ERBFT: Efficient and Robust Byzantine Fault Tolerance

Abstract

Byzantine fault-tolerant (BFT) state machine replication protocol is an important building block in the architecture of highly available distributed computing. In this paper, we present ERBFT, a BFT protocol that can achieve robustness and efficiency. The novelty of ERBFT lies in the following points. Firstly, we design the Order-Match (OM), a new request ordering mechanism that lets both primary and backup conduct request ordering. With OM mechanism, the backup can initiate commitment of requests actively when it recognize the possible malicious primary, instead of relying on the client. Combining OM mechanism with ZLight protocol, ERBFT can achieve agreement with three message delays in gracious case. Secondly, we utilize a lightweight PBFT-like protocol, suspect protocol, to commit requests. When the verification of OM mechanism fails, the backup triggers the suspect protocol to further confirm whether the primary is malicious in order to guarantee robustness. If not, the suspect protocol will commit the request with only two phase (i.e., suspect phase and commit phase), which bypasses the pre-prepare phase. The performance of ERBFT is evaluated via simulations and the result illustrates the outstanding performance of ERBFT in terms of throughput and fault scalability.