[tbb-bugs] #7256 [Tor Browser]: Explore zoom-based alternatives to fixed window sizes

Tor Bug Tracker & Wiki blackhole at torproject.org
Thu Jul 31 16:13:50 UTC 2014

#7256: Explore zoom-based alternatives to fixed window sizes
     Reporter:           |      Owner:  tbb-team
  mikeperry              |     Status:  new
         Type:  project  |  Milestone:
     Priority:  normal   |    Version:
    Component:  Tor      |   Keywords:  tbb-fingerprinting, tbb-bounty,
  Browser                |  tbb-firefox-patch
   Resolution:           |  Parent ID:
Actual Points:           |
       Points:           |

Comment (by cypherpunks):

 Hello, another "cypherpunks" here.

 I'm not code-literate enough to know if this would actually work/be
 feasible, but

 I've been thinking for some time that maybe a better approach to the
 window size issue would be to increase the amount of "noise" in the user
 data, rather than trying to shoehorn all users' data into a "uniform"
 What I'm thinking of is '''varying the window size by a certain
 margin/formula on each startup / 'New Identity' (torbutton)'''. Now
 obviously the variation can't be too great or it will be an anti-feature,
 but i'd think something around the size/s of the various
 toolbars/scrollbars/etc. (ca. 25-50px?) wouldn't be too intrusive, and as
 a bonus would obfuscate what bars individual users have visible (and also
 i guess window decorations in case those matter?)

 Additionally, window size could perhaps be tied more ''flexibly'' to
 available full screen size, instead of the current slightly heavy-handed
 formula. What about something along these lines?
 actual screen area * 95% [optimal percent might be different?]
  +/- random vertical 'margin' [e.g. 25px*(random float between -3 and 3) ]
  +/- random horizontal 'margin' [as above]

 Tying the size roughly to full screen size should(?) give acceptable sizes
 for the majority who are accustomed to full-screen web browsing, while
 still providing some randomization/obfuscation. Thus it could be
 ''"advisable"'' for users to leave the window size to whatever the browser
 makes it, but it wouldn't be a huge deal if you toggle fullscreen on/off,
 fiddle with toolbar and similar settings, etc. - it would all be mostly
 within the 'noise' margin for that (hopefully fairly common) screen size,
 and thus not that identifying data.

 I guess there could also be an upper limit in the formula - owners of
 larger than average screens can spare the real estate (alternatively the
 formula could scale somehow, i guess), whereas users with smaller screens
 need to make use of the whole screen, or at least most of it. (BTW, with
 the current formula, i have to manually resize the window all the time
 because the default 'rounding' results in an absolutely stupid size on my
 smallish screen). Also, smaller, nonstandard screen sizes are increasingly
 common, so it makes sense to make more data noise/obfuscation at that end
 - and as a bonus, this probably would also benefit those who deliberately
 use partial-screen sizes for whatever reasons.

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/7256#comment:17>
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