Kudzu: Fast and Simple High-Throughput BFT

TL;DR

Kudzu is a high-throughput Byzantine fault-tolerant broadcast protocol that achieves fast finality with a simple design, utilizing erasure codes and balanced bandwidth use to outperform existing solutions.

Contribution

Kudzu introduces a simple, high-throughput BFT protocol with a fast two-round finality and balanced bandwidth utilization, avoiding complex mechanisms like view changes.

Findings

Achieves finality in two rounds under certain fault conditions

Maintains high throughput with balanced bandwidth use

Avoids complex mechanisms like view changes and speculative execution

Abstract

We present Kudzu, a high-throughput atomic broadcast protocol with an integrated fast path. Our contribution is based on the combination of two lines of work. Firstly, our protocol achieves finality in just two rounds of communication if all but $p$ out of $n = 3f + 2p + 1$ participating replicas behave correctly, where $f$ is the number of Byzantine faults that are tolerated. Due to the seamless integration of the fast path, even in the presence of more than $p$ faults, our protocol maintains state-of-the-art characteristics. Secondly, our protocol utilizes the bandwidth of participating replicas in a balanced way, alleviating the bottleneck at the leader, and thus enabling high throughput. This is achieved by disseminating blocks using erasure codes. Despite combining a novel set of advantages, Kudzu is remarkably simple: intricacies such as progress certificates, complex view changes, and speculative execution are avoided.