A secure group membership protocol

A group membership protocol enables processes in a distributed system to agree on a group of processes that are currently operational. Membership protocols are a core component of many distributed systems and have proved to be fundamental for maintaining availability and consistency in distributed applications. In this paper we present a membership protocol for asynchronous distributed systems that tolerates the malicious corruption of group members. Our protocol ensures that correct members control and consistently observe changes to the group membership, provided that in each instance of the group membership, fewer than one-third of the members are corrupted or fail benignly. The protocol has many potential applications in secure systems and, in particular, is a central component of a toolkit for constructing secure and fault-tolerant distributed services that we have implemented.