When You Don't Trust Clients: Byzantine Proposer Fast Paxos

We derive a consensus protocol for a hybrid failure model. In this model, clients are Byzantine faulty and servers are crash faulty. We argue that this model is well suited to environments where the servers run within one administrative domain, and the clients run outside of this domain. Our consensus protocol, which is derived from crash Paxos, provides low latency for client requests, tolerates any number of (Byzantine) faulty clients, up to 1/3 (crash) faulty servers, and does not rely on computing costly signatures in the common case. It can be used to build state machine replication that provides a highly available service.