Skip to main content

Use of the FN-DSA Signature Algorithm in the Cryptographic Message Syntax (CMS)
draft-turner-lamps-cms-fn-dsa-00

Document Type Active Internet-Draft (individual)
Authors Daniel Van Geest , Sean Turner
Last updated 2025-11-04
RFC stream (None)
Intended RFC status (None)
Formats
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-turner-lamps-cms-fn-dsa-00
Limited Additional Mechanisms for PKIX and SMIME            D. Van Geest
Internet-Draft                                       CryptoNext Security
Intended status: Standards Track                               S. Turner
Expires: 8 May 2026                                                sn3rd
                                                         4 November 2025

   Use of the FN-DSA Signature Algorithm in the Cryptographic Message
                              Syntax (CMS)
                    draft-turner-lamps-cms-fn-dsa-00

Abstract

   The Fast-Fourier Transform over NTRU-Lattice-Based Digital Signature
   Algorithm (FN-DSA), as defined by NIST in FIPS 206, is a post-quantum
   digital signature scheme that aims to be secure against an adversary
   in possession of a Cryptographically Relevant Quantum Computer
   (CRQC).  This document specifies the conventions for using the FN-DSA
   signature algorithm with the Cryptographic Message Syntax (CMS).  In
   addition, the algorithm identifier is provided.

About This Document

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

   The latest revision of this draft can be found at
   https://seanturner.github.io/cms-fn-dsa/draft-turner-lamps-cms-fn-
   dsa.html.  Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-turner-lamps-cms-fn-dsa/.

   Discussion of this document takes place on the Limited Additional
   Mechanisms for PKIX and SMIME 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/seanturner/cms-fn-dsa.

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/.

Van Geest & Turner         Expires 8 May 2026                   [Page 1]
Internet-Draft              FN-DSA in the CMS              November 2025

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 8 May 2026.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions and Definitions . . . . . . . . . . . . . . .   3
   2.  FN-DSA Algorithm Identifiers  . . . . . . . . . . . . . . . .   3
   3.  Signed-Data Conventions . . . . . . . . . . . . . . . . . . .   4
     3.1.  Pure Mode vs Pre-hash Mode  . . . . . . . . . . . . . . .   4
     3.2.  Signature Generation and Verification . . . . . . . . . .   5
     3.3.  SignerInfo Content  . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   5.  Operational Considerations  . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A.  ASN.1 Module . . . . . . . . . . . . . . . . . . . .  11
   Appendix B.  Examples . . . . . . . . . . . . . . . . . . . . . .  12
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

Van Geest & Turner         Expires 8 May 2026                   [Page 2]
Internet-Draft              FN-DSA in the CMS              November 2025

1.  Introduction

   The Fast-Fourier Transform over NTRU-Lattice-Based Digital Signature
   Algorithm (FN-DSA) is a digital signature algorithm standardised by
   the US National Institute of Standards and Technology (NIST) as part
   of their post-quantum cryptography standardisation process.  It is
   intended to be secure against both "traditional" cryptographic
   attacks, as well as attacks utilising a quantum computer.  It offers
   smaller signatures and significantly faster runtimes than SLH-DSA
   [FIPS205], an alternative post-quantum signature algorithm also
   standardised by NIST.  This document specifies the use of the FN-DSA
   in the CMS at two security levels: FN-DSA-512 and FN-DSA-1024.  See
   Appendix B of I-D.turner-lamps-fn-dsa-certificates for more
   information on the security levels and key sizes of FN-DSA.

   Prior to standardisation, FN-DSA was known as Falcon.  FN-DSA and
   Falcon are not compatible.

   For each of the FN-DSA parameter sets, an algorithm identifier Object
   Identifier (OID) has been specified.

