论文标题
同时诚实的老虎机领导者的一致性区块链的一致性
Consistency of Proof-of-Stake Blockchains with Concurrent Honest Slot Leaders
论文作者
论文摘要
我们通过首次与并发诚实的领导者的回合产生的积极效果，提高了最终共识证明（POS）区块链协议的基本安全门槛。 当前的安全性分析将一致性降低到基于抽象的，基于圆形的块创建过程的动态，该过程由与一轮相关的三个事件确定：（i）事件$ a $：至少一个对抗性领导者（ii）事件$ s $：一个诚实的领导者，以及（iii）事件$ m $：多，但诚实，领导者。我们提出了一个渐近最佳的一致性分析，假设诚实的回合比对抗性回合更有可能（即$ \ pr [s] + \ pr [m]> \ pr [a] $）;此阈值是最佳的。这是文献中的第一个，可以应用于简单的同步通信以及与有限延迟的通信。 在所有现有的一致性分析中，事件$ m $受到处罚或中立治疗。具体而言，Ouroboros Praos（Eurocrypt 2018）和Genesis（CCS 2018）中的一致性分析假设$ \ pr [s] - \ pr [m]> \ pr [a] $;昏昏欲睡的共识分析（Asiacrypt 2017）和白雪公主（Fin。Crypto2019）假定$ \ pr [s]> \ pr [a] $。此外，当$ \ pr [s] <\ pr [a] $时，所有现有的分析都会完全分解。这些阈值决定了诚实多数，网络延迟和一致性错误之间的关键权衡。 我们的新结果可以直接应用于改善现有协议的安全保证。我们还提供了一种有效的算法来在同步设置中明确计算这些误差概率。此外，我们通过分析$ s $很少的设置，即使允许$ \ pr [s] = 0 $，在诚实玩家采用一致的链选择规则的情况下进行补充。
We improve the fundamental security threshold of eventual consensus Proof-of-Stake (PoS) blockchain protocols under the longest-chain rule by showing, for the first time, the positive effect of rounds with concurrent honest leaders. Current security analyses reduce consistency to the dynamics of an abstract, round-based block creation process that is determined by three events associated with a round: (i) event $A$: at least one adversarial leader, (ii) event $S$: a single honest leader, and (iii) event $M$: multiple, but honest, leaders. We present an asymptotically optimal consistency analysis assuming that an honest round is more likely than an adversarial round (i.e., $\Pr[S] + \Pr[M] > \Pr[A]$); this threshold is optimal. This is a first in the literature and can be applied to both the simple synchronous communication as well as communication with bounded delays. In all existing consistency analyses, event $M$ is either penalized or treated neutrally. Specifically, the consistency analyses in Ouroboros Praos (Eurocrypt 2018) and Genesis (CCS 2018) assume that $\Pr[S] - \Pr[M] > \Pr[A]$; the analyses in Sleepy Consensus (Asiacrypt 2017) and Snow White (Fin. Crypto 2019) assume that $\Pr[S] > \Pr[A]$. Moreover, all existing analyses completely break down when $\Pr[S] < \Pr[A]$. These thresholds determine the critical trade-off between the honest majority, network delays, and consistency error. Our new results can be directly applied to improve the security guarantees of the existing protocols. We also provide an efficient algorithm to explicitly calculate these error probabilities in the synchronous setting. Furthermore, we complement these results by analyzing the setting where $S$ is rare, even allowing $\Pr[S] = 0$, under the added assumption that honest players adopt a consistent chain selection rule.
