Internet-Draft ML-DSA for DNSSEC July 2026
Westerbaan & Schmieg Expires 23 January 2027 [Page]
Workgroup:
Domain Name System Operations
Internet-Draft:
draft-westerbaan-dnssec-mldsa-02
Published:
Intended Status:
Standards Track
Expires:
Authors:
B. E. Westerbaan
Cloudflare
S. Schmieg
Google

Module-Lattice Digital Signature Algorithm for DNSSEC

Abstract

This document describes how to specify Module-Lattice-Based Digital Signature Algorithm (ML-DSA) keys and signatures in DNS Security (DNSSEC). It uses the ML-DSA-44 parameter set defined in FIPS 204. ML-DSA-44 is believed to be secure even against adversaries in possession of a cryptographically relevant quantum computer.

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

Discussion of this document takes place on the Domain Name System Operations Working Group mailing list (mailto:dnsop@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/dnsop/. Subscribe at https://www.ietf.org/mailman/listinfo/dnsop/.

Source for this draft and an issue tracker can be found at https://github.com/bwesterb/draft-westerbaan-dnssec-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."

This Internet-Draft will expire on 23 January 2027.

▲

Table of Contents

1. Introduction

DNSSEC, which is broadly defined in [RFC4033], [RFC4034], and [RFC4035], uses cryptographic keys and digital signatures to provide authentication of DNS data. Currently the most popular signature algorithms in use are RSA and the NIST-specified elliptic curve signature algorithm ECDSA [RFC6605].

All currently specified algorithms rely for their security on the hardness of the integer factorization problem or the (elliptic curve) discrete logarithm problem. A cryptographically relevant quantum computer when built would be able to solve both of these problems efficiently, and would therefore be able to forge DNSSEC signatures created with any of these algorithms.

[FIPS204] specifies the Module-Lattice-Based Digital Signature Algorithm (ML-DSA), a signature scheme whose security is based on the hardness of lattice problems over module lattices. ML-DSA is believed to be secure even against adversaries in possession of a cryptographically relevant quantum computer. [FIPS204] defines three parameter sets: ML-DSA-44, ML-DSA-65, and ML-DSA-87.

This document defines the use of DNSSEC's DS, DNSKEY, and RRSIG resource records (RRs) with the ML-DSA-44 parameter set. ML-DSA-44 targets NIST security category 2, which equates to 160 bits of security classical and post-quantum security. ML-DSA-44 has the smallest keys and signatures of the three ML-DSA parameter sets, which makes it the most suitable for use in the DNS.

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.

3. DNSKEY Resource Records

An ML-DSA-44 public key consists of a 1312-octet value as produced by the key generation algorithm ML-DSA.KeyGen defined in Section 5.1 of [FIPS204]. It is encoded into the Public Key field of a DNSKEY resource record as a simple bit string, using the byte encoding of the public key described in Section 7.2 of [FIPS204].

4. RRSIG Resource Records

An ML-DSA-44 signature consists of a 2420-octet value as produced by the signing algorithm ML-DSA.Sign defined in Section 5.2 of [FIPS204]. It is encoded into the Signature field of an RRSIG resource record as a simple bit string, using the byte encoding of the signature described in Section 7.2 of [FIPS204].

Signatures are generated and verified using the "pure" ML-DSA variant (i.e., not the pre-hash variant HashML-DSA) with an empty context string (ctx of zero length), as described in Sections 5.2 and 5.3 of [FIPS204]. The message signed is the data to be signed as described in Section 3.1.8.1 of [RFC4034].

5. Algorithm Number for DS, DNSKEY, and RRSIG Resource Records

The algorithm number associated with the use of ML-DSA-44 in DS, DNSKEY, and RRSIG resource records is TBD1. This registration is fully defined in the IANA Considerations section.

