rd, D., Schiller, J., and S. Crocker,
              "Randomness Requirements for Security", BCP 106, RFC 4086,
              DOI 10.17487/RFC4086, June 2005,
              <https://www.rfc-editor.org/rfc/rfc4086>.

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   [RFC5911]  Hoffman, P. and J. Schaad, "New ASN.1 Modules for
              Cryptographic Message Syntax (CMS) and S/MIME", RFC 5911,
              DOI 10.17487/RFC5911, June 2010,
              <https://www.rfc-editor.org/rfc/rfc5911>.

Appendix A.  ASN.1 Module

   This appendix includes the ASN.1 module [X680] for ML-KEM.  This
   module imports objects from [RFC5911], [RFC9629], [RFC8619],
   [I-D.ietf-lamps-kyber-certificates].

   RFC EDITOR: Please replace TBD2 with the value assigned by IANA
   during the publication of [I-D.ietf-lamps-kyber-certificates].  Also
   please replace [I-D.ietf-lamps-kyber-certificates] in the module with
   a reference to the published RFC.

   <CODE BEGINS>
   CMS-ML-KEM-2024
   { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
     pkcs-9(9) smime(16) modules(0) id-mod-cms-ml-kem-2024(TBD1) }

   DEFINITIONS IMPLICIT TAGS ::= BEGIN

   EXPORTS ALL;

   IMPORTS
     SMIME-CAPS
       FROM AlgorithmInformation-2009  -- [RFC5911]
         { iso(1) identified-organization(3) dod(6) internet(1)
           security(5) mechanisms(5) pkix(7) id-mod(0)
           id-mod-algorithmInformation-02(58) }

     KEM-ALGORITHM
       FROM KEMAlgorithmInformation-2023  -- [RFC9629]
          { iso(1) identified-organization(3) dod(6) internet(1)
            security(5) mechanisms(5) pkix(7) id-mod(0)
            id-mod-kemAlgorithmInformation-2023(109) }

     kda-hkdf-with-sha256
       FROM HKDF-OID-2019  -- [RFC8619]
          { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
            pkcs-9(9) smime(16) modules(0) id-mod-hkdf-oid-2019(68) }

     kwa-aes128-wrap, kwa-aes256-wrap
       FROM CMSAesRsaesOaep-2009  -- [RFC5911]
          { iso(1) member-body(2) us(840) rsadsi(113549)
          pkcs(1) pkcs-9(9) smime(16) modules(0)
          id-mod-cms-aes-02(38) }

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     id-alg-ml-kem-512, id-alg-ml-kem-768, id-alg-ml-kem-1024,
     pk-ml-kem-512, pk-ml-kem-768, pk-ml-kem-1024
       FROM X509-ML-KEM-2024 -- [I-D.ietf-lamps-kyber-certificates]
          { iso(1) identified-organization(3) dod(6)
            internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
            id-mod-x509-ml-kem-2024(TBD2) };

   --
   -- ML-KEM Key Encapsulation Mechanism Algorithms
   --

   kema-ml-kem-512 KEM-ALGORITHM ::= {
      IDENTIFIER id-alg-ml-kem-512
      PARAMS ARE absent
      PUBLIC-KEYS { pk-ml-kem-512 }
      UKM ARE optional
      SMIME-CAPS { IDENTIFIED BY id-alg-ml-kem-512 } }

   kema-ml-kem-768 KEM-ALGORITHM ::= {
      IDENTIFIER id-alg-ml-kem-768
      PARAMS ARE absent
      PUBLIC-KEYS { pk-ml-kem-768 }
      UKM ARE optional
      SMIME-CAPS { IDENTIFIED BY id-alg-ml-kem-768 } }

   kema-ml-kem-1024 KEM-ALGORITHM ::= {
      IDENTIFIER id-alg-ml-kem-1024
      PARAMS ARE absent
      PUBLIC-KEYS { pk-ml-kem-1024 }
      UKM ARE optional
      SMIME-CAPS { IDENTIFIED BY id-alg-ml-kem-1024 } }

   -- Updates for the SMIME-CAPS Set from RFC 5911

   SMimeCapsSet SMIME-CAPS ::=
      { kema-ml-kem-512.&smimeCaps |
        kema-ml-kem-768.&smimeCaps |
        kema-ml-kem-1024.&smimeCaps |
        kda-hkdf-with-sha256.&smimeCaps |
        kwa-aes128-wrap.&smimeCaps |
        kwa-aes256-wrap.&smimeCaps,
        ... }

   END
   <CODE ENDS>

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Appendix B.  Security Strengths

   Instead of defining the strength of a quantum algorithm in a
   traditional manner using the imprecise notion of bits of security,
   NIST has defined security levels by picking a reference scheme, which
   NIST expects to offer notable levels of resistance to both quantum
   and classical attack.  To wit, a KEM algorithm that achieves NIST PQC
   security must require computational resources to break IND-CCA2
   security comparable or greater than that required for key search on
   AES-128, AES-192, and AES-256 for Levels 1, 3, and 5, respectively.
   Levels 2 and 4 use collision search for SHA-256 and SHA-384 as
   reference.

