Title: Optimised quantum-resistant signature protocol for Bitcoin using CSIDH

Authors: Mohammed El Baraka; Siham Ezzouak

Addresses: Faculty of Sciences Dhar Almahraz, Department of Mathematics, University Sidi Mohamed Ben Abdellah, FEZ, 30000, Morocco ' Faculty of Sciences Dhar Almahraz, Department of Mathematics, University Sidi Mohamed Ben Abdellah, FEZ, 30000, Morocco

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.

Keywords: quantum-resistant cryptography; Bitcoin; CSIDH; commutative supersingular isogeny Diffie-Hellman; isogeny-based cryptography; SPHINCS+.

DOI: 10.1504/IJBC.2025.144643

International Journal of Blockchains and Cryptocurrencies, 2025 Vol.6 No.1, pp.18 - 41

Received: 20 Aug 2024
Accepted: 24 Dec 2024
Published online: 25 Feb 2025 *

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