StegoTorus: a camouflage proxy for the Tor anonymity system

Authors: Z. Weinberg, J. Wang, V. Yegneswaran, L. Briesemeister, S. Cheung, F. Wang, and D. Boneh

Internet censorship by governments is an increasingly common practice worldwide. Internet users and censors are locked in an arms race: as users find ways to evade censorship schemes, the censors develop countermeasures for the evasion tactics. One of the most popular and effective circumvention tools, Tor, must regularly adjust its network traffic signature to remain usable.

We present StegoTorus, a tool that comprehensively disguises Tor from protocol analysis. To foil analysis of packet contents, Tor's traffic is steganographed to resemble an innocuous cover protocol, such as HTTP. To foil analysis at the transport level, the Tor circuit is distributed over many shorter-lived connections with per-packet characteristics that mimic cover-protocol traffic. Our evaluation demonstrates that StegoTorus improves the resilience of Tor to fingerprinting attacks and delivers usable performance.

In proceedings of ACM CCS '12, pp. 109-120, 2012   [BIBTEX]