Скачать или смотреть Defense Talk by Tuan Tran

Byzantine fault tolerant state machine replication (BFT) is an approach to building highly-available services that can tolerate any type of failures, including bugs in the software and adversarial replicas. Recent adoption of BFT protocols in blockchain systems has made what used to be primarily theoretical research practical at large scale, and has led to renewed interest into these protocols. Both classical (permissioned) BFT protocols and blockchain (permissionless) protocols share one common characteristic in that they are designed to mask faults, i.e., they ignore faulty replicas and rely on correct replicas to keep the system functional. However, the existence of Byzantine faults in these systems is a real concern, and the failure to detect them can lead to violations of the correctness properties that BFT systems provide. For permissioned BFT systems, where strong consistency is prioritized in exchanged for weak availability, and the number of replicas as well as the fault tolerance threshold are known and fixed, undetected faulty replicas can accumulate over time and eventually surpass the predefined fault threshold, after which the system can no longer guarantee availability (and possibly consistency). For blockchain systems, where strong availability is prioritized in exchanged for weak consistency, an adversary can cause inconsistencies between a replica and the rest of the network. Therefore, these two classes of BFT systems present unique challenges in how fault detection can be used to strengthen their correctness properties.

May 6, 2024 at UC Santa Cruz