6. Examples

The following example, in the style of Section 6 of [RFC6605], shows an ML-DSA-44 DNSKEY, its corresponding DS record, and an RRSIG over an MX RRset. The key was generated deterministically from the 32-octet seed shown in the PrivateKey field, and the signature was produced using the deterministic variant of ML-DSA (rnd set to all zeroes) so that the example is byte-for-byte reproducible. Because of the size of ML-DSA-44 keys and signatures, the base64-encoded values are wrapped.

Private-key-format: v1.3
Algorithm: 18 (MLDSA44)
PrivateKey: AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8=

example.com. 3600 IN DNSKEY 257 3 18 (
             17K0clSq4NtF55MNSpjSyX2PE5fReJ2voXAksxbpvslPyZRtQvGbeadBO7qj
             PnFJy0LtURVpOsBB+suYit61/g4dhjEYSZW1ksOX0ilOLhT5CqQUujgmiZrE
             P0zMrLwm6agyuVEY1ctDPL75ZgsAE44IF/YediyidMNq1VTrIqrBFi5KsBrL
             oeOMTv2PgLZbMz0PcuVd/nHOnB67mInnxWEGwP1zgDoq7P6v3teqPLLO2lTR
             K9jNNqeM+XWUO0er0l6ICsRS5XQu0ejRqCr6huWQx1jBWuTShA2SvKGlCQ9A
             SWWX/KfYuVE/GhvabpUKqpjeRnUH1KT1pPBZkhZYLDVy9i7aiQWrNYFnDEoC
             d3oz4Mpylf2PT/bRoKOnaD1l9fX3/GDaAj6CbF+SFEwC99G6EHWYdVPqk2f8
             122ZC3+pnNRa/biDbUPkWfUYffBYR5cJoB6mg1k1+nBGCZDNPcG6QBupS6sd
             3kGsZ6szGdysoGBI1MTu8n7hOpwX0FOPQw8tZC3CQVZg3niHfY2KvHJSOXjA
             QuQoX0MZhGxEEmJCl2hEwQ5Va6IVtacZ5Z0MayqW05hZBx/cws3nUkp77a5U
             6FsxjoVOj+Ky8+36yXGRKCcKr9HlBEw6T9r9n/MfkHhLjo5FlhRKDa9YZRHT
             2ZYrnqla8Ze05fxg8rHtFd46W+9fib3HnZEFHZsoFudPpUUx79wcvnTUSIV/
             R2vNWPIcC2U7O3ak4HamVZowJxhVXMY/dIWaq6uSXwI4YcqM0Pe62yhx9n1V
             Mm10URNa1F9KG6aRGPuyyKMO7JOS7z+XcGbJrdXHEMxkexUU0hfZWMcBfD6Q
             /SDATmdLkEhuk3CjGgAdMvRzl55JBnSefkd/oLdFCPil8jeDErg8Jb04jKCw
             //dHi69CtxZn7arJfEaxKWQ+WG5bBVoMIRlG1PNuZ1vtWGD6BCoxXZgmFk1q
             kjfDWl+/SVSQpb1N8ki5XEqud4S2BWcxZqxCRbW0sIKgnpMj5i8geMW3Z4NE
             be/XNq06NwLUmwiYRJAKYYMzl7xEGbMNepegs4fBkRR0xNQbU+Mql3rLbw6n
             XbZbs55Z5wHnaVfe9vLURVnDGncSK1IE47XCGfFoixTtC8C4AbPm6C3NQ+nA
             6fQXRM2YFb0byIINi7Ej8E+s0bG2hd1aKxuNu/PtkzZw8JWhgLTxktCLELj6
             u9/MKyRRjjLuoKXgyQTKhEeACD87DNLQuLavZ7w1W5SUAl3HsKePqA46Lb/r
             UTKIUdYHgZjpSTZRrnh+wCUfkiujDp9R32Km1yeEzz3SBTkxdt+jJKUSvZSX
             CjbdNKUUqGeR8Os28BRbCatkZRtKAxOymWEaKhxIiRYnWYdooxFAYLpEQ0ht
             9RUioc6IswmFwhb45u0XjdVnswSg1Mr7qIKig0LxepqiauWNtjAIPSw1j99W
             bD9dYqQoVnvJ6ozpXKoPNUdLC/qPM5olCrTfzyCDvo7vvBBV4Y/hU3DuyyYF
             Ztg/8GshGq7EPKKbVMzQD4gVokZe8LRlFcx+QfMSTwnv/3OTCatYspoUWaAL
             zlA46TjJZ49y6w5O5f2q5m2fhXP8l/xCtJWfS/i2HXhDPoawM11ukZHE2L9I
             ezkFwQjP1qwksM633LfPUfhNDtaHuV6uscUzwG8NlwI9kqcIJYN7Wbpst9Tl
             awqHwgOGKujzFbpZJejt76Z5NpoiAnZhUfFqll+fgeznbMBwtVhp5NuXhM8F
             yDCzJCyDEg== )