     +=======+===============+========+========+============+========+
     | Level | Parameter Set | Encap. | Decap. | Ciphertext | Secret |
     |       |               | Key    | Key    |            |        |
     +=======+===============+========+========+============+========+
     | 1     | ML-KEM-512    | 800    | 1632   | 768        | 32     |
     +-------+---------------+--------+--------+------------+--------+
     | 3     | ML-KEM-768    | 1184   | 2400   | 1952       | 32     |
     +-------+---------------+--------+--------+------------+--------+
     | 5     | ML-KEM-1024   | 1568   | 3168   | 2592       | 32     |
     +-------+---------------+--------+--------+------------+--------+

                Table 2: ML-KEM security strengths and sized

Appendix C.  ML-KEM CMS Enveloped-Data Example

   This example shows the establishment of an AES-128 content-encryption
   key using:

   *  ML-DSA-512 and HKDF with SHA-256;

   *  KEMRecipientInfo key derivation using HKDF with SHA-256; and

   *  KEMRecipientInfo key wrap using AES-128-KEYWRAP.

   In real-world use, the originator would encrypt the content-
   encryption key in a manner that would allow decryption with their own
   private key as well as the recipient's private key.  This is omitted
   in an attempt to simplify the example.

C.1.  Originator CMS Processing

   Alice obtains Bob's ML-KEM-512 public key:

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   -----BEGIN PUBLIC KEY-----
   MIIDMjALBglghkgBZQMEBAEDggMhADmVgV5ZfRBDVc8pqlMzyTJRhp1bzb5IcST2
   Ari2pmwWxHYWSK12XPXYAGtRXpBafwrAdrDGLvoygVPnylcBaZ8TBfHmvG+QsOSb
   aTUSts6ZKouAFt38GmYsfj+WGcvYad13GvMIlszVkYrGy3dGbF53mZbWf/mqvJdQ
   Pyx7fi0ADYZFD7GAfKTKvaRlgloxx4mht6SRqzhydl0yDQtxkg+iE8lAk0Frg7gS
   Tmn2XmLLUADcw3qpoP/3OXDEdy81fSQYnKb1MFVowOI3ajdipoxgXlY8XSCVcuD8
   dTLKKUcpU1VntfxBPF6HktJGRTbMgI+YrddGZPFBVm+QFqkKVBgpqYoEZM5BqLtE
   wtT6PCwglGByjvFKGnxMm5jRIgO0zDUpFgqasteDj3/2tTrgWqMafWRrevpsRZMl
   JqPDdVYZvplMIRwqMcBbNEeDbLIVC+GCna5rBMVTXP9Ubjkrp5dBFyD5JPSQpaxU
   lfITVtVQt4KmTBaItrZVvMeEIZekNML2Vjtbfwmni8xIgjJ4NWHRb0y6tnVUAAUH
   gVcMZmBLgXrRJSKUc26LAYYaS1p0UZuLb+UUiaUHI5Llh2JscTd2V10zgGocjicy
   r5fCaA9RZmMxxOuLvAQxxPloMtrxs8RVKPuhU/bHixwZhwKUfM0zdyekb7U7oR3l
   y0GRNGhZUWy2rXJADzzyCbI2rvNaWArIfrPjD6/WaXPKin3SZ1r0H3oXthQzzRr4
   D3cIhp9mVIhJeYCxrBCgzctjagDthoGzXkKRJMqANQcluF+DperDpKPMFgCQPmUp
   NWC5szblrw1SnawaBIEZMCy3qbzBELlIUb8CEX8ZncSFqFK3Rz8JuDGmgx1bVMC3
   kNIlz2u5LZRiomzbM92lEjx6rw4moLg2Ve6ii/OoB0clAY/WuuS2Ac9huqtxp6PT
   UZejQ+dLSicsEl1UCJZCbYW3lY07OKa6mH7DciXHtEzbEt3kU5tKsII2NoPwS/eg
   nMXEHf6DChsWLgsyQzQ2LwhKFEZ3IzRLrdAA+NjFN8SPmY8FMHzr0e3guBw7xZoG
   WhttY7Js
   -----END PUBLIC KEY-----

