PeerReview: Practical Accountability for Distributed Systems

The authors describe PeerReview, a system that provides accountability in distributed systems. PeerReview ensures that Byzantine faults whose effects are observed by a correct node are eventually detected and irrefutably linked to a faulty node. At the same time, PeerReview ensures that a correct node can always defend itself against false accusations. These guarantees are particularly important for systems that span multiple administrative domains, which may not trust each other. PeerReview works by maintaining a secure record of the messages sent and received by each node. The record is used to automatically detect when a node's behavior deviates from that of a given reference implementation, thus exposing faulty nodes.