Implementing an information-theoretically secure Byzantine agreement with quantum signed message solution

Abstract

Byzantine agreement (BA) enables all honest nodes in a decentralized network to reach consensus. In the era of emerging quantum technologies, classical cryptography-based BA protocols face inherent security vulnerabilities. By leveraging information-theoretically secure keys generated by quantum processing, such as quantum key distribution (QKD), and utilizing the one-time pad (OTP) and one-time universal hashing (OTUH) classical methods, we propose a quantum signed Byzantine agreement (QSBA) protocol based on the quantum signed message (QSM) scheme. This protocol achieves information-theoretic security using only QKD-shared key resources between network nodes, without requiring quantum entanglement or other advanced quantum resources. Compared to the recently proposed quantum Byzantine agreement (QBA), our QSBA achieves superior fault tolerance, extending the threshold from nearly 1/2 to an arbitrary number of malicious nodes. Furthermore, our QSBA significantly reduces communication complexity under the same number of malicious nodes. Simulation results in a 5-node twin-field QKD network highlight the efficiency of our protocol, showcasing its potential for secure and resource-efficient consensus in quantum networks.