1.1.  Conventions and Definitions

   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
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  FN-DSA Algorithm Identifiers

   Many ASN.1 data structure types use the AlgorithmIdentifier type to
   identify cryptographic algorithms.  In the CMS, the
   AlgorithmIdentifier field is used to identify FN-DSA signatures in
   the signed-data content type.  They may also appear in X.509
   certificates used to verify those signatures.  The same
   AlgorithmIdentifier values are used to identify FN-DSA public keys
   and signature algorithms.  I-D.turner-lamps-fn-dsa-certificates
   describes the use of FN-DSA in X.509 certificates.  The
   AlgorithmIdentifier type is defined as follows:

   AlgorithmIdentifier{ALGORITHM-TYPE, ALGORITHM-TYPE:AlgorithmSet} ::=
           SEQUENCE {
               algorithm   ALGORITHM-TYPE.&id({AlgorithmSet}),
               parameters  ALGORITHM-TYPE.
                      &Params({AlgorithmSet}{@algorithm}) OPTIONAL
           }

Van Geest & Turner         Expires 8 May 2026                   [Page 3]
Internet-Draft              FN-DSA in the CMS              November 2025

      |  NOTE: The above syntax is from [RFC5911] and is compatible with
      |  the 2021 ASN.1 syntax [X680].  See [RFC5280] for the 1988 ASN.1
      |  syntax.

   The fields in the AlgorithmIdentifier type have the following
   meanings:

   algorithm:  The algorithm field contains an OID that identifies the
      cryptographic algorithm in use.  The OIDs for FN-DSA are described
      below.

   parameters:  The parameters field contains parameter information for
      the algorithm identified by the OID in the algorithm field.  Each
      FN-DSA parameter set is identified by its own algorithm OID, so
      there is no relevant information to include in this field.  As
      such, parameters MUST be omitted when encoding an FN-DSA
      AlgorithmIdentifier.

   The OIDs for FN-DSA are defined in the NIST Computer Security Objects
   Register [CSOR], and are reproduced here for convenience.

      |  TODO: NIST WILL ASSIGN THESE.

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

   id-fn-dsa-512 OBJECT IDENTIFIER ::= { sigAlgs TBD }

   id-fn-dsa-1024 OBJECT IDENTIFIER ::= { sigAlgs TBD }

3.  Signed-Data Conventions

3.1.  Pure Mode vs Pre-hash Mode

   [RFC5652] specifies that digital signatures for CMS are produced
   using a digest of the message to be signed and the signer's private
   key.  At the time of publication of that RFC, all signature
   algorithms supported in the CMS required a message digest to be
   calculated externally to that algorithm, which would then be supplied
   to the algorithm implementation when calculating and verifying
   signatures.  Since then, EdDSA [RFC8032], ML-DSA [FIPS20], and SLH-
   DSA [FIPS205], have also been standardised, and these algorithms
   support both a "pure" and "pre-hash" mode.  In the pre-hash mode, a
   message digest (the "pre-hash") is calculated separately and supplied
   to the signature algorithm as described above.  In the pure mode, the
   message to be signed or verified is instead supplied directly to the
   signature algorithm.  When EdDSA [RFC8419], SLH-DSA [RFC9814], and
   ML-DSA [RFC9882] are used with CMS, only the pure mode of those

Van Geest & Turner         Expires 8 May 2026                   [Page 4]
Internet-Draft              FN-DSA in the CMS              November 2025

   algorithms is specified.  This is because in most situations, CMS
   signatures are computed over a set of signed attributes that contain
   a hash of the content, rather than being computed over the message
   content itself.  Since signed attributes are typically small, use of
   pre-hash modes in the CMS would not significantly reduce the size of
   the data to be signed, and hence offers no benefit.  This document
   follows that convention and does not specify the use of FN-DSA's pre-
   hash mode ("HashFN-DSA") in the CMS.

3.2.  Signature Generation and Verification

   [RFC5652] describes the two methods that are used to calculate and
   verify signatures in the CMS.  One method is used when signed
   attributes are present in the signedAttrs field of the relevant
   SignerInfo, and another is used when signed attributes are absent.
   Each method produces a different "message digest" to be supplied to
   the signature algorithm in question, but because the pure mode of FN-
   DSA is used, the "message digest" is in fact the entire message.  Use
   of signed attributes is preferred, but the conventions for signed-
   data without signed attributes is also described below for
   completeness.