example.com. 3600 IN DS 59829 18 2 (
             812cb1a22af04380e2f72d91c06c14eb1a918cf30037a8a9c67497e9264b
             4bfa )

example.com. 3600 IN MX 10 mail.example.com.

example.com. 3600 IN RRSIG MX 18 2 3600 (
             1440021600 1438207200 59829 example.com.
             kdySHzwB7NftjQSAF7snCeKau3NoqpLNg16h/eHZV8L3Zpi30lkRyiS4FLMM
             ZqTjzbf1A/bShg4qZpYlnfqXN8uqFWF9GEEJOgte1CFdF4GC05gEBU88Kryf
             nGAcpXKafw9htDxZrqmqVSWN+1guW7HyUUFo1IuWTnZKuhZptDJkq+Ml+5ZH
             y4p+2Tdwk8MH7tJlTYk/UVaM1wIXPB2YgJ++kD0zhys5c38rztcaOmMXt6ej
             yAEY37Dc1Z/KsrRQZWv+XZ/CTliuh+dGJHoGuTm5KwS0us884ukWNC/wIU/S
             dlGoBDVXsT163Tr6lTf8pJ4xixcKIN8nsKSFxP9j+AbaN5SofIAvp4LGIFLg
             MKsRV/cqeYo8PegVD2EhAQ2/HVTO3uO8vlqLK7nWVVK2+2aYKIL2EqzjhRYK
             U5DhMwS9ZgbG0niszGXpvZcNcOyABXysdVuaDjnUuamYVACOUrV786LNmt8I
             WDnXWoPPMErPk5vNyHq6+ZHg79UeZpSzx0Ae/1aIfi2WEta9Or5sGItBn6vF
             Wi9kJRuhuoMIXf9CLBV/LHL/PIenBxXSnr2Owg54AuSN2tmk2lDy8BfKzzvx
             TOoKXx4edo96Xv6QWASAxO9JmyEvhnF3SBI6HG3fn2+k8rgJLIHpsr4pZhMh
             4/SQWaojxt51nEIFi1bl7P6sAmCdMP81LSNx05hIkKcPeO33hA2VSDO7GzOE
             snBOzbhUX9gbFr3aNV/Wrbs/cZMAL1I0IKG20jkmEfZ9PeKN0hXCxHJo4hPF
             L2mm9ciGpuXS7oN8f7YublNTwRY8b4plScVICpyBT5UDOgezR9/+DnklL0fz
             IORMTRnpD1hq4BqZMgNMwvczFg3DrSLQP/cBiKLn3toJrkSuU9aXodEqW3lh
             RdMvDUqTtHgMKas5velmabpENAbixiB8n5zoENnMLV6w/13a+yOTT2WUvESg
             HqF92FfQMdQl36noyewmjUFZopirCGV6AkebdVsTY27DtYkGWamLXcm3w2d6
             AYV/LssvyK/Jlnw/E7YRJWkO+8PvHA2tvfQSr8fNC4ll/KHdwr8d0Q8spPcO
             HMMui20XDYeprPmp64hSt4IBuiQusdm3SQsWjQvaUsg8sykZd24S/wNQiGsw
             XaoG6oWYYCZupfvGc0sgb+9qxZU5fSAYKwx5LjYajruvQ5flebAtrUdLuPbG
             Mb2I7Z8c4IvDmbA6ljqMK60w1XI+wU7jSWzoEaiIeAUR1aT925KFMEhmFG3k
             Tr5ZPI57wM7pEI9jBME80lu7D3f4z++icSHSJ5YNa/+kp7eSIT94m4Tj7nel
             mN0WnKFgzGZKnuiDGJew5FFnfB0qfvqUNUPt1rVaIr7rzBBL4j8WQHqOo17A
             +0pnIqKTe1Z8MxFnPwP1eWHa3T/7JeEPSD5JFOpEWxs12twxTC42BrTCckSm
             rfmksfxmJa0mfflaOPHkjahTprrItJzG1efHYCu5nP5rsclZF0hDOR1OZrgK
