The Dolev-Reischuk bound says that any deterministic Byzantine consensus protocol has (at least) quadratic communication complexity in the worst case. While it has been shown that the bound is tight in synchronous environments, it is still unknown whether a consensus protocol with quadratic communication complexity can be obtained in partial synchrony. Until now, the most efficient known solutions for Byzantine consensus in partially synchronous settings had cubic communication complexity (e.g., HotStuff, binary DBFT). This paper closes the existing gap by introducing SQuad, a partially synchronous Byzantine consensus protocol with quadratic worst-case communication complexity. In addition, SQuad is optimally-resilient and achieves linear worst-case latency complexity. The key technical contribution underlying SQuad lies in the way we solve view synchronization, the problem of bringing all correct processes to the same view with a correct leader for sufficiently long. Concretely, we present RareSync, a view synchronization protocol with quadratic communication complexity and linear latency complexity, which we utilize in order to obtain SQuad.

翻译：Dolev-Reischuk 绑定的Dolev-Reischuk 表示, 任何确定性的Byzantine 协商一致协议在最坏的情况下( 至少) 具有二次通信复杂性。 虽然已经显示, 捆绑在同步环境中十分紧凑, 但是仍然不清楚的是, 一个带有二次通信复杂性的协商一致协议能否以部分同步的方式获得。 直到现在, 在部分同步环境中, 最高效的 Byzantine 共识协议已知的比尚庭特( HotStuff, binary DBFT) 具有立方通信复杂性。 本文通过引入 SQuad( Squad, 一种部分同步的Byzantine 协商一致协议) 来弥补现有的差距。 此外, Squad 是最佳的弹性, 并实现了线性最坏的悬浮度复杂性 。 Squad 背后的关键技术贡献在于我们如何看待同步, 将所有正确的进程都带到同一观点中, 并有一个足够长的正确领导人。 。 具体地说, 我们介绍 RareSync, 一种与四重通信复杂性和线性悬浮性协议的视图同步协议, 我们利用它来获取 。