BeeGees: stayin' alive in chained BFT

TL;DR

BeeGees is a new chained BFT protocol that ensures decision-making with non-consecutive honest leaders, improving latency and robustness compared to existing protocols like HotStuff.

Contribution

BeeGees introduces a chained BFT protocol that guarantees liveness with non-consecutive honest leaders, addressing a key open problem in BFT consensus.

Findings

Reduces expected commit latency of HotStuff by a factor of three.

Reduces worst-case latency by a factor of seven.

Maintains quadratic and linear complexity with threshold signatures and SNARKs.

Abstract

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.