Velisarios: Byzantine Fault-Tolerant Protocols Powered by Coq

Abstract

Our increasing dependence on complex and critical information infrastructures and the emerging threat of sophisticated attacks, ask for extended efforts to ensure the correctness and security of these systems. Byzantine fault-tolerant state-machine replication (BFT-SMR) provides a way to harden such systems. It ensures that they maintain correctness and availability in an application-agnostic way, provided that the replication protocol is correct and at least n − f out of n replicas survive arbitrary faults. This paper presents Velisarios, a logic-of-events based framework implemented in Coq, which we developed to implement and reason about BFT-SMR protocols. As a case study, we present the first machine-checked proof of a crucial safety property of an implementation of the area's reference protocol: PBFT.

Asphalion: trustworthy shielding against Byzantine faults

“…Comparison. As shown on the right, the average latency of our USIG-based implementation is lower than the one of the verified version of PBFT presented in [Rahli et al 2018]. Although Graphine-SGX incurs some overhead, our MinBFT implementation is faster because:…”

“…We now present HyLoE, a new hybrid variant of the Logic of Events (LoE) that was originally introduced in [Bickford 2009] to reason about crash fault tolerant protocols Rahli et al 2017;Schiper et al 2014], and later used to reason about cyber-physical systems [Anand and Knepper 2015]. LoE was then extended in [Rahli et al 2018] to handle BFT systems. We now extend LoE further to enable reasoning about hybrid fault models and hybrid protocols (which contain components with different failure assumptionsÐsome can be compromised, while others can only crash on failure), and explain the main differences with previous versions.…”

“…1a). As opposed to EventML, in Velisarios [Rahli et al 2018], an event is either of kind 1, or it corresponds to some arbitrary behavior, in which case no further information regarding this event is available/provided (kind 2Ðsee Fig. 1b).…”

“…(1) MinBFT uses less communication steps than PBFT; and (2) our MinBFT implementation uses less expensive crypto than in [Rahli et al 2018]. Our experiments use one client, f ∈ {1, 2, 3}, and the replicated service is a state machine that accumulates inputs using addition.…”

Verification of Threshold-Based Distributed Algorithms by Decomposition to Decidable Logics

“…We are not aware of works based on interactive theorem provers that verified protocols with complex thresholds as we do in this work (although doing so is of course possible). However, many works used interactive theorem provers to verify related protocols, e.g., [43,37,26,35,11,36] (the most related protocols use either n 2 or 2n 3 as the only thresholds, other protocols do not involve any thresholds). The downside of verification using interactive theorem provers is that it requires tremendous human efforts and skills.…”