Good-case and Bad-case Latency of Unauthenticated Byzantine Broadcast: A Complete Categorization
It addresses latency optimization in Byzantine fault-tolerant systems, offering foundational theoretical results for distributed computing.
This paper studies the good-case and bad-case latency of unauthenticated Byzantine broadcast, showing that n≥4f is the tight resilience threshold separating good-case 2 and 3 rounds in both asynchrony and synchrony, and provides matching bounds and protocols for bad-case latency in asynchronous BRB.
This paper studies the {\em good-case latency} of {\em unauthenticated} Byzantine fault-tolerant broadcast, which measures the time it takes for all non-faulty parties to commit given a non-faulty broadcaster. For both asynchrony and synchrony, we show that $n\geq 4f$ is the tight resilience threshold that separates good-case 2 rounds and 3 rounds. For asynchronous Byzantine reliable broadcast (BRB), we also investigate the {\em bad-case latency} for all non-faulty parties to commit when the broadcaster is faulty but some non-faulty party commits. We provide matching upper and lower bounds on the resilience threshold of bad-case latency for BRB protocols with optimal good-case latency of 2 rounds. In particular, we show 2 impossibility results and propose 4 asynchronous BRB protocols.