Anonymity in Structured Peer-to-Peer Networks

Existing peer-to-peer systems that aim to provide anonymity to its users are based on networks with unstructured or loosely-structured routing algorithms. Structured routing offers performance and robustness guarantees that these systems are unable to achieve. We therefore investigate adding anonymity support to structured peer-to-peer networks. We apply an entropy-based anonymity metric to Chord [SMK01] and use this metric to quantify the improvements in anonymity afforded by several possible extensions. We identify particular properties of Chord that have the strongest effect on anonymity and propose a routing extension that allows a general trade-off between anonymity and performance. Our results should be applicable to other structured peer-to-peer systems.