http://i-hls.com/2016/01/67696/
http://news.mit.edu/2015/untraceable-anonymized-communication-guaranteed-1207
Researchers at the Computer Science and Artificial Intelligence Laboratory (CSAIL) at the Massachusetts Institute of Technology (MIT) have developed a new online text messaging protocol that is far more secure and harder to trace than current alternatives, including the Tor anonymity network.
First, in cooperation with scientists from the Qatar Computing Research Institute (QCRI), they successfully exploited a security vulnerability affecting the Tor networks that made it possible to identify hidden servers with up to 88% accuracy. They accomplished this by observing patterns in the number of packets passing through Tor nodes. They managed to determine with 99% accuracy the type of communication taking place: whether it was regular web browsing, an introduction point (that gives users access to hidden a website), or a rendezvous point (that gives a second user access to the same hidden website at the same time as the first).