A Correctness Proof for a Practical Byzantine-Fault-Tolerant Replication Algorithm

Abstract

We have developed a practical algorithm for state-machine replication [7,11] that tolerates Byzantine faults. The algorithm is described in [4]. It offers a strong safety property - it implements a linearizable [5] object such that all operations invoked on the object execute atomically despite Byzantine failures and concurrency. Unlike previous algorithms [11, 10, 6], ours works correctly in asynchronous systems like the Internet, and it incorporates important optimizations that enable it to outperform previous systems by more than on order of magnitude [4].