SHRINCS Draft Released, Bitcoin Quantum Security Detailed

The draft for the quantum-resistant signature scheme SHRINCS for Bitcoin (BTC) has been released. The SHRINCS working group announced the draft on the 27th via the Bitcoin development mailing list, stating that the document outlines the initial specifications of SHRINCS's cryptographic structure. The draft presents a hash-based quantum-resistant signature method, with a public key size of 48 bytes, stateful signatures ranging from 548 to 4619 bytes, and stateless alternative signatures at 5777 bytes. Quantum-resistant signatures are larger than traditional signatures, reducing the number of transactions that can be included in a block. SHRINCS employs small stateful signatures and adopts a structure that uses larger alternative signatures when the wallet loses the signing state. The draft is based on SHA256 and aims for NIST security category 1. Blockstream reported on August 6 that it reviewed 25,935 parameter combinations to find candidates for SHRINCS's stateless signatures. Unchained reported that SHRINCS has been proposed as a post-quantum signature scheme to reduce the burden on Bitcoin block space. This draft strongly reflects the progression of discussions on quantum-resistant signature schemes for Bitcoin into a concrete document stage. Mainnet implementation will require a soft fork and support from network participants.