Internet censorship poses a significant threat to the rights of individuals to access information and communicate without interference. Such censorship typically prohibits accessing only certain online content or platforms. As a result, it has become popular to evade censorship using encrypted connections to proxies located outside the censor’s view. However, proxied traffic has been shown to exhibit characteristic packet size and timing patterns, which are observable to the censor despite encryption. Such identifying patterns may be eliminated via traffic shaping, where packet sizes and times are intentionally modified by the sender. We propose that traffic shaping be accomplished in proxy systems using a modular traffic shaper and present an API for such a module. Modularization will allow easier experimentation as well as reuse of shaping policies across different proxy systems. We implement a proof-of-concept traffic-shaping module in the Proteus system and conduct experiments showing that it can express a variety of shaping policies.
@inproceedings{tsapi-wpes2026,
title = {Modular Traffic Shaping for Censorship Evasion},
author = {Johnson, Aaron and Jansen, Rob},
booktitle = {Workshop on Privacy in the Electronic Society},
year = {2026},
doi = {10.1145/3847192.3847369},
}