A Symmetric Replication Scheme for Increased Security and Performance in Structured Overlay Networks
Ali Ghodsi, Luc Onana Alima, Seif Haridi · 2004
Abstract. Existing structured peer-to-peer systems heavily rely on replication as a means to provide fault-tolerance. Many systems use the so-called successor-list scheme for replication. We argue that this scheme has grave limitations. First, these systems are vulnerable to, what we call, Mendacity attacks, where a malicious peer can lie about other peers to gain full control over all replicas of an item. Sec-ond, the successor-list scheme prevents the peers from doing concurrent-requests to replicas of an item. We present, and provide full algorithmic speci¯cation for, a generic replication scheme called symmetric replication. The scheme is applicable to all existing structured peer-to-peer systems. In contrast to the successor-list scheme, our scheme makes replicas independent of each other, preventing Men-dacity attacks while enabling concurrent requests. Concurrent requests can be used for increasing the security by using voting or consensus algorithms to en-sure the correctness of replicas. Moreover, concurrent requests can be used for load-balancing of requests, and to add locality awareness. Finally, to maintain the replication factor, the successor-list scheme uses a complex algorithm that involves all peers replicating a departing peer. In contrast, our symmetric repli-cation scheme only involves two peers to restore the replication factor and thus avoids such complex algorithms. 1