Quantum Byzantine Agreement for Any 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 $$m+1$$ 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.