Internet-Draft jose-cose-sphincs-plus July 2024
Prorock, et al. Expires 9 January 2025 [Page]
Workgroup:
CBOR Object Signing and Encryption
Internet-Draft:
draft-ietf-cose-sphincs-plus-04
Published:
Intended Status:
Standards Track
Expires:
Authors:
M. Prorock
mesur.io
O. Steele
Transmute
R. Misoczki
Google
M. Osborne
IBM
C. Cloostermans
NXP

SLH-DSA for JOSE and COSE

Abstract

This document describes JOSE and COSE serializations for SLH-DSA, which was derived from SPHINCS+, a Post-Quantum Cryptography (PQC) based digital signature scheme.

This document does not define any new cryptography, only seralizations of existing cryptographic systems described in [FIPS-205].

Note to RFC Editor: This document should not proceed to AUTH48 until NIST completes paramater tuning and selection as a part of the PQC standardization process.

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://cose-wg.github.io/draft-ietf-cose-sphincs-plus/draft-ietf-cose-sphincs-plus.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-ietf-cose-sphincs-plus/.

Discussion of this document takes place on the CBOR Object Signing and Encryption Working Group mailing list (mailto:cose@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/cose/. Subscribe at https://www.ietf.org/mailman/listinfo/cose/.

Source for this draft and an issue tracker can be found at https://github.com/cose-wg/draft-ietf-cose-sphincs-plus.

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 9 January 2025.

1. Introduction

SLH-DSA is derived from Version 3.1 of SPHINCS+, as noted in [FIPS-205].

SPHINCS+ is one of the post quantum cryptography algorithms selected in [NIST-PQC-2022].

TODO: Add complete examples for SLH-DSA-SHA2-128s, SLH-DSA-SHAKE-128s, SLH-DSA-SHA2-128f... ( all of them? really?)

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 SLH-DSA Algorithm Family

The SLH-DSA Signature Scheme is paramaterized to support different security level.

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

Table 1: JOSE algorithms for SLH-DSA
Name alg Description
SLH-DSA-SHA2-128s SLH-DSA-SHA2-128s JSON Web Signature Algorithm for SLH-DSA-SHA2-128s
SLH-DSA-SHAKE-128s SLH-DSA-SHAKE-128s JSON Web Signature Algorithm for SLH-DSA-SHAKE-128s
SLH-DSA-SHA2-128f SLH-DSA-SHA2-128f JSON Web Signature Algorithm for SLH-DSA-SHA2-128f

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

Table 2: COSE algorithms for SLH-DSA
Name alg Description
SLH-DSA-SHA2-128s TBD (requested assignment -51) CBOR Object Signing Algorithm for SLH-DSA-SHA2-128s
SLH-DSA-SHAKE-128s TBD (requested assignment -52) CBOR Object Signing Algorithm for SLH-DSA-SHAKE-128s
SLH-DSA-SHA2-128f TBD (requested assignment -53) CBOR Object Signing Algorithm for SLH-DSA-SHA2-128f

4. The SLH-DSA Key Type

Private and Public Keys are produced to enable the sign and verify opertaions for each of the SLH-DSA Algorithms.

This document requests the registration of the following key types in [IANA.jose]:

Table 3: JSON Web Key Type for SLH-DSA
Name kty Description
SLH-DSA SLH-DSA JSON Web Key Type for the SLH-DSA Algorithm Family.

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

Table 4: COSE Key Type for SLH-DSA
Name kty Description
SLH-DSA TBD (requested assignment 8) COSE Key Type for the SLH-DSA Algorithm Family.

5. Security Considerations

The following considerations SHOULD apply to all parmeter sets described in this specification, unless otherwise noted.

Care should be taken to ensure "kty" and intended use match, the algorithms described in this document share many properties with other cryptographic approaches from related families that are used for purposes other than digital signatures.

5.1. Validating public keys

All algorithms in that operate on public keys require first validating those keys. For the sign, verify and proof schemes, the use of KeyValidate is REQUIRED.

5.2. Side channel attacks

Implementations of the signing algorithm SHOULD protect the secret key from side-channel attacks. Multiple best practices exist to protect against side-channel attacks. Any implementation of the the Sphincs+ signing algorithms SHOULD utilize the following best practices at a minimum:

  • Constant timing - the implementation should ensure that constant time is utilized in operations

  • Sequence and memory access persistance - the implemention SHOULD execute the exact same sequence of instructions (at a machine level) with the exact same memory access independent of which polynomial is being operated on.

  • Uniform sampling - care should be given in implementations to preserve the property of uniform sampling in implementation and to prevent information leakage.

5.3. Randomness considerations

It is recommended that the all nonces are from a trusted source of randomness.

6. IANA Considerations

6.1. Additions to Existing Registries

6.1.1. New COSE Algorithms

6.1.1.1. SLH-DSA-SHA2-128s
  • Name: SLH-DSA-SHA2-128s

  • Label: TBD (requested assignment -51)

  • Value type: int

  • Value registry: [IANA.cose]

  • Description: CBOR Object Signing Algorithm for SLH-DSA-SHA2-128s

6.1.1.2. SLH-DSA-SHAKE-128s
  • Name: SLH-DSA-SHAKE-128s

  • Label: TBD (requested assignment -52)

  • Value type: int

  • Value registry: [IANA.cose]

  • Description: CBOR Object Signing Algorithm for SLH-DSA-SHAKE-128s

6.1.1.3. SLH-DSA-SHA2-128f
  • Name: SLH-DSA-SHA2-128f

  • Label: TBD (requested assignment -53)

  • Value type: int

  • Value registry: [IANA.cose]

  • Description: CBOR Object Signing Algorithm for SLH-DSA-SHA2-128f

6.1.2. New COSE Key Types

6.1.2.1. SLH-DSA
  • Name: SLH-DSA

  • Label: TBD (requested assignment 8)

  • Value type: int

  • Value registry: [IANA.cose]

  • Description: COSE Key Type for the SLH-DSA Algorithm Family

6.1.3. New JOSE Algorithms

IANA is requested to add the following entries to the JSON Web Signature and Encryption Algorithms Registry. The following completed registration templates are provided as described in RFC7518.

