Reroute on Loop in Anonymous Peer-to-Peer Content Sharing Networks

Detecting and handling routing loops is a critical issue in the design of anonymous peer-to-peer content sharing networks (apCSNs). A principal requirement of such a scheme is that it should not leak any message forwarding information that can undermine the user anonymity of the resulting apCSN. A number of loop handling schemes have been developed in apCSNs such as Freenet and GNUnet. However, they all leak certain level of message forwarding information, which can be exploited to undermine or compromise the user anonymity. In this paper we develop a new loop handling scheme named Reroute-on-Loop (ROL) that will not leak any message forwarding information. Using the Thynix simulator developed by the Freenet project, we show that overall ROL only has minor performance impacts on message path lengths compared to the current loop handling scheme of Freenet on various network topologies, ranging from small-world topologies to random topologies. For example, the average routing path lengths of ROL are only increased by less than 1 hop compared to those with the current loop handling scheme of Freenet on small-world network topologies. Our performance studies confirm that ROL is a practical scheme, and can be deployed on Freenet and similar apCSN systems.