I want my voice to be heard: IP over Voice-over-IP for unobservable censorship circumvention

Amir Houmansadr, Thomas Riedl, Nikita Borisov, Andrew Singer

Research output: Contribution to conferencePaperpeer-review

Abstract

Open communication over the Internet poses a serious threat to countries with repressive regimes, leading them to develop and deploy censorship mechanisms within their networks. Unfortunately, existing censorship circumvention systems face difficulties in providing unobservable communication with their clients; this highly limits their availability as censors can easily block access to circumvention systems that make observable communication patterns. Moreover, the lack of unobservability may pose serious threats to their users. Recent research takes various approaches to tackle this problem, however they introduce new challenges, and the provided unobservability is breakable. In this paper we propose an easy-to-deploy and unobservable censorship-resistant infrastructure, called FreeWave. FreeWave works by modulating a client's Internet traffic into acoustic signals that are carried over VoIP connections. Such VoIP connections are targeted to a server, the FreeWave server, that extracts the tunneled traffic and proxies them to the uncensored Internet. The use of actual VoIP connections, as opposed to traffic morphing, allows FreeWave to relay its VoIP connections through oblivious VoIP nodes (e.g., Skype supernodes), hence keeping the FreeWave server(s) unobservable and unblockable. In addition, the use of end-to-end encryption, which is supported/mandated by most VoIP providers like Skype, prevents censors from distinguishing FreeWave's VoIP connections from regular VoIP connections. To utilize a VoIP connection's throughput efficiently we design communications encoders tailored specifically for VoIP's lossy channel. We prototype FreeWave over Skype, the most popular VoIP system. We show that FreeWave is able to reliably achieve communication throughputs that are sufficient for web browsing, even when clients are far distanced from the FreeWave server. We also validate FreeWave's communication unobservability against traffic analysis and standard censorship techniques.

Original languageEnglish (US)
StatePublished - 2013
Event20th Annual Network and Distributed System Security Symposium, NDSS 2013 - San Diego, United States
Duration: Feb 24 2013Feb 27 2013

Conference

Conference20th Annual Network and Distributed System Security Symposium, NDSS 2013
Country/TerritoryUnited States
CitySan Diego
Period2/24/132/27/13

Keywords

  • Circumvention
  • Internet Censorship
  • VoIP

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Control and Systems Engineering
  • Safety, Risk, Reliability and Quality

Fingerprint

Dive into the research topics of 'I want my voice to be heard: IP over Voice-over-IP for unobservable censorship circumvention'. Together they form a unique fingerprint.

Cite this