Towards "Dark" Social Networking Services
Thorsten Strufe
Technical University of Darmstadt
Wednesday, March 27, 2013
11:00 a.m., ICSI Lecture Hall
Means for comprehensive identity concealment are a basic prerequisite for freedom of speech: only writing anonymously, or under a pseudonym, and without the danger of being identified and sought out in the physical world enables individuals to state their opinions not only under oppressive regimes, but in "the free world" as well, avoiding trace and prosecution, or even just ridicule. TOR has been proposed to conceal network addresses. Several attacks, however, have been devised, it is prone to filtering, and it requires trust into the exit nodes. Darknets, for that matter, conceal network identities by restricting connections to devices of individuals with a mutual trust relationship in the real world. Freenet is the only fully implemented and deployed Darknet. Restricting the topology to the social graph, Freenet employs graph embedding to approximate a structured topology and terminally allow for some greedy-like routing.
Analyzing Freenet, we came up with ad-hoc attacks that break both embedding and routing. We propose an adapted embedding that is resistant, at least to all attacks known to us. Analyzing the routing we additionally devised a novel Darknet model and prove that Freenet routing can not be successful in an expected polylog number of routing steps. We hence propose an adapted routing that is slightly less performant in some cases, yet achieves an expected polylog routing length. We finally examine an entirely different class of embeddings. They achieve perfect greedy embeddings, at the cost of an again slightly higher weakness to attacks and slight loss of information about the social neighborhood of users. In the talk I'll give a brief overview of our model, proofs, and proposed solutions towards censorship resistant communication.