To achieve higher efficiency over their unstructured counterparts, structured peer-to-peer systems hold each node responsible for serving a specified set of keys and correctly routing lookups. Unfortunately, malicious participants can abuse these responsibilities to deny access to a set of keys or misroute lookups. We look to address both of these problems through replica placement. Using Chord as an example, we present an equally-spaced replication scheme and prove that it can be tuned to produce any desired number of disjoint routes. To be specific, we prove that d disjoint routes can be produced by placing 2d−1 replicas around a fully populated Chord ring in an equally-spaced fashion. In this situation, we also prove that there exists a route to at least one replica, which contains only uncompromised nodes, even if an attacker controls more than a quarter of the contiguous identifier space in the system. Simulation experiments demonstrate that this scheme performs better than...
Cyrus Harvesf, Douglas M. Blough