Federated Byzantine Agreement Systems (FBASs) are a fascinating new paradigm in the context of consensus protocols. Originally proposed for powering the Stellar payment network, FBASs can instantiate Byzantine quorum systems without requiring out-of-band agreement on a common set of validators; every node is free to decide for itself with whom it requires agreement. Sybil-resistant and yet energy-efficient consensus protocols can therefore be built upon FBASs, and the “decentrality” possible with the FBAS paradigm might be sufficient to reduce the use of environmentally unsustainable proof-of-work protocols. In this paper, we first demonstrate how the robustness of individual FBASs can be determined, by precisely determining their safety and liveness buffers and therefore enabling a comparison with threshold-based quorum systems. Using simulations and example node configuration strategies, we then empirically investigate the hypothesis that while FBASs can be bootstrapped in a bottom-up fashion from individual preferences, strategic considerations should additionally be applied by node operators in order to arrive at FBASs that are robust and amenable to monitoring. Finally, we investigate the reported “open-membership” property of FBASs. We observe that an often small group of nodes is exclusively relevant for determining liveness buffers and prove that membership in this top tier is conditional on the approval by current top tier nodes if maintaining safety is a core requirement.

联邦拜占庭协议系统 (FBAS) 是共识协议背景下的一个引人入胜的新范式。最初提议用于为 Stellar 支付网络提供动力，FBAS 可以实例化拜占庭仲裁系统，而无需在一组通用验证器上达成带外协议；每个节点都可以自由决定它需要与谁达成协议。因此，可以在 FBAS 上构建抗 Sybil 且节能的共识协议，并且 FBAS 范式可能实现的“去中心化”可能足以减少对环境不可持续的工作量证明协议的使用。在本文中，我们首先展示了如何确定单个 FBAS 的稳健性，方法是精确确定它们的安全性和活性缓冲区，从而与基于阈值的仲裁系统进行比较。使用模拟和示例节点配置策略，我们然后凭经验研究假设，虽然 FBAS 可以从个人偏好以自下而上的方式引导，但节点运营商应额外应用战略考虑，以得到稳健且适合的 FBAS到监控。最后，我们调查了报告的 FBAS 的“开放成员”属性。我们观察到通常一小群节点与确定活动缓冲区完全相关，并证明如果维护安全是核心要求，则该顶级节点的成员资格取决于当前顶级节点的批准。节点运营商应额外应用战略考虑，以实现稳健且易于监控的 FBAS。最后，我们调查了报告的 FBAS 的“开放成员”属性。我们观察到通常一小群节点与确定活动缓冲区完全相关，并证明如果维护安全是核心要求，则该顶级节点的成员资格取决于当前顶级节点的批准。节点运营商应额外应用战略考虑，以实现稳健且易于监控的 FBAS。最后，我们调查了报告的 FBAS 的“开放成员”属性。我们观察到通常一小群节点与确定活动缓冲区完全相关，并证明如果维护安全是核心要求，则该顶级节点的成员资格取决于当前顶级节点的批准。