DuoBFT: Resilience vs. Efficiency Trade-off in Byzantine Fault Tolerance.

This paper presents DuoBFT, a Byzantine fault-tolerant protocol that provides two features: Cheaper Resilience and Dual Fault Assumptions. First, by enhancing a fraction of replicas in the system with trusted components, DuoBFT enables commit decisions in the Hybrid fault model with quorums that are about half the size of regular byzantine quorums. Second, DuoBFT exposes both the Hybrid and BFT fault models to the clients and lets them make commit decisions under either of these models. We first enable a notion called Flexible Quorums in the Hybrid fault model by revisiting the quorum intersection requirements in hybrid protocols. We apply the Flexible Quorums technique to MinBFT, a state of the art hybrid protocol, and consequently build on it to achieve DuoBFT.