Algorithm

SHRINCS

Family: hash-based.

SHRINCS is a hash-based signature scheme designed for Bitcoin. It joins two parts under one public key. A compact stateful part is used while the signer's state is intact. A larger stateless part acts as a fallback after the state is lost, for example after a restore from a seed backup. A signature from one part is enough to verify.

Safety: High

Why this rating

Security rests only on the properties of the hash function, which is SHA-256 in the draft. The stateful path has one-time-key reuse risk if state is mishandled, which the stateless fallback is meant to reduce. The design is a new draft: the specification says a security proof is still to be written.

Standard

https://github.com/SHRINCS/shrincs-bip/blob/main/SHRINCS.md

Research

• Hash-based Signature Schemes for Bitcoin (2025, Appendix B.3 describes the construction)
• SHRINCS: 324-byte stateful post-quantum signatures with static backups (Delving Bitcoin)
• SHRINCS: A Compact Hash-Based Signature Scheme (draft specification)

Implemented by

• hashsigs
• pqhybridsign