Cryptology ePrint Archive: Report 2018/213

Committing to Quantum Resistance: A Slow Defence for Bitcoin against a Fast Quantum Computing Attack

I. Stewart and D. Ilie and A. Zamyatin and S. Werner and M.F. Torshizi and W.J. Knottenbelt

Abstract: Quantum computers are expected to have a dramatic impact on numerous fields, due to their anticipated ability to solve classes of mathematical problems much more efficiently than their classical counterparts. This particularly applies to domains involving integer factorisation and discrete logarithms, such as public key cryptography. In this paper we consider the threats a quantum-capable adversary could impose on Bitcoin, which currently uses the Elliptic Curve Digital Signature Algorithm (ECDSA) to sign transactions. We then propose a simple but slow commit-delay-reveal protocol, which allows users to securely move their funds from old (non-quantum-resistant) outputs to those adhering to a quantum-resistant digital signature scheme. The transition protocol functions even if ECDSA has already been compromised. While our scheme requires modifications to the Bitcoin protocol, these can be implemented as a soft fork.

Category / Keywords: cryptographic protocols / Bitcoin, blockchain, quantum computing, quantum resistance, ECDSA

Date: received 22 Feb 2018, last revised 26 Feb 2018

Contact author: w knottenbelt at imperial ac uk

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Version: 20180227:040925 (All versions of this report)

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