Abstractions for Devising Byzantine-Resilient State Machine Replication

Assia Doudou, Rachid Guerraoui, Benoît Garbinato

Abstract: State machine replication is a common approach for making a distributed service highly available and resilient to failures, by replicating it on different processes. It is well known, however that the difficulty of ensuring the safety and liveness of a replicated service increases significantly when no synchrony assumptions are made, and when processes can exhibit Byzantine behaviors. The contribution of the work is to break the complexity of devising a Byzantine-resilient state machine replication protocol, by decomposing it into key modular abstractions. In addition to being modular, the protocol we propose always preserves safety in the presence of less than one third of Byzantine processes, independently of any synchrony assumptions. As for the liveness of our protocol, it relies on a Byzantine failure detector that encapsulates a sufficient amount of synchrony.