   When signed attributes are absent, FN-DSA (pure mode) signatures are
   computed over the content of the signed-data.  As described in
   Section 5.4 of [RFC5652], the "content" of a signed-data is the value
   of the encapContentInfo eContent OCTET STRING.  The tag and length
   octets are not included.

   When signed attributes are included, FN-DSA (pure mode) signatures
   are computed over the complete DER [X690] encoding of the SignedAttrs
   value contained in the SignerInfo's signedAttrs field.  As described
   in Section 5.4 of [RFC5652], this encoding includes the tag and
   length octets, but an EXPLICIT SET OF tag is used rather than the
   IMPLICIT \[0\] tag that appears in the final message.  At a minimum,
   the signedAttrs field MUST at minimum include a content-type
   attribute and a message-digest attribute.  The message-digest
   attribute contains a hash of the content of the signed-data, where
   the content is as described for the absent signed attributes case
   above.  Recalculation of the hash value by the recipient is an
   important step in signature verification.

   Section 4 of [RFC9814] describes how, when the content of a signed-
   data is large, performance may be improved by including signed
   attributes.  This is as true for FN-DSA as it is for SLH-DSA,
   although FN-DSA signature generation and verification is
   significantly faster than SLH-DSA.

Van Geest & Turner         Expires 8 May 2026                   [Page 5]
Internet-Draft              FN-DSA in the CMS              November 2025

   FN-DSA has a context string input that can be used to ensure that
   different signatures are generated for different application
   contexts.  When using FN-DSA as specified in this document, the
   context string is set to the empty string.

3.3.  SignerInfo Content

   When using FN-DSA, the fields of a SignerInfo are used as follows:

      |  TODO: Include text on security strength.

   digestAlgorithm:  Per Section 5.3 of [RFC5652], the digestAlgorithm
      field identifies the message digest algorithm used by the signer,
      and any associated parameters.  Each FN-DSA parameter set ...

   : Table 1 shows appropriate SHA-2 and SHA-3 digest

   algorithms for each parameter set.  SHA-512 [FIPS180] MUST be
      supported for use with the variants of FN-DSA in this document.
      SHA-512 is suitable for all FN-DSA parameter sets and provides an
      interoperable option for legacy CMS implementations that wish to
      migrate to use post-quantum cryptography, but that may not support
      use of SHA-3 derivatives at the CMS layer.  However, other hash
      functions MAY also be supported; in particular, SHAKE256 SHOULD be
      supported, as this is the digest algorithm used internally in FN-
      DSA.  When SHA-512 is used, the id-sha512 [RFC5754] digest
      algorithm identifier is used and the parameters field MUST be
      omitted.  When SHAKE256 is used, the id-shake256 [RFC8702] digest
      algorithm identifier is used and the parameters field MUST be
      omitted.  SHAKE256 produces 512 bits of output when used as a
      message digest algorithm in the CMS.

      When signing using FN-DSA without including signed attributes, the
      algorithm specified in the digestAlgorithm field has no meaning,
      as FN-DSA computes signatures over entire messages rather than
      externally computed digests.  As such, the considerations above
      and in Table 1 do not apply.  Nonetheless, in this case
      implementations MUST specify SHA-512 as the digestAlgorithm in
      order to minimise the likelihood of an interoperability failure.
      When processing a SignerInfo signed using FN-DSA, if no signed
      attributes are present, implementations MUST ignore the content of
      the digestAlgorithm field.

      |  TODO: Verify table entries.

