Use of ML-DSA in TLS 1.3
draft-ietf-tls-mldsa-04

Transport Layer Security                                    T. Hollebeek
Internet-Draft                                                  DigiCert
Intended status: Informational                                S. Schmieg
Expires: 20 December 2026                                         Google
                                                        B. E. Westerbaan
                                                              Cloudflare
                                                            18 June 2026

                        Use of ML-DSA in TLS 1.3
                        draft-ietf-tls-mldsa-04

Abstract

   This memo specifies how the post-quantum signature scheme ML-DSA
   (FIPS 204) is used for authentication in TLS 1.3.

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://tlswg.github.io/tls-mldsa/draft-ietf-tls-mldsa.html.  Status
   information for this document may be found at
   https://datatracker.ietf.org/doc/draft-ietf-tls-mldsa/.

   Discussion of this document takes place on the Transport Layer
   Security Working Group mailing list (mailto:tls@ietf.org), which is
   archived at https://mailarchive.ietf.org/arch/browse/tls/.  Subscribe
   at https://www.ietf.org/mailman/listinfo/tls/.

   Source for this draft and an issue tracker can be found at
   https://github.com/tlswg/tls-mldsa.

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
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   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
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   This Internet-Draft will expire on 20 December 2026.

Copyright Notice

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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   2
   3.  ML-DSA SignatureScheme Values . . . . . . . . . . . . . . . .   3
     3.1.  Certificate Chain . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Handshake Signature . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The Module-Lattice-Based Digital Signature Algorithm (ML-DSA) is a
   post-quantum digital signature algorithm standardised by the US
   National Institute of Standards and Technology (NIST) in [FIPS204].

   This memo specifies how ML-DSA can be negotiated for authentication
   in TLS 1.3 via the signature_algorithms and signature_algorithms_cert
   extensions.

2.  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.

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3.  ML-DSA SignatureScheme Values

      |  Note to RFC editor: References to RFC 8446 are to be updated to
      |  reference RFC 9846 (RFC 8446bis) once it is published.
      |  Section references need to be updated accordingly.  PR:
      |  https://github.com/tlswg/tls-mldsa/pull/25
      |  (https://github.com/tlswg/tls-mldsa/pull/25)

   As defined in [RFC8446], the SignatureScheme namespace is used for
   the negotiation of signature scheme for authentication via the
   signature_algorithms and signature_algorithms_cert extensions.  This
   document maps three new SignatureScheme values for the three ML-DSA
   parameter sets listed in Section 4, Table 1 of [FIPS204] to the
   SignatureAlgorithmIdentifiers from [RFC9881] as follows.

      +=================+===========+===============================+
      | SignatureScheme | FIPS 204  | Signature AlgorithmIdentifier |
      +=================+===========+===============================+
      | mldsa44(0x0904) | ML-DSA-44 | id-ML-DSA-44                  |
      |                 |           | (2.16.840.1.101.3.4.3.17)     |
      +-----------------+-----------+-------------------------------+
      | mldsa65(0x0905) | ML-DSA-65 | id-ML-DSA-65                  |
      |                 |           | (2.16.840.1.101.3.4.3.18)     |
      +-----------------+-----------+-------------------------------+
      | mldsa87(0x0906) | ML-DSA-87 | id-ML-DSA-87                  |
      |                 |           | (2.16.840.1.101.3.4.3.19)     |
      +-----------------+-----------+-------------------------------+

                    Table 1: SignatureSchemes for ML-DSA

   Note that these are different from the HashML-DSA pre-hashed variants
   defined in Section 5.4 of [FIPS204], which are not used here because
   of the reasons laid out in Section 8.3 of [RFC9881].

3.1.  Certificate Chain

   For the purpose of signalling support for signatures on certificates
   as per Section 4.2.3 of [RFC8446], these values indicate support for
   signing using the given AlgorithmIdentifier shown in Table 1 as
   defined in [RFC9881].

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3.2.  Handshake Signature

   When one of those SignatureScheme values is used in a
   CertificateVerify message, then the signature MUST be computed and
   verified as specified in Section 4.4.3 of [RFC8446], using Algorithm
   2 (ML-DSA.Sign) and Algorithm 3 (ML-DSA.Verify) of [FIPS204]
   respectively.  The context (ctx) parameter MUST be the empty string.
   Note that the context parameter of FIPS 204 is different from the
   context string of Section 4.4.3 of [RFC8446].

   The corresponding end-entity certificate MUST use the corresponding
   AlgorithmIdentifier from Table 1 in its SubjectPublicKeyInfo.

   The context parameter defined in [FIPS204] Algorithm 2 and 3 MUST be
   the empty string.  Note that the context parameter of FIPS 204 is
   different from the context string of Section 4.4.3 of [RFC8446].

4.  Security Considerations

   The security considerations described in Appendices C.2 and E.1 of
   [RFC8446] and Section 4.4.3 of [RFC8446] apply.  In particular,
   signature-based modes of TLS depend on the signature scheme being
   secure against chosen message attacks [SIGMA].  Per Section 3.1 of
   [FIPS204], ML-DSA is designed to meet this property.

   Implementation failures, such as side channels, in cryptographic
   primitives can also compromise the primitive and thus a TLS
   connection depending on it.  Sections 3.4 and 3.6 of [FIPS204]
   discuss additional considerations for implementing ML-DSA, including
   guidance on the choice of hedged vs deterministic variants.  These
   considerations apply when ML-DSA is used for TLS.

5.  IANA Considerations

   This document requests new entries to the TLS SignatureScheme
   registry, according to the procedures in Section 6 of [RFC9847].

          +========+=============+=============+================+
          | Value  | Description | Recommended | Reference      |
          +========+=============+=============+================+
          | 0x0904 | mldsa44     | N           | This document. |
          +--------+-------------+-------------+----------------+
          | 0x0905 | mldsa65     | N           | This document. |
          +--------+-------------+-------------+----------------+
          | 0x0906 | mldsa87     | N           | This document. |
          +--------+-------------+-------------+----------------+

                                  Table 2

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6.  References

6.1.  Normative References

   [FIPS204]  "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>.

   [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>.

   [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>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/rfc/rfc8446>.

   [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>.

6.2.  Informative References

   [RFC9847]  Salowey, J. and S. Turner, "IANA Registry Updates for TLS
              and DTLS", RFC 9847, DOI 10.17487/RFC9847, December 2025,
              <https://www.rfc-editor.org/rfc/rfc9847>.

   [SIGMA]    Krawczyk, H., "SIGMA: The ‘SIGn-and-MAc’ Approach to
              Authenticated Diffie-Hellman and Its Use in the IKE
              Protocols", Springer Berlin Heidelberg, Lecture Notes in
              Computer Science pp. 400-425,
              DOI 10.1007/978-3-540-45146-4_24, ISBN ["9783540406747",
              "9783540451464"], 2003,
              <https://doi.org/10.1007/978-3-540-45146-4_24>.

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Acknowledgments

   Thanks to Alicja Kario, John Mattsson, Rebecca Guthrie, Alexander
   Bokovoy, Niklas Block, Ryan Appel, Loganaden Velvindron, David
   Benjamin, Viktor Dukhovni, Rob Sayre, Daniel Van Geest, Martin
   Thomson, Wang Guilin, and Nick Sullivan for their review and
   feedback.

Authors' Addresses

   Tim Hollebeek
   DigiCert
   Email: tim.hollebeek@digicert.com

   Sophie Schmieg
   Google
   Email: sschmieg@google.com

   Bas Westerbaan
   Cloudflare
   Email: bas@cloudflare.com

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