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Update design documentation about network fingerprinting

Discussion:

[Tails-dev] todo/network_fingerprint

Original:

https://tails.boum.org/contribute/design/#index4h1

3.11 Fingerprint

Tails tries to make it as difficult as possible to distinguish Tails users from other Tor users.

Iceweasel is configured to match the fingerprint of the Tor Browser Bundle and the known differences, if any, are listed in the known issues page.

However the fact that different extensions are installed in Tails and in the TBB surely allows more sophisticated attacks that usual fingerprint as returned by tools such as https://panopticlick.eff.org/ and http://ip-check.info/. For example, the fact that Adblock is removing ads could be analysed.

From the point of view of the local network administrator, Tails is almost exclusively generating Tor activity and that is probably quite different from other TBB users. We believe this would be hard to avoid. Other possible fingerprint issues on the LAN or ISP exist but we believe they would be harder to detect. See the discussion on fingerprinting in the Time sync design document and the fingerprint documentation.

Proposed change:

Fingerprint

Tails tries to make it as difficult as possible to distinguish Tails users from other Tor users.

Web Fingerprint

Iceweasel is configured to match the fingerprint of the Tor Browser Bundle and the known differences, if any, are listed in the known issues page.

However the fact that different extensions are installed in Tails and in the TBB surely allows more sophisticated attacks that usual fingerprint as returned by tools such as https://panopticlick.eff.org/ and http://ip-check.info/. For example, the fact that Adblock is removing ads could be analyzed.

Network Fingerprint

From the point of view of the local network administrator, Tails is almost exclusively generating Tor activity and that is probably quite different from other TBB users. We believe this would be hard to avoid.

If the censorship circumvention option (implemented as bridge mode) or possible future Tails detection protection option is enabled, we want the network fingerprint detection resistance, at least to the extend, that it beats DPI boxes at least as good as the censorship circumvention tool (implemented using pluggable transports) does.

And there https://tails.boum.org/contribute/design/Time_syncing /#index5h1 I’d remove:

"Tails developers still need to think thoroughly of these questions: are such fingerprinting possibilities a serious problem? What kind of efforts and compromise should be made to prevent these?"

Related issues

Original created by @tails on 5975 (Redmine)

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