   Bob's ML-KEM-512 public key has the following key identifier:

   599788C37AED400EE405D1B2A3366AB17D824A51

   Alice generates a shared secret and ciphertext using Bob's ML-KEM-512
   public key, derives the key-encryption key from the shared secret and
   CMSORIforKEMOtherInfo using HKDF with SHA-256, randomly generates a
   128-bit content-encryption key, uses AES-128-KEYWRAP to encrypt the
   content-encryption key with the key-encryption key, encrypts the
   plaintext content with the content-encryption key and encodes the
   EnvelopedData (using KEMRecipientInfo) and ContentInfo, and then
   sends the result to Bob.

   The Base64-encoded result is:

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   -----BEGIN CMS-----
   MIID8gYLKoZIhvcNAQkQARegggPhMIID3QIBADGCA4ikggOEBgsqhkiG9w0BCRAN
   AzCCA3MCAQCAFFmXiMN67UAO5AXRsqM2arF9gkpRMAsGCWCGSAFlAwQEAQSCAwDz
   6kG2NhIUhlAHMA3HCeC8G9o0Ey8HMa//d2N7a7e92ba+Xrwfp9NKfiwH3r26CvqG
   Aj5LgU/hbzNkFGw1AfgXDQTcpHEjfPB2R/x6OxiuV6KPxOjqHbjDvyRoclHHrGfG
   i4uBkgPSAXrBlzXop9n7F4sxae2grAJIWX8sl/Vs6BRcKmuAIXbriZTQnEoojgyr
   ncDz3owBMBdLvA7STNEJ9vt3WaGV07/3qjSCHsxynDwWpiHYwf3Q++/VlZNrPnzZ
   B/ulQtAWweHxgTpvX0k8WnCKSl9S5qGIMK2Tc4KBMSqb02pkSMDV/YEKCwPyFgIO
   hEleCys+umJmUAbGm0cmH0Kev0sHAnYvg02uebvK2xFW6uboTy0Txj8okoy5sP6h
   mRekF6qgrEEa3/CjkSAxW9iv986h64UUU0cWZeEaEl0eYR6LOf3e16ZPSYDC8Xo7
   VjAZvYuf8QuLlqDCw73Rp+PT+fkFqfY4dxGXwZYMU/UOuQqi2IsT86W8gmsQPhEv
   7EvSScX8TJSDsrQOVrGoHc5OymRmuepkn17ORYyrR8iKEDVJEDCGesJbgcCoi2VT
   LFdDYOzMn1T6gSsmyg3KGWLqdn8csG/mPjKblyBmlYbM8KT4ICqQx1nBngGUfMIV
   +v4wY9s0vcLSTBI5QCbgPRrIzz0B97sZdcp29uXA4Qlz2riuRpn38up1G90BGxvo
   lukVQ8djNhhGgC60UJwA3bRn+O2xo/cSBkMSLJIIqA5QSY+zcPu90MqvN1JFkbO6
   YJQbtuFvQ9hAmHJNrWRaXRGLJuH8gxUhG2bhOn5jjtgmVdKHx8gFDxHs13IQMHAU
   //u5JHvJOnC8HLWPIbMTXa0giC7H22Gf7GMdYVG0pNr37wEJkfd7D4OKM5S0fXH3
   4moC701Bgypt0D+inpqd+Vdyzylg5KkkoLcQqiE1tAPYc2FCSJNhZe/xA4/WOkoO
   HS6/FvFcNaIxkwmNDl9BM4J+Zv4zxqcrqjSUuRM9r/IepBU22+EltUGXug15v+Mw
   DQYLKoZIhvcNAQkQAxwCASAwCwYJYIZIAWUDBAEtBCgSWjJGbANW6249qJezunw8
   TekPnqeXQxQsCApolNdBREvHJzVFD8fxMDoGCSqGSIb3DQEHATAeBglghkgBZQME
   AS4wEQQM09P1v4RTaKUfxd6/AgEQgA0W/2sAf/+wpWYbxab8BBAcFxeZJbrC7Ifl
   jQHB7vah
   -----END CMS-----

   This result decodes to:

      0 1010: SEQUENCE {
      4   11:  OBJECT IDENTIFIER
            :   authEnvelopedData (1 2 840 113549 1 9 16 1 23)
     17  993:  [0] {
     21  989:   SEQUENCE {
     25    1:    INTEGER 0
     28  904:    SET {
     32  900:     [4] {
     36   11:      OBJECT IDENTIFIER '1 2 840 113549 1 9 16 13 3'
     49  883:      SEQUENCE {
     53    1:       INTEGER 0
     56   20:       [0]
            :    59 97 88 C3 7A ED 40 0E E4 05 D1 B2 A3 36 6A B1
            :    7D 82 4A 51
     78   11:       SEQUENCE {
     80    9:        OBJECT IDENTIFIER '2 16 840 1 101 3 4 4 1'
            :         }
     91  768:       OCTET STRING
            :    F3 EA 41 B6 36 12 14 86 50 07 30 0D C7 09 E0 BC
            :    1B DA 34 13 2F 07 31 AF FF 77 63 7B 6B B7 BD D9
            :    B6 BE 5E BC 1F A7 D3 4A 7E 2C 07 DE BD BA 0A FA

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            :    86 02 3E 4B 81 4F E1 6F 33 64 14 6C 35 01 F8 17
            :    0D 04 DC A4 71 23 7C F0 76 47 FC 7A 3B 18 AE 57
            :    A2 8F C4 E8 EA 1D B8 C3 BF 24 68 72 51 C7 AC 67
            :    C6 8B 8B 81 92 03 D2 01 7A C1 97 35 E8 A7 D9 FB
            :    17 8B 31 69 ED A0 AC 02 48 59 7F 2C 97 F5 6C E8
            :    14 5C 2A 6B 80 21 76 EB 89 94 D0 9C 4A 28 8E 0C
            :    AB 9D C0 F3 DE 8C 01 30 17 4B BC 0E D2 4C D1 09
            :    F6 FB 77 59 A1 95 D3 BF F7 AA 34 82 1E CC 72 9C
            :    3C 16 A6 21 D8 C1 FD D0 FB EF D5 95 93 6B 3E 7C
            :    D9 07 FB A5 42 D0 16 C1 E1 F1 81 3A 6F 5F 49 3C
            :    5A 70 8A 4A 5F 52 E6 A1 88 30 AD 93 73 82 81 31
            :    2A 9B D3 6A 64 48 C0 D5 FD 81 0A 0B 03 F2 16 02
            :    0E 84 49 5E 0B 2B 3E BA 62 66 50 06 C6 9B 47 26
            :    1F 42 9E BF 4B 07 02 76 2F 83 4D AE 79 BB CA DB
            :    11 56 EA E6 E8 4F 2D 13 C6 3F 28 92 8C B9 B0 FE
            :    A1 99 17 A4 17 AA A0 AC 41 1A DF F0 A3 91 20 31
            :    5B D8 AF F7 CE A1 EB 85 14 53 47 16 65 E1 1A 12
            :    5D 1E 61 1E 8B 39 FD DE D7 A6 4F 49 80 C2 F1 7A
            :    3B 56 30 19 BD 8B 9F F1 0B 8B 96 A0 C2 C3 BD D1
            :    A7 E3 D3 F9 F9 05 A9 F6 38 77 11 97 C1 96 0C 53
            :    F5 0E B9 0A A2 D8 8B 13 F3 A5 BC 82 6B 10 3E 11
            :    2F EC 4B D2 49 C5 FC 4C 94 83 B2 B4 0E 56 B1 A8
            :    1D CE 4E CA 64 66 B9 EA 64 9F 5E CE 45 8C AB 47
            :    C8 8A 10 35 49 10 30 86 7A C2 5B 81 C0 A8 8B 65
            :    53 2C 57 43 60 EC CC 9F 54 FA 81 2B 26 CA 0D CA
            :    19 62 EA 76 7F 1C B0 6F E6 3E 32 9B 97 20 66 95
            :    86 CC F0 A4 F8 20 2A 90 C7 59 C1 9E 01 94 7C C2
            :    15 FA FE 30 63 DB 34 BD C2 D2 4C 12 39 40 26 E0
            :    3D 1A C8 CF 3D 01 F7 BB 19 75 CA 76 F6 E5 C0 E1
            :    09 73 DA B8 AE 46 99 F7 F2 EA 75 1B DD 01 1B 1B
            :    E8 96 E9 15 43 C7 63 36 18 46 80 2E B4 50 9C 00
            :    DD B4 67 F8 ED B1 A3 F7 12 06 43 12 2C 92 08 A8
            :    0E 50 49 8F B3 70 FB BD D0 CA AF 37 52 45 91 B3
            :    BA 60 94 1B B6 E1 6F 43 D8 40 98 72 4D AD 64 5A
            :    5D 11 8B 26 E1 FC 83 15 21 1B 66 E1 3A 7E 63 8E
            :    D8 26 55 D2 87 C7 C8 05 0F 11 EC D7 72 10 30 70
            :    14 FF FB B9 24 7B C9 3A 70 BC 1C B5 8F 21 B3 13
            :    5D AD 20 88 2E C7 DB 61 9F EC 63 1D 61 51 B4 A4
            :    DA F7 EF 01 09 91 F7 7B 0F 83 8A 33 94 B4 7D 71
            :    F7 E2 6A 02 EF 4D 41 83 2A 6D D0 3F A2 9E 9A 9D
            :    F9 57 72 CF 29 60 E4 A9 24 A0 B7 10 AA 21 35 B4
            :    03 D8 73 61 42 48 93 61 65 EF F1 03 8F D6 3A 4A
            :    0E 1D 2E BF 16 F1 5C 35 A2 31 93 09 8D 0E 5F 41
            :    33 82 7E 66 FE 33 C6 A7 2B AA 34 94 B9 13 3D AF
            :    F2 1E A4 15 36 DB E1 25 B5 41 97 BA 0D 79 BF E3
    863   13:       SEQUENCE {
    865   11:        OBJECT IDENTIFIER
            :         hkdfWithSha256 (1 2 840 113549 1 9 16 3 28)

