Publications

Alea-BFT: Practical Asynchronous Byzantine Fault Tolerance

In Proc. of USENIX Symposium on Network Systems Design and Implementation (NSDI’24), Santa Clara, CA, 2024
Antunes D., Oliveira A., Breda A., Franco M., Moniz H., Rodrigues R.
Paper

Traditional Byzantine Fault Tolerance (BFT) state machine replication protocols assume a partial synchrony model, lead- ing to a design where a leader replica drives the protocol and is replaced after a timeout. Recently, we witnessed a surge of asynchronous BFT protocols, which use randomization to re- move the need for bounds on message delivery times, making them more resilient to adverse network conditions. However, existing research proposals still fall short of gaining practi- cal adoption, plausibly because they are not able to combine good performance with a simple design that can be readily understood and adopted. In this paper, we present Alea-BFT, a simple and highly efficient asynchronous BFT protocol, which is gaining practical adoption, namely in Ethereum dis- tributed validators. Alea-BFT brings the key design insight from classical protocols of concentrating part of the work on a single designated replica and incorporates this principle in a simple two-stage pipelined design, with an efficient broad- cast led by the designated replica, followed by an inexpensive binary agreement. The evaluation of our research prototype implementation and two real-world integrations in cryptocur- rency ecosystems shows excellent performance, improving on the fastest protocol (Dumbo-NG) in terms of latency and displaying good performance under faults.