Abstract: Aiming at the problem that the classical blockchain consensus mechanism is under the threat of quantum computing attacks,a quantum-secured Byzantine fault tolerant consensus mechanism is proposed.Firstly,to solve the security threat of public key digital signature,this paper proposes a multilinear hash-unconditionally secure signature(MH-USS) signature scheme based on quantum key distribution (QKD) and multilinear hash function family.In this scheme,quantum keys are distributed through QKD network,messages and signatures are transmitted through classical network,and the simplified USS signature scheme is adopted as the main framework,combined with the family of multiple linear hash functions,to generate a new USS scheme.This signature scheme has the characteristics of unforgeability,non-repudiation and transferability.Moreover,this scheme can be implemented on existing equipment and has high practical value.Secondly,in view of the relatively low consensus efficiency of the classical Byzantine fault-tolerant consensus mechanism PBFT,this paper proposes the quantum secured-byzantine fault tolerance(QS-BFT) consensus mechanism.By adding “fast-normal” consensus mode and allowing nodes to vote on empty blocks,the system communication times are reduced and the view conversion process is avoided.It has been proved that this scheme not only guarantees the safety and liveness,but also effectively reduces message complexity and improves consensus efficiency.The simulation and performance test for this scheme indicate that the throughput of this scheme is higher and the delay is lower compared with the PBFT consensus mechanism which is based on the MH-USS signature scheme.

Key words: Blockchain, Consensus protocol, Digital signatures, Quantum key distribution, Unconditionally secure