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            :         }
    878    1:       INTEGER 32
    881   11:       SEQUENCE {
    883    9:        OBJECT IDENTIFIER
            :         aes256-wrap (2 16 840 1 101 3 4 1 45)
            :         }
    894   40:       OCTET STRING
            :    12 5A 32 46 6C 03 56 EB 6E 3D A8 97 B3 BA 7C 3C
            :    4D E9 0F 9E A7 97 43 14 2C 08 0A 68 94 D7 41 44
            :    4B C7 27 35 45 0F C7 F1
            :        }
            :       }
            :      }
    936   58:    SEQUENCE {
    938    9:     OBJECT IDENTIFIER data (1 2 840 113549 1 7 1)
    949   30:     SEQUENCE {
    951    9:      OBJECT IDENTIFIER
            :       aes256-GCM (2 16 840 1 101 3 4 1 46)
    962   17:      SEQUENCE {
    964   12:       OCTET STRING D3 D3 F5 BF 84 53 68 A5 1F C5 DE BF
    978    1:       INTEGER 16
            :        }
            :       }
    981   13:     [0] 16 FF 6B 00 7F FF B0 A5 66 1B C5 A6 FC
            :      }
    996   16:    OCTET STRING
            :    1C 17 17 99 25 BA C2 EC 87 E5 8D 01 C1 EE F6 A1
            :     }
            :    }
            :   }

C.2.  Recipient CMS Processing

   Bob's ML-KEM-512 private key:

   -----BEGIN PRIVATE KEY-----
   MFICAQAwCwYJYIZIAWUDBAQBBEAAAQIDBAUGBwgJCgsMDQ4PEBESExQVFhcYGRob
   HB0eHyAhIiMkJSYnKCkqKywtLi8wMTIzNDU2Nzg5Ojs8PT4/
   -----END PRIVATE KEY-----

   Bob decapsulates the ciphertext in the KEMRecipientInfo to get the
   ML-KEM-512 shared secret, derives the key-encryption key from the
   shared secret and CMSORIforKEMOtherInfo using HKDF with SHA-256, uses
   AES-128-KEYWRAP to decrypt the content-encryption key with the key-
   encryption key, and decrypts the encrypted contents with the content-
   encryption key, revealing the plaintext content:

   Hello, world!

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Authors' Addresses

   Julien Prat
   CryptoNext Security
   16, Boulevard Saint-Germain
   75005 Paris
   France
   Email: julien.prat@cryptonext-security.com

   Mike Ounsworth
   Entrust Limited
   2500 Solandt Road -- Suite 100
   Ottawa, Ontario  K2K 3G5
   Canada
   Email: mike.ounsworth@entrust.com

   Daniel Van Geest
   CryptoNext Security
   16, Boulevard Saint-Germain
   75005 Paris
   France
   Email: daniel.vangeest@cryptonext-security.com

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