             2IhnG1VotIPB4+/+70+uD0qcqY3L2yonxFlQS8sEmMcXi9xQTxdFG4NOk/TQ
             G50Oly1tRp9UoLjwTDtlIjh71Lz9lajbAabV4WtIvd7cwaREO0kFAtzIgfJR
             VMasWvUo6e93qQBThzvkCNs8ngsa0jXJL1HrERP+qkiULCDMr19FVimWmIzL
             CkR9pg9WWjruY5krgdVbINUqjsyyGriPEhy2JneNWdOdFoAwkWtGbIpQhHs2
             bLHpG9xPPF+ElqLmjNa76BhXv4caurHYn7K0m4NMVgDywGXoh0OGe/PoXQ4g
             Ht7EbHgbCQO9V8+/1+MWw9ZrU6btOGJ2JVXeyRXYyJarn+cnPL1nWOlq7bMD
             3mazOTNZPc5UENSvDL51hmd3WD71i2u9btqIzjnmSxggPHRsVcOaGXHM3aUJ
             nrDtwi1EY7THlJatS+ItjWQMCDh8g/4LF9S2UWGFc21MimswWvgh1jB/4hYI
             9C8PSCpAeV26dXoANntR/lLms42488dVJ1wyNGjaNNX1itiqFYsNUn3LyT3T
             dVUgBwkfzO1I4UnhDIbsHJWbs7Dl/52Ei4MbpPJXnL1gMNc6SD1EkT1CeY9f
             esHF20wr8tb7V+qPO2TCE26syB9lZ41OSOYgqPYK/OHyoLedQmTOFls0QMj2
             F0bks3pJm/TDDMEuUdhulPatnZBNIXexqNImQUFyipcJ9W5KnD6Wr5+jyULy
             VBQRpWPzipfPFACb5d5lWPtrvh4kurYt3sSdUy+WJKuYb1roxXTZJqP0QDgn
             VEYL5nJnxqSRD9fx7HMRHXODkVioBFmSUgwP5XBljn/YpIgG8Ix42hyKMCti
             yv1gIY3/m8cfHyj5I6xcDHUTZHyM9+KSZeipf6wUnngoZuYzP9N3Nozo8LI+
             w3Mo6s/VjhmsALOYcus720s0MQY5prhkcZYUvgv9YL9R+1Fm7Kxy3cjpnGqy
             WwxN6YmNw/f6C+21Dlex7+09o2ygi0M1NEZZ0FhdaBmxVxtSjbBm3uKu9taW
             0zO534HXlifFkxf6GhboxbGdm1yekVIjDLnC+iodQyLwIi0vvc435Xk4GRBs
             8D5Pxf3vT3tgPy5sDXbJ3lT58MekKdT/HobugDOdu0ltGenFjnKFhdJudvQ/
             FFjqJk1HYnjxxdP3QYKlSHOv2ADtRqgI0VHLJmECOifYr90uWml1uzaUzK0X
             Tulm8fn6lfpF3EWJYSsq1iXQWuiRw9u6dxiS02+c4Z8Nzumoh48W+z0GFy+q
             ClyhqdedA6k3WZIJi919e5b24mj5rqzcgrA6KMqnTJDKh2cuoKC1fI88w774
             co0XPDyg+v/RD2ET1fquDGHjeVyVBsknNZQ5lwvLeAy/uH+Ql5qECQ9WCIJP
             ydZZhB906hkHZ+vch1fG+vhgMtoXhtZ4UXzQwbJBL/4wxtOau3IgWGkJEImJ
             PK3KE+7phfn5YmGSjVCp8o1t2QxpwJ1ZPBuTrUWy15gruIP8e415f0UPUZjF
             G+p6JqsUzaBzgZvAg9nY/vHEC0sXuC7lnqmDxr8LU9JMD77XrBccXMP199d/
             10bJW8TH+yzqE4syjdUPEalQnwP/fh9us92eSdv50vr0/KPhzfWzcRwWFxof
             S15zlJe3xNj+BAURHCApKjBkh5emuLy+w9zn6vn6/QsbXWp6hZWcoLO6ytLf
             6/H+DhguNzs/VFVbg5SXo62wztPoAAAAAAAAAAAAAA0jNEY= )

