Make Every Word Count: Adaptive BA with Fewer Words

Abstract

Byzantine Agreement is a key component in many distributed systems. While Dolev and Reischuk have proven a long time ago that quadratic communication complexity is necessary for worst-case runs, the question of what can be done in practically common runs with fewer failures remained open. In this paper we present the first Byzantine Broadcast algorithm with ( ( +1)) communication complexity, where 0 ≤ ≤ is the actual number of process failures in a run. And for BA with strong unanimity, we present the first optimal-resilience algorithm that has linear communication complexity in the failure-free case and a quadratic cost otherwise.CCS Concepts: • Theory of computation → Distributed algorithms.