Low latency is one of the desired properties for partially synchronous Byzantine consensus protocols. Previous protocols have achieved consensus with just two communication steps either by reducing the bound on the number of faults the protocol can tolerate ($f \leq \frac{n-1}{5}$) or use of trusted hardware like Trusted Execution Environment or TEEs. In this paper, we propose a protocol called Fast B4B, in which the protocol achieves consensus in just two communication steps. Fast B4B can tolerate maximum number of faults a partial BFT consensus can tolerate ($f \leq \frac{n-1}{3}$). Furthermore, Fast B4B does not require the use of any trusted hardware. The trade-off for this achievement is that at most $f$ times some nodes may revert their blocks. We show that this reversion of a block will not compromise the safety of the protocol at all, yet it may incur a small amount of additional latency during view change.

翻译：低悬浮度是部分同步的拜占庭协商一致协议的理想属性之一。 以前的协议仅通过两个沟通步骤达成共识, 其方法是减少协议所能容忍的断层( f\leq\ frac{ n-1 ⁇ 5}$)的界限, 或使用信任的执行环境或TEE等信任的硬件。 在本文中, 我们提议了一个名为快速 B4B 的协议, 协议只需在两个沟通步骤中达成共识。 快速 B4B 可以容忍最大数目的断层。 部分 BFT 共识可以容忍 ( f\leq\ frac{ n-1 ⁇ 3}$ ) 。 此外, 快速 B4B 并不要求使用任何信任的硬件。 这一成就的权衡是, 在大多数情况下, 某些节点可以恢复他们的区块。 我们表明, 块的重新转换不会损害协议的安全性, 但是, 在变换时, 它可能会造成少量的额外延迟 。