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 working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. 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." Hollebeek, et al. Expires 20 December 2026 [Page 1] Internet-Draft Use of ML-DSA in TLS 1.3 June 2026 This Internet-Draft will expire on 20 December 2026. Copyright Notice Copyright (c) 2026 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 . . . . . . . . . . . . . . . . . . . . . . . . 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. Hollebeek, et al. Expires 20 December 2026 [Page 2] Internet-Draft Use of ML-DSA in TLS 1.3 June 2026 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]. Hollebeek, et al. Expires 20 December 2026 [Page 3] Internet-Draft Use of ML-DSA in TLS 1.3 June 2026 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 Hollebeek, et al. Expires 20 December 2026 [Page 4] Internet-Draft Use of ML-DSA in TLS 1.3 June 2026 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, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [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, . 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, . [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, . Hollebeek, et al. Expires 20 December 2026 [Page 5] Internet-Draft Use of ML-DSA in TLS 1.3 June 2026 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 Hollebeek, et al. Expires 20 December 2026 [Page 6]