发表机构
University of Illinois Chicago（伊利诺伊大学芝加哥分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一种拜占庭容错的因果排序算法，通过发送权限不变量和隔离缓冲区乐观模型，实现O(1)消息空间开销，并保证系统活性与弱因果安全，平衡了吞吐量和资源开销。
AI 中文摘要
因果消息排序为分布式应用提供了必要的语义，然而在存在拜占庭故障的异步系统中确保因果排序，带来了根本性的理论和实践挑战。先前的研究表明，在这些条件下，不使用密码学，算法无法同时保证强安全性和活性。现有的拜占庭容错解决方案要么做出同步性假设，要么遭受$O(n)$的消息空间开销和$O(n^2)$的消息复杂度（其中$n$是系统中的进程数），或者使用密码学，但可能无法保证强安全性。在本文中，我们提出了一种新颖的拜占庭容错因果排序算法，该算法为点对点消息实现了最优的$O(1)$应用消息空间开销。我们的方法使用发送权限发送（SPS）不变量和用于内存管理架构的隔离缓冲区乐观模型。为了规避拜占庭状态固定和队头阻塞攻击，我们不使用统一的因果缓冲区，而是使用配备事件驱动的级联空间驱逐的隔离的、每对等方队列。我们正式证明，我们的算法保证了系统范围的活性，并满足一种弱化的因果安全抽象，称为拥塞松弛因果传递。在该模型下，除非极端网络延迟或拜占庭扣留攻击超过可量化的本地缓冲区容量，迫使乐观队列驱逐，否则所有诚实到诚实的通信都严格保留弱因果安全性。这一形式化保证成功地在因果排序与高吞吐量、恒定消息空间开销、低计算开销和严格有界的本地空间之间取得了平衡。
英文摘要
Causal message ordering provides essential semantics for distributed applications, yet ensuring it within an asynchronous system subject to Byzantine failures presents fundamental theoretical and practical challenges. Prior research establishes that algorithms cannot guarantee both strong safety and liveness without using cryptography under these conditions. Existing Byzantine-tolerant solutions make synchrony assumptions or suffer from $O(n)$ message space overheads and $O(n^2)$ message complexity, where $n$ is the number of processes in the system, or use cryptography, but may not guarantee strong safety. In this paper, we present a novel Byzantine-tolerant causal ordering algorithm that achieves an optimal $O(1)$ application message space overhead for point-to-point messages. Our approach uses a Sender Permission to Send (SPS) invariant and an \textit{Isolated-Buffer Optimistic Model} for the memory management architecture. To circumvent Byzantine state-pinning and head-of-line blocking attacks, instead of unified causal buffers, we use isolated, per-peer queues equipped with event-driven \textit{Cascading Space Evictions}. We formally prove that our algorithm guarantees system-wide liveness and satisfies a weakened causal safety abstraction called \textit{Congestion-Relaxed Causal Delivery}. Under this model, weak causal safety is strictly preserved for all honest-to-honest communications unless extreme network latency or Byzantine withholding attacks exceed quantifiable local buffer capacities, forcing optimistic queue evictions. This formal guarantee successfully balances causal ordering with high throughput, constant message space overhead, low computational overhead, and strictly bounded local space.
