An Improved Tor Circuit-Building Protocol

Tor is the second generation onion router, supporting the anonymous transport of TCP streams over the Internet. Its low latency makes it very suitable for common Internet communication applications. So Tor has become the most successful public anonymity communication service in the Internet. In this paper, we investigate Tor current circuit-building protocol. We found some performance and user experience deficiencies in this protocol. Based on the investigation we propose improved circuit-building protocol. The protocol includes two phases: user-selectable relay node selection and circuit construction. In the new protocol, we propose three new algorithms: user-selectable relay node selection algorithm, fast circuit constructing algorithm and backup circuit algorithm. In addition we also present an evaluation to the new protocol in terms of user experience, performance and anonymity. Through our evaluation, we think with our improved circuit-building protocol, we can provide better user experience, better performance and the same anonymity with current circuit-building protocol to Tor users.