| Internet-Draft | SLH-DSA for JOSE and COSE | October 2025 |
| Prorock, et al. | Expires 8 April 2026 | [Page] |
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.¶
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/.¶
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This document describes JSON Object Signing and Encryption (JOSE) [RFC7515] and CBOR Object Signing and Encryption (COSE) [RFC9052] serializations for the Stateless Hash-Based Digital Signature Standard (SLH-DSA), which was derived from Version 3.1 of SPHINCS+, a Post-Quantum Cryptography (PQC) based digital signature scheme standardized in [FIPS-205].¶
This document does not define any new cryptography.¶
This document builds on the Algorithm Key Pair (AKP) type, as defined in [I-D.ietf-cose-dilithium]. The AKP type enables flexible representation of keys used across different post-quantum cryptographic algorithms, including SLH-DSA.¶
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.¶
The SLH-DSA Signature Scheme is parameterized to support different security levels.¶
This document requests the registration of the following algorithms in [IANA.JOSE]:¶
| 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.JOSE]:¶
| Name | alg | Description |
|---|---|---|
| SLH-DSA-SHA2-128s | TBD1 (-51) | CBOR Object Signing Algorithm for SLH-DSA-SHA2-128s |
| SLH-DSA-SHAKE-128s | TBD2 (-52) | CBOR Object Signing Algorithm for SLH-DSA-SHAKE-128s |
| SLH-DSA-SHA2-128f | TBD3 (-53) | CBOR Object Signing Algorithm for SLH-DSA-SHA2-128f |
Private and public keys are produced to enable the sign and verify operations for each of the SLH-DSA algorithms.¶
The SLH-DSA Algorithm Family uses the Algorithm Key Pair (AKP) key type, as defined in [I-D.ietf-cose-dilithium]. This ensures compatibility across different cryptographic algorithms that use AKP for key representation.¶
The specific algorithms for SLH-DSA, such as SLH-DSA-SHA2-128s, SLH-DSA-SHAKE-128s, and SLH-DSA-SHA2-128f, are defined in this document and are used in the alg value of an AKP key representation to specify the corresponding algorithm.¶
Thumbprints for SLH-DSA keys are computed according to the process described in [I-D.ietf-cose-dilithium].¶
The security considerations of [RFC7515], [RFC7517] and [RFC9053] apply to this specification as well.¶
A detailed security analysis of SLH-DSA is beyond the scope of this specification; see [FIPS-205] for additional details.¶
The following considerations apply to all parameter sets described in this specification.¶
All algorithms that operate on public keys require validation before use. For sign, verify and proof schemes, the use of KeyValidate is REQUIRED.¶
Implementations of the signing algorithm SHOULD protect the secret key from side-channel attacks. Any implementation of SLH-DSA signing algorithms SHOULD employ at least the following best practices:¶
All nonces MUST originate from a trusted and cryptographically secure source of randomness.¶
IANA is requested to add the following entries to the COSE Algorithms Registry.¶
The following registration templates are provided in accordance with the procedures described in [RFC9053] and [RFC9054].¶
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].¶
{
"kty": "AKP",
"alg": "SLH-DSA-SHA2-128s",
"pub": "V53SIdVF...uvw2nuCQ",
"priv": "V53SIdVF...cDKLbsBY"
}
{
"kty": "AKP",
"alg": "SLH-DSA-SHA2-128s",
"pub": "V53SIdVF...uvw2nuCQ"
}
eyJhbGciOiJ...LCJraWQiOiI0MiJ9\ .\ eyJpc3MiOiJ1cm46d...XVpZDo0NTYifQ\ .\ 5MSEgQ0dZB4SeLC...AAAAAABIhMUE
{
1: 7,
3: -51,
-1: h'7803c0f9...3f6e2c70',
-2: h'7803c0f9...3bba7abd'
}
{
1: 7,
3: -51,
-2: h'7803c0f9...3bba7abd'
}
18([
<<{1: -51}>>,
{},
h'66616b65',
h'53e855e8...0f263549'
])
We would like to thank Roy Williams, Cedric Fournet, Simo Sorce, Ilari Liusvaara, Neil Madden, Anders Rundgren, David Waite, and Russ Housley for their review feedback.¶