7. Security Considerations

7.1. ML-DSA

The security considerations of [FIPS204] apply.

In particular 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 DNSSEC and especially during online signing.

7.2. Downgrades

Section 5.11 of [RFC6840] recommends validators to accept any single valid path. Such lenient validators are vulnerable to a downgrade attack: if a zone is signed by ML-DSA-44 and a quantum-vulnerable algorithm, then a quantum attacker can strip the ML-DSA-44 signatures, and have the lenient validator accept the forged quantum-vulnerable signature.

This does not apply if the validator does not accept any quantum-vulnerable algorithms or if the zone is only signed by ML-DSA-44.

8. IANA Considerations

This document updates the IANA registry "Domain Name System Security (DNSSEC) Algorithm Numbers". The following entry is to be added to the registry:

Table 1: New DNSSEC Algorithm Number entry
Field Value
Number TBD1
Description ML-DSA-44
Mnemonic MLDSA44
Zone Signing Y
Trans. Sec. *
Use for DNSSEC Signing MAY
Use for DNSSEC Validation MAY
Implement for DNSSEC Signing MAY
Implement for DNSSEC Validation MAY
Reference (this document)

* There has been no determination of standardization of the use of this algorithm with Transaction Security.

9. References

9.1. Normative References

[FIPS204]
National Institute of Standards and Technology (NIST), "Module-Lattice-Based Digital Signature Standard", FIPS PUB 204, , <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, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC4033]
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, DOI 10.17487/RFC4033, , <https://www.rfc-editor.org/rfc/rfc4033>.
[RFC4034]
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, DOI 10.17487/RFC4034, , <https://www.rfc-editor.org/rfc/rfc4034>.
[RFC4035]
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC 4035, DOI 10.17487/RFC4035, , <https://www.rfc-editor.org/rfc/rfc4035>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.

9.2. Informative References

[RFC6605]
Hoffman, P. and W.C.A. Wijngaards, "Elliptic Curve Digital Signature Algorithm (DSA) for DNSSEC", RFC 6605, DOI 10.17487/RFC6605, , <https://www.rfc-editor.org/rfc/rfc6605>.
[RFC6840]
Weiler, S., Ed. and D. Blacka, Ed., "Clarifications and Implementation Notes for DNS Security (DNSSEC)", RFC 6840, DOI 10.17487/RFC6840, , <https://www.rfc-editor.org/rfc/rfc6840>.

Acknowledgments

TODO

Authors' Addresses

Bas Westerbaan
Cloudflare
Sophie Schmieg
Google