Path Selection Metrics for Performance-Improved Onion Routing

Providing anonymity for users on the Internet is a very challenging and difficult task. Currently there are only a few systems that are of practical relevance for the provision of low-latency anonymity. One of the most important to mention is Tor which is based on onion routing. Practical client usage of Tor often leads to delays that are not tolerated by the average end-user, which, in return, discourages many of them from using the system. In this paper we propose new methods of path selection that allow performance-improved onion routing. These are based on actively measured latencies and estimations of available link-wise capacities using passive observations of throughput. We evaluate the proposed methods in the public Tor network and present a practical approach to empirically analyze the strength of anonymity certain methods of path selection provide in comparison to each other.