Dynamic Byzantine Broadcast in Asynchronous Message-Passing Systems

The
reconfiguration
problem is considered a key challenge in distributed systems, especially in
dynamic
asynchronous message-passing systems. To keep the data reliability and availability in long-lived systems, any protocols should support reconfigurations, to dynamically add resources, or remove old and slow machines with newer faster ones. Previous results in reconfigurations either rely on consensus, or study the problem restricted to crash failures only. However, it is difficult to argue that real-world systems experience crash failures only. In this paper, we study the dynamic reconfiguration problem in fully asynchronous message-passing systems with Byzantine faults. We first specify dynamic Byzantine broadcast, and then specify a clean and explicit liveness condition. We show that dynamic Byzantine broadcast is solvable by presenting a dynamic Byzantine consistent broadcast algorithm and a dynamic Byzantine reliable broadcast algorithm.