Van Geest & Turner         Expires 8 May 2026                   [Page 6]
Internet-Draft              FN-DSA in the CMS              November 2025

     +=====================+========================================+
     | Signature Algorithm | Digest Algorithms                      |
     +=====================+========================================+
     | FN-DSA-512          | SHA-256, SHA-384, SHA-512, SHA3-256,   |
     |                     | SHA3-384, SHA3-512, SHAKE128, SHAKE256 |
     +---------------------+----------------------------------------+
     | FN-DSA-1024         | SHA-512, SHA3-512, SHAKE256            |
     +---------------------+----------------------------------------+

              Table 1: Suitable Digest Algorithms for FN-DSA

   signatureAlgorithm:  The signatureAlgorithm field MUST contain one of
      the FN-DSA signature algorithm OIDs, and the parameters field MUST
      be absent.  The algorithm OID MUST be one of the following OIDs
      described in Section 2:

            +=====================+==========================+
            | Signature Algorithm | Algorithm Identifier OID |
            +=====================+==========================+
            | FN-DSA-512          | id-fn-dsa-512            |
            +---------------------+--------------------------+
            | FN-DSA-10124        | id-fn-dsa-1024           |
            +---------------------+--------------------------+

               Table 2: Signature algorithm identifier OIDs
                                for FN-DSA

      |  TODO: Verify paragraph references.

   signature:  The signature field contains the signature value
      resulting from the use of the FN-DSA signature algorithm
      identified by the signatureAlgorithm field.  The FN-DSA (pure
      mode) signature-generation operation is specified in Section X.X
      of [FIPS206], and the signature-verification operation is
      specified in Section X.X of [FIPS206].  Note that Section 5.6 of
      [RFC5652] places further requirements on the successful
      verification of a signature.

4.  Security Considerations

   The security considerations in [RFC5652] and I-D.turner-lamps-fn-dsa-
   certificates apply to this specification.

   Security of the FN-DSA private key is critical.  Compromise of the
   private key will enable an adversary to forge arbitrary signatures.

      |  TODO: Verify paragraph reference.

Van Geest & Turner         Expires 8 May 2026                   [Page 7]
Internet-Draft              FN-DSA in the CMS              November 2025

   FN-DSA depends on high quality random numbers that are suitable for
   use in cryptography.  The use of inadequate pseudo-random number
   generators (PRNGs) to generate such values can significantly
   undermine the security properties offered by a cryptographic
   algorithm.  For instance, an attacker may find it much easier to
   reproduce the PRNG environment that produced any private keys,
   searching the resulting small set of possibilities, rather than
   brute-force searching the whole key space.  The generation of random
   numbers of a sufficient level of quality for use in cryptography is
   difficult; see Section X.X.X of [FIPS206] for some additional
   information.

      |  TODO: Insert references for active research.

   FN-DSA signature generation uses randomness from two sources: fresh
   random data generated during signature generation, and precomputed
   random data included in the signer's private key.  Inclusion of both
   sources of random data can help mitigate against faulty random number
   generators, side-channel attacks, and fault attacks.  Lack of fresh
   random data during FN-DSA signature generation leads to a
   differential fault attack [BD23].  Side channel attacks and fault
   attacks against FN-DSA are an active area of research XX XX.  Future
   protection against these styles of attack may involve interoperable
   changes to the implementation of FN-DSA's internal functions.
   Implementers SHOULD consider implementing such protection measures if
   it would be beneficial for their particular use cases.

   To avoid algorithm substitution attacks, the CMSAlgorithmProtection
   attribute defined in [RFC6211] SHOULD be included in signed
   attributes.

5.  Operational Considerations

   If FN-DSA signing is implemented in a hardware device such as a
   hardware security module (HSM) or a portable cryptographic token,
   implementers might want to avoid sending the full content to the
   device for performance reasons.  By including signed attributes,
   which necessarily includes the message-digest attribute and the
   content-type attribute as described in Section 5.3 of [RFC5652], the
   much smaller set of signed attributes are sent to the device for
   signing.

