Professor Gregory Chockler

Professor in Computer Science
PhD (Hebrew University of Jerusalem)
+44 (0)1483 682651
06 BB 02


Areas of specialism

Trustworthy and secure distributed systems; Large-scale distributed systems and clouds; Blockchain consensus


Research interests


Postgraduate research supervision


Manuel Bravo, Gregory Chockler, Alexey Gotsman (2022)Making Byzantine consensus live, In: Distributed Computing35pp. 503-532 Springer

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 abstraction 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.