We introduce Mysticeti-C, the first DAG-based Byzantine consensus protocol to achieve the lower bounds of latency of 3 message rounds. Since Mysticeti-C is built over DAGs it also achieves high resource efficiency and censorship resistance. Mysticeti-C achieves this latency improvement by avoiding explicit certification of the DAG blocks and by proposing a novel commit rule such that every block can be committed without delays, resulting in optimal latency in the steady state and under crash failures. We further extend Mysticeti-C to Mysticeti-FPC, which incorporates a fast commit path that achieves even lower latency for transferring assets. Unlike prior fast commit path protocols, Mysticeti-FPC minimizes the number of signatures and messages by weaving the fast path transactions into the DAG. This frees up resources, which subsequently result in better performance. We prove the safety and liveness in a Byzantine context. We evaluate both Mysticeti protocols and compare them with state-of-the-art consensus and fast path protocols to demonstrate their low latency and resource efficiency, as well as their more graceful degradation under crash failures. Mysticeti-C is the first Byzantine consensus protocol to achieve WAN latency of 0.5s for consensus commit while simultaneously maintaining state-of-the-art throughput of over 200k TPS. Finally, we report on integrating Mysticeti-C as the consensus protocol into the Sui blockchain, resulting in over 4x latency reduction.

翻译：我们提出了Mysticeti-C，这是首个基于有向无环图（DAG）的拜占庭容错共识协议，实现了3轮消息传递的延迟下界。由于Mysticeti-C构建于DAG之上，它同时实现了高资源效率和抗审查性。该协议通过避免对DAG区块进行显式认证，并设计了一种新颖的提交规则，使得每个区块都能无延迟提交，从而在稳态和崩溃故障下实现最优延迟。我们进一步将Mysticeti-C扩展为Mysticeti-FPC，该版本引入了快速提交路径，为资产转移提供更低的延迟。与现有的快速提交路径协议不同，Mysticeti-FPC通过将快速路径交易编织到DAG中，最小化了签名数量和消息传递。这释放了系统资源，从而提升了整体性能。我们在拜占庭容错场景下证明了协议的安全性与活性。通过评估两种Mysticeti协议并与最先进的共识协议及快速路径协议对比，我们展示了其在低延迟、资源效率方面的优势，以及在崩溃故障下更优雅的性能衰减特性。Mysticeti-C是首个在广域网环境下实现0.5秒共识提交延迟，同时保持超过20万TPS吞吐量的拜占庭容错共识协议。最后，我们报告了将Mysticeti-C作为共识协议集成至Sui区块链的实践，实现了超过4倍的延迟降低。