Stateless Hash-Based Digital Signature Algorithm
SLH-DSA, standardized by NIST as FIPS 205 in 2024, is a post-quantum signature scheme derived from the SPHINCS+ submission. Its security rests only on the strength of hash functions, a very conservative assumption, and unlike earlier hash-based schemes it requires no state tracking between signatures. The tradeoff is larger signatures and slower signing than ML-DSA, so it serves as a hedge in case lattice cryptography is ever broken.