[tor-bugs] #4810 [Firefox Patch Issues]: Weird screen sizes reported by Panopticlick

[Tor Bug Tracker & Wiki]

#4810: Weird screen sizes reported by Panopticlick
-------------------------------------+-------------------------------------
     Reporter:  erikd                |      Owner:  mikeperry
         Type:  enhancement          |     Status:  needs_revision
     Priority:  major                |  Milestone:  TorBrowserBundle
    Component:  Firefox Patch        |  2.3.x-stable
  Issues                             |    Version:
   Resolution:                       |   Keywords:
Actual Points:                       |  Parent ID:
       Points:                       |
-------------------------------------+-------------------------------------

Comment (by ben):

 I filed the same bug as #10833. I've proposed exactly the same fix there:
 * Hardcode a set of a common screen resolutions. Then, pick the smallest
 that can fit the current window size.

 Concretely:
 {{{
 actual screen size | window size | screen size cur | screen size proposed
    1920x1200       |  1057x909   |   1057x909      |   1920x1080
    1920x1200       |  1057x1100  |   1057x1100     |   2880x1800
    1280x720        |  1270x685   |   1270x685      |   1920x1080
    1280x720        |  1000x600   |   1000x600      |   1920x1080
    1280x720        |   800x400   |    800x400      |   1920x1080
 }}}

 1. There will only be 2 resolutions within TBB: 1920x1080 and a very high
 one. This reduces entropy to exactly 1 bit (2 values) within TBB.
 2. The screen size can change for an individual user, which is strange,
 but it's currently the case with the current fix as well.

 This would be strictly better (some cases better, no case worse) than the
 current solution.

 -----

 We can't allow window resizes //requested by the website// and window size
 queries anyway, because they allow tagging/matching sessions within the
 same window.

 Unusual window sizes are still a problem, but that's for another ticket to
 solve. Unusual screen sizes stand out a lot more, though - //even for
 websites that do not specifically target Tor users//.

 -----

 Reproduction:
 1. Start browser
 2. Resize window manually to a size that pleases me
 3. Go to <​​http://browserspy.dk/screen.php> and
 <​​http://browserspy.dk/window.php>

 Actual result standard Firefox:
 window size: 1057x909
 screen size: 1920x1200

 Actual result Tor browser:
 window size: 1057x909
 screen size: 1057x909 (that's the "bug")

 Expected result Tor browser:
 window size: 1057x909
 screen size: 1920x1080 (that's the fix)

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4810#comment:8>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online