[tor-talk] TorBrowser spoofed screen size?

Joe Btfsplk joebtfsplk at gmx.com
Thu Mar 6 05:05:18 UTC 2014

On 3/5/2014 7:52 PM, Soul Plane wrote:
> I tried TBB 3.5.2 in Windows XP at 120 dpi and browserspy says I'm at 96.
Yes, that's screen "resolution," or just resolution.  It's of some 
significance, but it's not the same as "screen (or monitor) size."
Screen size is what I meant (like 1280 x 720, etc.).  That's the value 
I'm asking what TBB is now supposed to spoof (what IS that value).

Note:  it may? be working correctly for me (dunno)... except, since 
neither I nor millions, keep their system DPI set at default (in 
Windows, often 96), then the TBB spoofed screen size, modified by the 
DPI adjustment, gives a VERY weird number (sort of like:  1657 x 841, 
1920 x 892 etc.).  So weird, it's probably FAR more noticeable / unique, 
than just showing my real screen size, or somehow? spoofing my own 
(believable) value.

But, EVEN WHEN  I reset my system to 96 DPI, reboot - TBB still shows a 
weird value - like 1920 x *933* (just an example).
NO one has a screen size w/ those odd numbers.  That's the issue.

Try checking your screen size at these sites (they do thorough jobs, in 
varying degrees).
They're quite well known.   At BrowserSpy.dk, must click each test 
separately.  There, the test is "screen."
You may have to enable javascript (if turned off) in NoScript, for some 
sites to detect certain browser or system values (a lesson unto itself 
about JS giving up info).

But, at least *parts* of many sites won't work w/o java script - a 
double edged sword.

Browser check sites:
 From JonDoFox group: IP check <http://ip-check.info/?lang=en>
Panopticlick-EFF.org_Browser.Uniqueness <https://panopticlick.eff.org/>
BrowserSpy.dk_Browser Privacy Tests <http://browserspy.dk/resolution.php>
> I've never checked the resolution before so I don't know how it compares to earlier versions.
I can't remember what TBB was reporting, the last time I checked on one 
of those sites.
For those using system default DPI values, TBB may be correctly spoofing 
a fairly common is size (or not).

If others would, please check to see if it's spoofing a "common" screen 
size, or a weird one.
If you report a "sort of" size back here, please state if you use 
default OS DPI value, or higher / lower.

I read a bunch on Trac, but *never found* the final draft for what 
size(s) they'd show.  I'm pretty sure none of the choices were 1920 x 869.

More information about the tor-talk mailing list