Leveraging Internet Services to Evade Censorship

Abstract

Free and uncensored access to the Internet is an important right nowadays. Repressive regimes, however, prevent their citizens from freely using the Internet and utilize censorship to suppress unwanted content. To overcome such filtering, researchers introduced circumvention systems that avoid censorship by cloaking and redirecting the censored traffic through a legitimate channel. Sadly, this solution can raise alerts to censors, especially when it is mistakenly used. In this paper, we argue that relying on a single channel is not sufficient to evade censorship since the usage pattern of a circumvention system differs compared to a legitimate use of a service. To address this limitation of state-of-the-art systems, we introduce Camouflage, an approach to combine multiple non-blocked communication protocols and dynamically switch among these tunnels. Each protocol is only used for a limited amount of time and the Internet connection is transparently routed through instances of different censorship circumvention systems. We prototype Camouflage by using applications which are based on these protocols and also offer end-to-end encryption to prevent censors from distinguishing circumvention systems from regular services. We evaluate Camouflage in countries that impose censorship and demonstrate that our approach can successfully bypass existing censorship systems while remaining undetected.