https://www.torproject.org/projects/obfsproxy-instructions.html.en https://gitweb.torproject.org/obfsproxy.git/tree/HEAD:/doc This is newly released by Tor project. It tries to obfuscate the traffic fingerprint associated with Tor traffic, and is intended for increasing membership concealment if used in addition to obfsproxy capable bridges. Eventually it will probably be a part of the regular Tor bridge system I imagine, but right now it is an add-on. Bridges help hide the fact that you use Tor because they are not publicly listed relays. You use bridges as the first hop on your circuit. However, Tor traffic still sticks out like a sore thumb. Obfsproxy tries to disguise your Tor traffic, and should substantially increase membership concealment. Now if only Tor would use two hop bridge chains, and add 'bridge guards' and bridge authorization. I hope they continue to focus on membership concealment.