6.  IANA Considerations

   For the ASN.1 module in Appendix A, IANA [ is requested/has assigned
   ] the following object identifier (OID) in the "SMI Security for S/
   MIME Module Identifier" registry (1.2.840.113549.1.9.16.0):

Van Geest & Turner         Expires 8 May 2026                   [Page 8]
Internet-Draft              FN-DSA in the CMS              November 2025

               +=========+====================+===========+
               | Decimal | Description        | Reference |
               +=========+====================+===========+
               | TBD     | id-mod-fn-dsa-2026 | This RFC  |
               +---------+--------------------+-----------+

                  Table 3: Object Identifier Assignments

7.  References

7.1.  Normative References

   [CSOR]     NIST, "Computer Security Objects Register", 20 August
              2024, <https://csrc.nist.gov/projects/computer-security-
              objects-register/algorithm-registration>.

   [FIPS206]  "Fast Fourier Transform over NTRU-Lattice-Based Digital
              Signature Algorithm", n.d., <https://www.nist.gov/news-
              events/news/2024/08/nist-releases-first-3-finalized-post-
              quantum-encryption-standards>.

   [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>.

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

   [RFC5754]  Turner, S., "Using SHA2 Algorithms with Cryptographic
              Message Syntax", RFC 5754, DOI 10.17487/RFC5754, January
              2010, <https://www.rfc-editor.org/rfc/rfc5754>.

   [RFC6211]  Schaad, J., "Cryptographic Message Syntax (CMS) Algorithm
              Identifier Protection Attribute", RFC 6211,
              DOI 10.17487/RFC6211, April 2011,
              <https://www.rfc-editor.org/rfc/rfc6211>.

   [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>.

   [RFC8702]  Kampanakis, P. and Q. Dang, "Use of the SHAKE One-Way Hash
              Functions in the Cryptographic Message Syntax (CMS)",
              RFC 8702, DOI 10.17487/RFC8702, January 2020,
              <https://www.rfc-editor.org/rfc/rfc8702>.

Van Geest & Turner         Expires 8 May 2026                   [Page 9]
Internet-Draft              FN-DSA in the CMS              November 2025

   [X690]     ITU-T, "Information Technology -- Abstract Syntax Notation
              One (ASN.1): ASN.1 encoding rules: Specification of Basic
              Encoding Rules (BER), Canonical Encoding Rules (CER) and
              Distinguished Encoding Rules (DER)", ITU-T
              Recommendation X.690, ISO/IEC 8825-1:2021, February 2021,
              <https://www.itu.int/rec/T-REC-X.690>.

7.2.  Informative References

   [BD23]     Bauer, S. and F. D. Santis, "A Differential Fault Attack
              against Deterministic Falcon Signatures", 2023,
              <https://eprint.iacr.org/2023/422>.

   [FIPS180]  "Secure hash standard", National Institute of Standards
              and Technology (U.S.), DOI 10.6028/nist.fips.180-4, 2015,
              <https://doi.org/10.6028/nist.fips.180-4>.

   [FIPS20]   "Module-lattice-based digital signature standard",
              National Institute of Standards and Technology (U.S.),
              DOI 10.6028/nist.fips.204, August 2024,
              <https://doi.org/10.6028/nist.fips.204>.

   [FIPS205]  "Stateless hash-based digital signature standard",
              National Institute of Standards and Technology (U.S.),
              DOI 10.6028/nist.fips.205, August 2024,
              <https://doi.org/10.6028/nist.fips.205>.

   [I-D.ietf-lamps-dilithium-certificates]
              Massimo, J., Kampanakis, P., Turner, S., and B.
              Westerbaan, "Internet X.509 Public Key Infrastructure -
              Algorithm Identifiers for the Module-Lattice-Based Digital
              Signature Algorithm (ML-DSA)", Work in Progress, Internet-
              Draft, draft-ietf-lamps-dilithium-certificates-13, 30
              September 2025, <https://datatracker.ietf.org/doc/html/
              draft-ietf-lamps-dilithium-certificates-13>.

   [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>.

   [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>.

Van Geest & Turner         Expires 8 May 2026                  [Page 10]
Internet-Draft              FN-DSA in the CMS              November 2025

   [RFC8032]  Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
              Signature Algorithm (EdDSA)", RFC 8032,
              DOI 10.17487/RFC8032, January 2017,
              <https://www.rfc-editor.org/rfc/rfc8032>.