6.1.3.1. SLH-DSA-SHA2-128s
6.1.3.2. SLH-DSA-SHAKE-128s
6.1.3.3. SLH-DSA-SHA2-128f

6.1.4. New JOSE Key Types

IANA is requested to add the following entries to the JSON Web Key Types Registry. The following completed registration templates are provided as described in RFC7518 RFC7638.

6.1.4.1. SLH-DSA
  • "kty" Parameter Value: SLH-DSA

  • Key Type Description: JSON Web Key Type for the SLH-DSA Algorithm Family.

  • JOSE Implementation Requirements: Optional

  • Change Controller: IETF

  • Specification Document(s): RFC XXXX

6.1.5. New JSON Web Key Parameters

IANA is requested to add the following entries to the JSON Web Key Parameters Registry. The following completed registration templates are provided as described in RFC7517, and RFC7638.

6.1.5.1. ML-DSA Public Key
  • Parameter Name: pub

  • Parameter Description: Public or verification key

  • Used with "kty" Value(s): SLH-DSA

  • Parameter Information Class: Public

  • Change Controller: IETF

  • Specification Document(s): RFC XXXX

6.1.5.2. ML-DSA Secret Key
  • Parameter Name: priv

  • Parameter Description: Secret, private or signing key

  • Used with "kty" Value(s): SLH-DSA

  • Parameter Information Class: Private

  • Change Controller: IETF

  • Specification Document(s): RFC XXXX

7. References

7.1. Normative References

[IANA.cose]
IANA, "CBOR Object Signing and Encryption (COSE)", <http://www.iana.org/assignments/cose>.
[IANA.jose]
IANA, "JSON Object Signing and Encryption (JOSE)", <http://www.iana.org/assignments/jose>.
[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>.
[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>.

7.2. Informative References

[FIPS-205]
"Stateless Hash-Based Digital Signature Standard", n.d., <https://csrc.nist.gov/pubs/fips/205/ipd>.
[NIST-PQC-2022]
"Selected Algorithms 2022", n.d., <https://csrc.nist.gov/Projects/post-quantum-cryptography/selected-algorithms-2022>.

Appendix A. Examples

A.1. JOSE

A.1.1. Key Pair

{
  "kty": "SLH-DSA",
  "alg": "SLH-DSA-SHA2-128s",
  "pub": "V53SIdVF...uvw2nuCQ",
  "priv": "V53SIdVF...cDKLbsBY"
}
Figure 1: Example SLH-DSA-SHA2-128s Private JSON Web Key
{
  "kty": "SLH-DSA",
  "alg": "SLH-DSA-SHA2-128s",
  "pub": "V53SIdVF...uvw2nuCQ"
}
Figure 2: Example SLH-DSA-SHA2-128s Public JSON Web Key

A.1.3. JSON Web Signature

eyJhbGciOiJ...LCJraWQiOiI0MiJ9\
.\
eyJpc3MiOiJ1cm46d...XVpZDo0NTYifQ\
.\
5MSEgQ0dZB4SeLC...AAAAAABIhMUE
Figure 4: Example SLH-DSA-SHA2-128s Compact JSON Web Signature

A.2. COSE

A.2.1. Key Pair

{                                   / COSE Key                    /
  1: 8,                             / SLH-DSA Key Type            /
  3: -51,                           / SLH-DSA-SHA2-128s Algorithm /
  -13: h'7803c0f9...3f6e2c70',      / SLH-DSA Private Key         /
  -14: h'7803c0f9...3bba7abd',      / SLH-DSA Public Key          /
}
Figure 5: Example SLH-DSA-SHA2-128s Private COSE Key
{                                   / COSE Key                    /
  1: 8,                             / SLH-DSA Key Type            /
  3: -51,                           / SLH-DSA-SHA2-128s Algorithm /
  -13: h'7803c0f9...3f6e2c70'       / SLH-DSA Private Key         /
}
Figure 6: Example SLH-DSA-SHA2-128s Public COSE Key

A.2.3. COSE Sign 1

{        / Protected                   /
  1: -51 / SLH-DSA-SHA2-128s Algorithm /
}
Figure 7: Example SLH-DSA-SHA2-128s COSE Protected Header
18(                                 / COSE Sign 1            /
    [
      h'a10139d902',                / Protected              /
      {},                           / Unprotected            /
      h'66616b65',                  / Payload                /
      h'53e855e8...0f263549'        / Signature              /
    ]
)
Figure 8: Example SLH-DSA-SHA2-128s COSE Sign 1

Acknowledgments

TODO acknowledge.

Authors' Addresses

Michael Prorock
mesur.io
Orie Steele
Transmute
Rafael Misoczki
Google
Michael Osborne
IBM
Christine Cloostermans
NXP