Detectable Quantum Byzantine Agreement for Any Arbitrary Number of Dishonest Parties

Abstract: Reaching agreement in the presence of arbitrary faults is a fundamental problem in distributed computation, which has been shown to be unsolvable if one-third of the processes can fail, unless signed messages are used. In this paper, we propose a solution to a variation of the original BA problem, called Detectable Byzantine Agreement (DBA), that does not need to use signed messages. The proposed algorithm uses what we call $Q$-correlated lists, which are generated by a quantum source device. Once each process has one of these lists, they use them to reach the agreement in a classical manner. Although, in general, the agreement is reached by using $m+1$ rounds (where $m$ is the number of processes that can fail), if less than one-third of the processes fail it only needs one round to reach the agreement.