---
title: "XMSS: which blockchains use it"
url: "https://hardyindex.com/algorithms/xmss"
---

# 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. No post-quantum scheme carries a proof of resistance.
- **Standard:** SP 800-208 and RFC 8391 (NIST, final).
- **Family:** hash based stateful.
- **Also known as:** eXtended Merkle Signature Scheme.

## Rated chains using it

- [Kaspa](https://hardyindex.com/chains/kaspa.md): contract level, testnet, 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 (source code or release): https://github.com/biryukovmaxim/kaspa-xmss
- [Quantum Resistant Ledger](https://hardyindex.com/chains/qrl.md): account signatures, mainnet, mandatory. Source (statement or write-up): https://www.theqrl.org/2/

## Sources

- [RFC 8391: XMSS: eXtended Merkle Signature Scheme](https://datatracker.ietf.org/doc/html/rfc8391), IETF. Accessed 19 October 2026.
- [SP 800-208: Recommendation for Stateful Hash-Based Signature Schemes](https://csrc.nist.gov/pubs/sp/800/208/final), NIST. Accessed 19 October 2026.