Design Improvement for Tor against Low-Cost Traffic Attack and Low-Resource Routing Attack

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 design weaknesses. An adversary can use these weaknesses to attack Tor network such as low-cost traffic attack, low-resource routing attack and so on. Based on the investigation we propose tuning mechanisms to overcome the above-mentioned problems. The tuning mechanisms include establishing evaluation system and optimizing Tor node store and output mode. In addition we also present a theoretical analysis to the tuning mechanisms in terms of anonymity and performance. Through our theoretical analysis, we think with our tuning mechanisms, we can promote Tor network anonymity dramatically, and promote Tor network overall performance to the extent.