Performance Analysis of Anonymous Communication Channels Provided by Tor

Providing anonymity for end-users on the Internet is a very challenging and difficult task. There are currently only a few systems that are of practical relevance for the provision of low-latency anonymity. One of the most important to mention is the Tor network that is based on onion routing. Practical usage of the system often leads to delays which are not tolerated by the average end-user. This, in return, discourages many of them from the use of such systems and hence indirectly lowers the protection of remaining users due to a smaller user base. In this paper we show to which extend overloaded nodes and links, as well as geographical diversity of nodes have an influence on the general performance of Tor communication channels. After that, we propose new methods of path selection for performance-improved onion routing which are based on actively measured latencies and estimated available capacities using passive observations of link- wise throughput.