Modern chained Byzantine Fault Tolerant (BFT) systems leverage a combination of pipelining and leader rotation to obtain both efficiency and fairness. These protocols, however, require a sequence of three or four consecutive honest leaders to commit operations. Therefore, even simple leader failures such as crashes can weaken liveness both theoretically and practically. Obtaining a chained BFT protocol that reaches decisions even if the sequence of honest leaders is non-consecutive, remains an open question. To resolve this question we present BeeGees, a novel chained BFT protocol that successfully commits blocks even with non-consecutive honest leaders. It does this while also maintaining quadratic word complexity with threshold signatures, linear word complexity with SNARKs, and responsiveness between consecutive honest leaders. BeeGees reduces the expected commit latency of HotStuff by a factor of three under failures, and the worst-case latency by a factor of seven.

翻译：摘要：现代链式拜占庭容错系统结合流水线与领导者轮换机制，实现了高效性与公平性。然而，这些协议需要连续三至四位诚实领导者才能提交操作。因此，即便是崩溃这类简单的领导者故障，也会在理论与实践中损害活性。如何设计一种即便面对非连续诚实领导者序列仍能达成决策的链式BFT协议，至今仍是未解难题。为解决此问题，我们提出BeeGees——一种新型链式BFT协议，能够在非连续诚实领导者情况下成功提交区块。该协议在保持阈值签名下二次字复杂度、SNARK下线性字复杂度以及连续诚实领导者间响应性的同时，将HotStuff在故障下的预期提交延迟降低至三分之一，最坏情况延迟降低至七分之一。