Efficient Update Diffusion in Byzantine Environments

We present a protocol for diffusion of updates among replicas in a distributed system where up to b replicas may suffer Byzantine failures. Our algorithm ensures that no correct replica accepts spurious updates introduced by faulty replicas, by requiring that a replica accepts an update only after receiving it from at least b + 1 distinct replicas (or directly from the update source). Our algorithm diffuses updates more efficiently than previous such algorithms and, by exploiting additional information available in some practical settings, sometimes more efficiently than known lower bounds predict.