overview - Infranet Background
software - source code and releases
papers - Infranet documents
talks - selected presentation slides
related articles - censorship circumvention in the news
related research - other censorship circumvention projects
people - who are we?
funding - who sponsors Infranet?


An increasing number of countries and companies routinely block or monitor access to parts of the Internet. To counteract these measures, we propose Infranet, a system that enables clients to surreptitiously retrieve sensitive content via cooperating Web servers distributed across the global Internet. These Infranet servers provide clients access to censored sites while continuing to host normal uncensored content. Infranet uses a tunnel protocol that provides a covert communication channel between its clients and servers, modulated over standard HTTP transactions that resemble innocuous Web browsing. In the upstream direction, Infranet clients send covert messages to Infranet servers by associating meaning to the sequence of HTTP requests being made. In the downstream direction, Infranet servers return content by hiding censored data in uncensored images using steganographic techniques. We describe the design, a prototype implementation, security properties, and performance of Infranet. Our security analysis shows that Infranet can successfully circumvent several sophisticated censoring techniques.

system architecture

Infranet consists of a requester and responder communicating over a covert tunnel. A requester, running on a user's computer, uses the tunnel to request censored content. Upon receiving the request, the responder, a standard public Web server running Infranet software, retrieves the sought content from the Web and returns it to the requester via the tunnel. In the upstream direction, the Infranet tunnel protocol modulates covert messages on standard HTTP requests for uncensored content. This is done using a confidentially negotiated function that maps URLs to message fragments, which compose requests for censored content. The requester and responder communicate via a channel with far greater bandwidth from the responder to the requester than vice versa. Because the responder serves many Infranet users' requests for hidden content, it can maintain the frequency distribution of hidden messages. A requester typically wants to send a message from this distribution.


Work on Infranet is proceeding quickly. To see the latest source code and releases, visit our project page at Sourceforge.


In the News


  • Infranet:Circumventing Web Censorship and Surveillance
  • Thwarting Web Censorship with Untrusted Messenger Discovery


    Faculty:  Hari Balakrishnan   David Karger  

    Graduate Students:  Nick Feamster   Magdalena Balazinska   Winston Wang   Greg Harfst  

    Related Articles

    Related Research


    Related Papers

    • I. Clarke, O. Sandbert, B. Wiley, and T. Hong. Freenet: A distributed anonymous information storage and retrieval system. In Proceedings of the Workshop on Design Issues in Anonymity and Unobservability, Berkeley, CA, July 2000.
    • R. Dingledine, M. Freedman, and D. Molnar. The Free Haven Project: Distributed anonymous storage service. In Proceedings of the Workshop on Design Issues in Anonymity and Unobservability, Berkeley, CA, July 2000.
    • D. Martin and A. Schulman. Deanonymizing users of the SafeWeb anonymizing service. In Proc. 11th USENIX Security Symposium, San Francisco, CA, August 2002.
    • M. Waldman and D. Mazières. Tangler: A censorship-resistant publishing system based on document entanglements. In Proceedings of the 8th ACM Conference on Computer and Communications Security, Philadelphia, PA, November 2001.
    • M. Waldman, A. Rubin, and L. Cranor. Publius: A robust, tamper-evident, censorship-resistant, web publishing system. In Proc. 9th USENIX Security Symposium, pages 59-72, Denver, CO, August 2000.

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