SHRINCS BIP published for Bitcoin quantum security, but trade-offs remain
A Bitcoin Improvement Proposal for the post-quantum signature scheme SHRINCS has been published, putting a concrete Bitcoin-focused option into the debate over how the network could defend itself against future quantum attacks. The proposal comes from research led by Blockstream, whose team has already tested SHRINCS in production on the Liquid sidechain. Blockstream Research’s Jonas Nick described it as the first concrete post-quantum signature proposal designed specifically for Bitcoin, while also stressing that it is not meant to be Bitcoin’s final signature system and is not optimal in every respect. The core appeal is size. Existing post-quantum schemes endorsed by the National Institute of Standards and Technology are far larger than Bitcoin’s current ECDSA and Schnorr signatures, creating a major throughput problem if deployed directly on-chain. SHRINCS is still much bigger than Schnorr, but materially smaller than many alternatives, and Blockstream’s estimates suggest Bitcoin could still run at roughly 3 transactions per second under SHRINCS, versus 0.5 TPS for ML-DSA and 0.36 TPS for SPHINCS+. The catch is that SHRINCS is still early. Its BIP says the security proof remains unfinished, and the design introduces statefulness, signature growth over time, and a large fallback recovery path if a signing device is lost. Blockstream is also exploring lattice-based signatures and zero-knowledge proof aggregation, which it estimates could lift Bitcoin throughput to 6.7 TPS if combined with SHRINCS.








