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Consensus using omega in asynchronous systems with unknown membership and degenerative Byzantine failures

Abstract:

We study consensus in asynchronous systems where membership is unknown, and where up to f degenerative Byzantine failures can happen. In our failure model a faulty process can have a Byzantine behavior (i.e., it deviates from its specification), and, furthermore, every faulty process will degenerate such that eventually it will have permanent physical or transmission failures. We present a simple algorithm that solves Consensus using the Omega failure detector and a new broadcast primitive called RFLOB in an asynchronous system with degenerative Byzantine failures, which is optimal with respect to failures because it works when f<n/3. RFLOB guarantees reliable, FIFO and local order broadcast in systems with Byzantine processes and unknown membership. Finally, we present an algorithm that implements an Omega failure detector with unknown membership and minimum connectivity (i.e., communication reliability, and synchrony properties) in a system with degenerative Byzantine failures.