Optimised quantum-resistant signature protocol for Bitcoin using CSIDH

Abstract

This paper proposes a quantum-resistant signature protocol tailored for Bitcoin transactions, leveraging the commutative supersingular isogeny Diffie-Hellman (CSIDH) cryptographic system. By achieving a key size of 64 bytes and a signature size of 128 bytes, the protocol realises up to an 80% reduction in combined key and signature storage overhead compared to SPHINCS+. Benchmark results further reveal a 50% improvement in signing throughput relative to SPHINCS+, while maintaining comparable verification performance. These findings underscore the practical benefits of adopting quantum-resistant cryptographic solutions and highlight the protocol's potential to secure blockchain systems in the post-quantum era.