Censorship Evasion with Unidentified Protocol Generation

We present the design and implementation of a novel approach to internet censorship evasion called Unidentified Protocol Generation (UPGen). UPGen automatically generates novel protocols for encrypted communication that are not easily recognizable as being UPGen protocols, but instead as some benign encrypted protocol unknown to the adversary. UPGen protocols are to be used to relay traffic to censored destinations via proxies, where each proxy can run a different UPGen-generated protocol. An adversary attempting to block at the protocol level but unable to identify UPGen protocols could cause significant collateral damage if it attempted to block all unidentified protocols. We conduct a security evaluation of UPGen employing state-of-the-art machine learning classifiers and find that it is infeasible to block UPGen protocols without also blocking existing encrypted protocols. We conduct small- and large-scale performance evaluations and find that UPGen protocols meet or exceed the performance of other common censorship evasion protocols.