Path tracing in TOR networks

Internet based communications methods use channels which cross many nodes in their routes between source and destination. The user often has little or no control in the routing process and may be concerned that the medium is insecure. To combat this, privacy preserving networks have been developed in an attempt to allow secure, private internet-based communication. Whilst these networks employ high levels of encryption between nodes, it is possible to track a users data by correlating input and output streams. This paper addresses the implementation of the algorithmfirst proposed by Danezis for determining the exit node of data injected into a privacy preserving network, such as Tor. The algorithm is discussed along with some modifications and assumptions necessary for implementation. Results gained from applying the algorithm to data from a real Tor network are presented and discussed.