de-Tor-iorate Anonymity

Presented at DEF CON 16 (2008), Aug. 8, 2008, 7 p.m. (20 minutes)

Feel safe and comfortable browsing the Internet with impunity because you are using Tor? Feel safe no more! We present an attack on the Tor network that means that the bad guys could find out where you are going on the Internet while using Tor. This presentation goes over the design decisions that have made this attack possible, as well as show results from a Tor network that reveals the paths that data travels when using Tor. This method can make using the Tor network no more secure than using a simple open web proxy. We go over the attack in detail, as well as possible solutions for future versions of Tor.


  • Christian Grothoff
    Christian Grothoff is an assistant professor of computer science at the University of Denver. He earned his PhD in computer science from UCLA in expressive type systems for object-oriented languages. His research interests include compilers, programming languages, software engineering, networking and security. He also is the primary author and maintainer of GNUnet, GNU's peer-to-peer framework.
  • Nathan Evans - Ph.D Student, University of Denver
    Nathan Evans is a Ph.D student and the University of Denver working in the areas of security, privacy, anonymity, and performance in P2P networks. While he seems to be running around trying to break all the networks his intentions are to improve the current state of affairs wrt security. Previous work includes Routing in the Dark: Pitch Black (presented at Defcon 15) and work on evaluating various P2P systems published in the German magazine IX.


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