In the field of distributed consensus and blockchains, the synchronous communication model assumes that all messages between honest parties are delayed at most by a known constant $\Delta$. Recent literature establishes that the longest-chain blockchain protocol is secure under the synchronous model. However, for a fixed mining rate, the security guarantees degrade with $\Delta$. We analyze the performance of the longest-chain protocol under the assumption that the communication delays are random, independent, and identically distributed. This communication model allows for distributions with unbounded support and is a strict generalization of the synchronous model. We provide safety and liveness guarantees with simple, explicit bounds on the failure probabilities. These bounds hold for infinite-horizon executions and decay exponentially with the security parameter. In particular, we show that the longest-chain protocol has good security guarantees when delays are sporadically large and possibly unbounded, which is reflective of real-world network conditions.
翻译:在分布式共识和链条领域,同步通信模式假定诚实方之间的所有信息最多被一个已知的常数$\Delta$推迟,最近的文献证明,在同步模式下,最长链条协议是安全的。但是,对于固定采矿率,安全保障以$\Delta$贬值。我们分析最长链协议的绩效,假设通信延误是随机的、独立的和相同的分布。这种通信模式允许无限制支持的传播,是同步模式的严格概括。我们提供安全和活性保障,对故障概率有简单、明确的界限。这些界限可维持无限的处决,并随着安全参数的急剧衰减。特别是,我们表明,当延迟是零星大且可能无限制的时,最长链协议有良好的安全保障,这反映了现实世界的网络条件。