Making Byzantine consensus live

• Published in: Distributed computing Vol. 35; no. 6; pp. 503 - 532
• Main Authors: Bravo, Manuel, Chockler, Gregory, Gotsman, Alexey
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2022; Springer Nature B.V
• Subjects: Blockchain; Clocks & watches; Communication; Computer Communication Networks; Computer Hardware; Computer Science; Computer Systems Organization and Communication Networks; Digital signatures; Distributed processing; Formal specifications; Guarantees; Software Engineering/Programming and Operating Systems; Synchronism; Theory of Computation; Byzantine consensus; Partial synchrony; Liveness; Blockchain
• ISSN: 0178-2770; 1432-0452
• DOI: 10.1007/s00446-022-00432-y

Partially synchronous Byzantine consensus protocols typically structure their execution into a sequence of views , each with a designated leader process. The key to guaranteeing liveness in these protocols is to ensure that all correct processes eventually overlap in a view with a correct leader for long enough to reach a decision. We propose a simple view synchronizer ion that encapsulates the corresponding functionality for Byzantine consensus protocols, thus simplifying their design. We present a formal specification of a view synchronizer and its implementation under partial synchrony, which runs in bounded space despite tolerating message loss during asynchronous periods. We show that our synchronizer specification is strong enough to guarantee liveness for single-shot versions of several well-known Byzantine consensus protocols, including PBFT and HotStuff. We furthermore give precise latency bounds for these protocols when using our synchronizer. By factoring out the functionality of view synchronization we are able to specify and analyze the protocols in a uniform framework, which allows comparing them and highlights trade-offs.