The Tor Onion Router privacy software is currently blocked by the Great Firewall of China. Investigation done by the Torproject indicates that China is using deep packet inspection to enumerate Tor connections going to and from the country using Tors own cipher list (bug #4744). This inspection reveals both bridge and router connections. China then makes a follow-up connection to bridges when they are detected to determine that they actually are bridges. Tor bridges are blocked immediately after this test. Roger Dingledine and Jacob Appelbaum gave some details on this at 28c3.
The number of direct Tor users in China flat-lined long ago. The number of bridge users in China is currently dropping dramatically as seen on this graph:...Read the rest of this entry »








