Message in a Bottle: Sailing Past Censorship


Luca Invernizzi, Christopher Kruegel, Giovanni Vigna


Proceedings of the 29th Annual Computer Security Applications Conference (ACSAC), December 2015


Exploiting recent advances in monitoring technology and the drop of its costs, authoritarian and oppressive regimes are tightening the grip around the virtual lives of their citizens. Meanwhile, the dissidents, oppressed by these regimes, are organizing online, cloaking their activity with anti-censorship systems that typically consist of a network of anonymizing proxies. The censors have become well aware of this, and they are systematically finding and blocking all the entry points to these networks. So far, they have been quite successful. We believe that, to achieve resilience to blocking, anti-censorship systems must abandon the idea of having a limited number of entry points. Instead, they should establish first contact in an online location arbitrarily chosen by each of their users. To explore this idea, we have developed Message In A Bottle, a protocol where any blog post becomes a potential “drop point” for hidden messages. We have developed and released a proof-of-concept application of our system, and demonstrated its feasibility. To block this system, censors are left with a needle-in-a-haystack problem: Unable to identify what bears hidden messages, they must block everything, effectively disconnecting their own network from a large part of the Internet. This, hopefully, is a cost too high to bear.


  title     = {{Message in a Bottle: Sailing Past Censorship}},
  author    = {Invernizzi, Luca and Kruegel, Christopher and Vigna, Giovanni},
  booktitle = {Proceedings of the 29th Annual Computer Security Applications Conference (ACSAC)},
  year      = {2013},
  address   = {New York, NY, USA},
  doi       = {10.1145/2523649.2523654},
  isbn      = {978-1-4503-2015-3},
  pages     = {39--48},
  publisher = {ACM},
  url       = {}