Byzantine Fault-Tolerant Atomic Multicast

Atomic multicast is an important building block in the architecture of scalable and highly available services. Atomic multicast reliably propagates and orders messages addressed to one or more groups of processes. Despite the large body of literature on atomic multicast, existing protocols target benign failures. This paper presents ByzCast, the first Byzantine Fault-Tolerant atomic multicast. Byzantine Fault Tolerance has become increasingly appealing as services can be deployed in inexpensive hardware (e.g., cloud environments) and new applications (e.g., blockchain) become more sensitive to malicious behavior. ByzCast has two important characteristics: it was designed to use existing BFT abstractions and it scales with the number of groups, for messages addressed to a single group. We discuss the design of ByzCast and how it can be optimized for particular workloads. Besides proposing a novel atomic multicast protocol, we extensively assess its performance experimentally.