SLH-DSA-128 (FIPS 205 Level 1) Parameter Tier
Parameter-tier sub-spec for SLH-DSA-128 (NIST FIPS 205 security level 1), the smallest hash-based signature variant. Algorithm definition deferred to LP-4500.
Implementation status (code-audited 2026-07-03): SHIPPED Parameters confirmed against luxfi/crypto/slhdsa (circl v1.6.3).
Abstract
SLH-DSA-128 is the NIST FIPS 205 security-level-1 parameter family of the Stateless Hash-based Digital Signature Algorithm (formerly SPHINCS+). This LP pins the tier identifier, covers both the "s" (small) and "f" (fast) sub-variants — SLH-DSA-128s with ~7.85 KB signatures and SLH-DSA-128f with ~17 KB signatures — and points at the algorithm spec in LP-4500. Sizes: public key 32 B, secret key 64 B. Use SLH-DSA-128 for short-lived hash-based signatures where ML-DSA is not appropriate (e.g., wallet recovery seeds, off-chain attestations). For long-lived consensus or institutional signing use SLH-DSA-192 (LP-4520) or SLH-DSA-256 (LP-4530).
Reference implementation
- Primitive:
luxfi/crypto/slhdsa/slhdsa128 - Hash backend: SHA2-256 or SHAKE128
- Test vectors: NIST KAT vectors (FIPS 205 Appendix B)
Provenance
Originally LP-4410, renumbered 2026-05-18 to consolidate all cryptographic primitives into the 4xxx range with family sub-ranges (PQ hash signatures 4500-4599). Original created date: 2026-05-18 (no prior history before this renumber). The 4410 slot is retained as a permanent pointer to this LP.
Copyright
Copyright and related rights waived via CC0.