FN-DSA for JOSE and COSE

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Table of Contents

1. Introduction

This document specifies JSON Object Signing and Encryption (JOSE) and CBOR Object Signing and Encryption (COSE) serializations for FFT (fast-Fourier transform) over NTRU-Lattice-Based Digital Signature Algorithm (FN-DSA), a Post-Quantum Cryptography (PQC) digital signature scheme defined in US NIST FIPS 206 (expected to be published in late 2026 early 2027).¶

See Section 11.3 of [I-D.draft-ietf-pquip-pqc-engineers] for a comparison of FN-DSA with ML-DSA [USNIST.FIPS.204] and SLH-DSA [USNIST.FIPS.205].¶

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

3. The FN-DSA Algorithm Family

The FN-DSA Signature Scheme is parameterized to support different security levels.¶

This document introduces the registration of the following algorithms in [IANA.jose]:¶

This document introduces the registration of the following algorithms in [IANA.cose]:¶

4. FN-DSA Keys

The FN-DSA Algorithm Family uses the Algorithm Key Pair (AKP) key type, as defined in [I-D.draft-ietf-cose-dilithium].¶

The specific algorithms for FN-DSA, such as FALCON512 and FALCON1024, are defined in this document and are used in the alg value of an AKP key representation to specify the corresponding algorithm.¶

Thumbprints for FN-DSA keys are computed according to the process described in [I-D.draft-ietf-cose-dilithium].¶

5. Security Considerations

The security considerations of [RFC7515], [RFC7517] and [RFC9053] apply to this specification as well.¶

A detailed security analysis of FN-DSA is beyond the scope of this specification; see [USNIST.FIPS.206] for additional details.¶

6. IANA Considerations

7. References

Appendix A. Examples

{
  "kty": "AKP",
  "alg": "FALCON512",
  "pub": "V53SIdVF...uvw2nuCQ",
  "priv": "V53SIdVF...cDKLbsBY"
}

{
  "kty": "AKP",
  "alg": "FALCON512",
  "pub": "V53SIdVF...uvw2nuCQ"
}

{
  "kid: "clpwZ...RWYU9CUF",
  "alg": "FALCON512",
  "typ": "JWT"
}

{
  / kty AKP       / 1: 7,
  / alg FALCON512 / 3: -54,
  / public key    / -1: h'7803c0f9...3f6e2c70',
  / private key   / -2: h'7803c0f9...3bba7abd'
}

{
  / kty AKP       / 1: 7,
  / alg FALCON512 / 3: -54,
  / public key    / -1: h'7803c0f9...3f6e2c70',
}

18([
  <<{
    / alg FALCON512 / 1: -54,
  }>>,
  / unprotected / {},
  / payload / h'66616b65',
  / signature / h'53e855e8...0f263549'
])

Appendix B. Document History

-02¶

• Converted to markdown¶

• Applied feedback from IESG Evaluation on ML-DSA¶

• Revised references¶

• Revised abstract¶

-01¶

• Added Acknowledgements¶

• Added Document History¶

• Updated test vectors¶

Acknowledgments

We would like to especially thank David Balenson for careful review of approaches taken in this document. We would also like to thank Michael B. Jones for guidance in authoring.¶

Contributors

Authors' Addresses