Bitcoin Bolsters Quantum Security with QSB and SHRINCS Tests
Bitcoin's quantum-security work took significant strides on August 26, with StarkWare publishing a mined Bitcoin transaction using its Quantum-Safe Bitcoin method (QSB). This development allows for an extra hash-based lock to be added without changing Bitcoin's consensus rules. However, the method comes with a high computing cost of $75 to $150 in cloud GPU costs and requires significant time for the public key to remain hidden.
The SHRINCS (Shrunken SPHINCS) proposal targets Bitcoin's block-space limits and hardware-wallet constraints by using a 48-byte public key. Its specification currently reads 'BIP: ?', 'Status: Draft', and 'Assigned: ?'. The proposal is still in its early stages, with the security proof remaining unfinished.
The broader quantum-security discussion now includes three separate pieces. QSB offers a specialized transaction method under current rules, while SHRINCS provides a candidate signature scheme for protocol review. BIP-361 proposes a process for moving funds away from quantum-vulnerable signatures and is dependent on an approved post-quantum signature standard and output type.