Timing analysis of leader-based and decentralized Byzantine consensus algorithms

We consider the Byzantine consensus problem in a partially synchronous system with strong validity. For this problem, two main algorithms—with different resilience—are described in the literature. These two algorithms assume a leader process. A decentralized variant (variant without leader) of these two algorithms has also been given in a previous paper. Here, we compare analytically, in a round-based model, the leader-based variant of these algorithms with the decentralized variant. We show that, in most cases, the decentralized variant of the algorithm has a better worst-case execution time. Moreover, for the practically relevant case t≤2 (where t is the maximum number of Byzantine processes), this worst-case execution time is even at least as good as the execution time of the leader-based algorithms in fault-free runs.