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arXiv · 2109.12454

Good-case and Bad-case Latency of Unauthenticated Byzantine Broadcast: A Complete Categorization

Ittai Abraham·Ling Ren·Zhuolun Xiang
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Abstract

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.

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Ittai Abraham, Ling Ren, Zhuolun Xiang. 2021-09-25. Good-case and Bad-case Latency of Unauthenticated Byzantine Broadcast: A Complete Categorization. https://arxiv.org/abs/2109.12454

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