[Whonix-devel] private and obfuscated bridges not so good for hiding Tor

[<adr...@ri...>]

(This is a general issue. Not an issue caused by Whonix.)

Using private and obfuscated bridges alone doesn't provide strong guarantees of hiding your the fact you are using Tor from your ISP. Quote [1] (w [2]) Jacob Appelbaum:

> "Some pluggable transports may seek to obfuscate traffic or to morph it. However, they do not claim to hide that you are using Tor in all cases but rather in very specific cases. An example threat model includes a DPI device with limited time to make a classification choice - so the hiding is very specific to functionality and generally does not take into account endless data retention with retroactive policing."

I agree. It's an arms race. The goal of the user is to hide the fact, being a Tor user. The goal of the adversary is to find out who is using Tor by passively logging all (or reasonable portions) of traffic. Even if a private and obfuscated (pluggable transports) bridge is trustworthy and there are at the moment no known weaknesses in the traffic obfuscation, time plays for of the adversary. Once a weakness has been found, all traffic can be retrospectively classified as Tor traffic. Updated and improved pluggable transports enable users again with censorship circumvention, users already known to have used Tor however, will still be known.

[1] [https://mailman.boum.org/pipermail/tails-dev/2013-April/002950.html](https://mailman.boum.org/pipermail/tails-dev/2013-April/002950.html)  
[2] [http://www.webcitation.org/6G67ltL45](http://www.webcitation.org/6G67ltL45)

URL: http://sourceforge.net/p/whonix/featureblog/2013/04/private-and-obfuscated-bridges-not-so-good-for-hiding-tor/