Computer scientists have released a tool that disguises communications sent through the Tor anonymity service as Skype video calls, a cloak that’s intended to prevent repressive governments from blocking the anonymous traffic.
SkypeMorph, as the application is called, is designed to remedy a fundamental limitation of Tor: While the communications are cryptographically secured, unique characteristics of their individual data packets make them easy to identify as they travel over the networks. In the past, for example, the cryptographic key exchange was different in Tor transactions and the certificates used were typically valid for only a matter of hours, compared with as long as a year or two for certificates used by most Web servers. These fingerprints made it possible for government censors in Iran, China, and elsewhere to block data traveling over Tor while leaving the rest of the country’s communications intact.
Tor developers have remedied those shortcomings, but other unique signatures still exist. The idea behind SkypeMorph is to camouflage Tor communications so they blend in as traffic that government censors are reluctant to restrict.
“The goal is to make the traffic look like some other protocol that they are not willing to block,” Ian Goldberg, a professor at the Cheriton School of Computer Science at the University of Waterloo, told Ars. “They could just shut off the Internet, of course, like Egypt did for a few days a year or so ago, but that, of course, would be extremely unpopular to their own people that are wondering why can’t see pictures of cute cats.”