[tor-bugs] #13025 [Tor Browser]: Lie about the screen orientation

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#13025: Lie about the screen orientation
-------------------------+-------------------------------------------------
     Reporter:           |      Owner:  gk
  mikeperry              |     Status:  needs_review
         Type:  defect   |  Milestone:
     Priority:  major    |    Version:
    Component:  Tor      |   Keywords:  ff31-esr, tbb-easy, tbb-
  Browser                |  fingerprinting, TorBrowserTeam201410Easy, tbb-
   Resolution:           |  testcase, MikePerry201410R
Actual Points:           |  Parent ID:
       Points:           |
-------------------------+-------------------------------------------------

Comment (by gacar):

 I think the number of users with the vertical monitor setting may not be
 big enough to create a meaningful anonymity set.

 My primitive calculations with the Panopticlick data showed that enforcing
 a cutoff for the screen height (as TBB currently does for the width >
 1000px) reduces the overall entropy of TBB-resized screens from 2.63 to
 1.28 bits, and # of buckets from 43 to 13.

 https://github.com/gunesacar/tbb-fp

 Per pde's suggestion, I'll rerun these simulations after removing the
 possible TBB users from the raw data (to prevent double-resizing). Also, I
 plan to add some % of users with maximized screen size to the
 distribution. A related idea came up during the meeting with Mike was to
 resize the TBB window in a way to cover the users with maximized TBB
 windows.

 Here's the list of 10 most common screen dimensions after being resized by
 the current algorithm.
 Basically this the result of the following: take the screen dimension
 distribution from Panopticlick database, resize them as TBB would do,
 measure the entropy, number of buckets etc.

 WxHxColor_depth, Frequency  (Top ten)
 ==============
 ('1000x600x24', 426073),
 ('1000x900x24', 293909),
 ('1000x800x24', 233138),
 ('1000x700x24', 198246),
 ('1000x1000x24', 142745),
 ('1000x400x24', 33037),
 ('1000x500x24', 16585),
 ('800x400x24', 7835),
 ('1000x1400x24', 7350), V
 ('1000x1300x24', 6246), V

 WxHxColor_depth, Frequency  (Verticals, i.e. Height > Width)
 ==============
 ('1000x1400x24', 7350), V
 ('1000x1300x24', 6246), V
 ('1000x1100x24', 2216), V
 ('1000x1700x24', 1126), V
 ('1000x1500x24', 874), V
 ('1000x1200x24', 171), V
 ('1000x1900x24', 60), V
 ('1000x1600x24', 48), V
 ('600x1100x24', 22), V
 ('1000x1800x24', 21), V
 ('1000x2400x24', 15), V
 ('1000x2200x24', 14), V
 ('1000x2100x24', 6), V
 ('1000x5100x24', 4), V
 ('1000x9800x24', 3), V
 ('1000x3200x24', 3)] V

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13025#comment:17>
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