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 the information-theoretic security of 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 proposed in \cite{yin2023QDS}, 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) \cite{weng2023beatingQBA}, 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.