Towards Unobservable Censorship Circumvention

Amir Houmansadr


The recent advances in censorship technologies allow repressive regimes to effectively recognize and block the traffic generated by censorship circumvention systems. This calls for an essential requirements for today’s circumvention systems, which is unobservability. A recent trend of circumvention systems aims for unobservability by imitating popular Internet protocols like Skype and HTTP. We demonstrate that these systems completely fail to achieve unobservability. We show that even a weak censor can easily distinguish their traffic from the imitated protocols.

In the second part of my talk I introduce an alternative approach towards unobservable circumvention, which we call it hide-within. As opposed to imitating protocols a hide-within circumvention runs the target protocol and tunnels the circumvention traffic through the genuine run of that protocol. I present FreeWave, the first hide-within system, which embeds circumvention traffic into VoIP connections by modulating data into audio signals. I conclude with challenges and future directions.

Bio: Amir Houmansadr is a postdoctoral researcher at the University of Texas at Austin. Amir’s research revolves around various network security and privacy problems, including censorship circumvention, network traffic analysis, and anonymous communications. Amir received his Ph.D. from the University of Illinois at Urbana-Champaign in 2012.

Time and Place

Thursday, May 23, 2013, 4:15pm
Gates 498