Hacking anonymity and TOR

TOR is endorsed by the Electronic Frontier Foundation (EFF) and is designed for individuals to circumvent Web censorship in countries such as China, however, the network could be used by criminals or even terrorists. Andrew Christensen, a Danish researcher at PacketStormSecurity.org, decided to see if he could determine who was using TOR by breaking the network's supposed anonymity. His theories about how he might do this appeared last spring in a paper entitled Peeling the Onion (coauthored with Dan Fearch of ScanNet). Now, Christensen's published workable code is in a paper called Practical Onion Hacking...
So are criminals using anonymizing services to arrange crimes over the Internet? Yes, but security experts agree that criminals (and possibly terrorists) have their own methods of anonymizing their Web traffic. So far, the bad guys aren't really using the TOR network...

Read the review and the papers:
1- Peeling the Onion
2- Practical Onion Hacking