XMSS
A stateful hash-based signature scheme specified in RFC 8391 and approved by NIST in SP 800-208. Each one-time key inside it may sign once, so the signer must track state to avoid reuse.
- Quantum status
- Believed quantum-resistant
- Standard
- SP 800-208 and RFC 8391, final
- Family
- hash based stateful
- Also known as
- eXtended Merkle Signature Scheme
Rated chains using it
- Kaspa Testnet
Contract level, XMSS^MT, two height-12 layers, 192-bit hash (BLAKE3 by default). A core developer's covenant experiment, run against testnet-10 and marked not for production use. Source code or release
- Quantum Resistant Ledger Mainnet, mandatory
Account signatures. Statement or write-up
Sources
- RFC 8391: XMSS: eXtended Merkle Signature Scheme , IETF. Accessed 19 October 2026.
- SP 800-208: Recommendation for Stateful Hash-Based Signature Schemes , NIST. Accessed 19 October 2026.
Published beside the Hardy Score and not an input to it. How each chain is scored is set out in the methodology.