   [RFC8419]  Housley, R., "Use of Edwards-Curve Digital Signature
              Algorithm (EdDSA) Signatures in the Cryptographic Message
              Syntax (CMS)", RFC 8419, DOI 10.17487/RFC8419, August
              2018, <https://www.rfc-editor.org/rfc/rfc8419>.

   [RFC9814]  Housley, R., Fluhrer, S., Kampanakis, P., and B.
              Westerbaan, "Use of the SLH-DSA Signature Algorithm in the
              Cryptographic Message Syntax (CMS)", RFC 9814,
              DOI 10.17487/RFC9814, July 2025,
              <https://www.rfc-editor.org/rfc/rfc9814>.

   [RFC9881]  Massimo, J., Kampanakis, P., Turner, S., and B. E.
              Westerbaan, "Internet X.509 Public Key Infrastructure --
              Algorithm Identifiers for the Module-Lattice-Based Digital
              Signature Algorithm (ML-DSA)", RFC 9881,
              DOI 10.17487/RFC9881, October 2025,
              <https://www.rfc-editor.org/rfc/rfc9881>.

   [RFC9882]  Salter, B., Raine, A., and D. Van Geest, "Use of the ML-
              DSA Signature Algorithm in the Cryptographic Message
              Syntax (CMS)", RFC 9882, DOI 10.17487/RFC9882, October
              2025, <https://www.rfc-editor.org/rfc/rfc9882>.

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

Appendix A.  ASN.1 Module

      |  RFC EDITOR: Please replace the reference to I-D.turner-lamps-
      |  fn-dsa-certificates in the ASN.1 module below with a reference
      |  the corresponding published RFC.

Van Geest & Turner         Expires 8 May 2026                  [Page 11]
Internet-Draft              FN-DSA in the CMS              November 2025

   <CODE BEGINS>
   FN-DSA-Module-2026
     { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
       id-smime(16) id-mod(0) id-mod-fn-dsa-2026(TBD1) }

   DEFINITIONS IMPLICIT TAGS ::= BEGIN

   EXPORTS ALL;

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

   sa-fn-dsa-512, sa-fn-dsa-10124
     FROM X509-FN-DSA-2026 -- From [I-D.turner-lamps-fn-dsa-certificates]
     { iso(1) identified-organization(3) dod(6) internet(1)
       security(5) mechanisms(5) pkix(7) id-mod(0)
       id-mod-x509-fn-dsa-2024(TBD2) } ;

   --
   -- Expand the signature algorithm set used by CMS [RFC5911]
   --

   SignatureAlgorithmSet SIGNATURE-ALGORITHM ::= {
     sa-fn-dsa-512 |
     sa-fn-dsa-1024,
     ... }

   SMimeCaps SMIME-CAPS ::= {
     sa-fn-dsa-512.&smimeCaps |
     sa-fn-dsa-1024.&smimeCaps,
     ... }

   END
   <CODE ENDS>

Appendix B.  Examples

   This appendix contains example signed-data encodings.  They can be
   verified using the example public keys and certificates specified in
   Appendix C of I-D.turner-lamps-fn-dsa-certificates.

   The following is an example of a signed-data with a single FN-DSA-512
   signer, with signed attributes included:

      |  TODO: Get Example.

Van Geest & Turner         Expires 8 May 2026                  [Page 12]
Internet-Draft              FN-DSA in the CMS              November 2025

   The following is an example of a signed-data with a single FN-
   DSA-1024 signer, with signed attributes included:

      |  TODO: Get Example.

Acknowledgments

      |  TODO:

   This document was heavily influenced by [RFC8419], [RFC9814], and
   [RFC9881].  Thanks go to the authors of those documents.

Authors' Addresses

   Daniel Van Geest
   CryptoNext Security
   Email: daniel.vangeest@cryptonext-security.com

   Sean
   sn3rd
   Email: sean@sn3rd.com

Van Geest & Turner         Expires 8 May 2026                  [Page 13]