How can I lower Screen Size & Color Depth bits of identifying information

[Ewald Böhm]

How can I lower Screen Size & Color Depth bits of identifying information?

These are my results when I visit panopticlick.eff.org:
1. Firefox: Screen Size and Color Depth 15.19 37,501.06 2400x1350x24
2. TBB: Screen Size and Color Depth 9.4 676.6 1000x700x24

Where the "bits of identifying information" is 15.19 & 9.4 respectively,
resulting in 1 in every 37,501.06 Firefox browsers having a "screen size
and color depth" of 2400x1350x24, while one in 676.6 browsers have a
screen size and color depth value of 1000x700x24.

Architecdture = amd64, Desktop = KDE
Distro = Ubuntu trusty
Version = jessie/sid
Nonfree kernel modules = nvidia
Uname = Linux 3.13.0-48-generic x86_64
KDE Development Platform: 4.13.3, Qt: 4.8.6

Given that my goal would be to blend in better with the crowd while using
Firefox, what specifically can we do to get Firefox to report better
numbers?

[Ewald Böhm]

On Sat, 05 Sep 2015 22:10:28 -0500, Ewald Böhm wrote:

> These are my results when I visit panopticlick.eff.org:
> 1. Firefox: Screen Size and Color Depth 15.19 37,501.06 2400x1350x24
> 2. TBB: Screen Size and Color Depth 9.4 676.6 1000x700x24

I don't understand why Firefox gives away the most privacy of the three
browsers I tested.

Can anyone EXPLAIN why Firefox is the worst on giving away screen privacy?

Screen Size and Color Depth

Chrome = 1920x1080x24
Tor TBB = 1000x700x24
Firefox = 2400x1350x24

bits of identifying information
Chrome = 3.59
Tor TBB = 9.4
Firefox = 15.19

one in x browsers have this value
Chrome = 12
Tor TBB = 15.19
Firefox = 37,501.06

More importantly, how do I FIX firefox to NOT give away the farm?

[Chris Isle]

Ewald Böhm brought next idea :

Look at this add-on.

https://addons.mozilla.org/en-us/firefox/addon/random-agent-spoofer/

I would download the version from Github to realize the maximum
benefit.

[EE]

Look at the column heading that says "one in x browsers have this value"
and see which items underneath have the largest numbers. That is what
contributes the most to making you unique. For me, it is the browser
plugin details, followed by the user-agent, not the screen size or the
fonts.

[Ewald Böhm]

How does the Tor Browser Bundle get Firefox to report the BROWSER size
while Chrome reports the SCREEN size, and while Firefox reports some
strange unknown size?

http://www.whatismyscreenresolution.com/
Firefox: You are using 2400 X 1350
Chrome: You are using 1920 X 1080
Tor Browser Bundle: You are using 1000 X 700

If, in Firefox or Chrome, you change the window size, you still get the
same numbers. But in Tor Browser Bundle, if you change the browser size,
you get different numbers.

Given that anyone can easily reproduce my results above, does *anyone*
actually know what is going on with why the three browsers report three
different numbers?

Clearly the way the Tor Browser Bundle does it is best, but, does anyone
have any idea whatsoever as to HOW Tor Browser Bundle accomplishes this?

[Ewald Böhm]

On Sun, 06 Sep 2015 07:40:53 -0700, Chris Isle wrote:

> Look at this add-on.
>
> https://addons.mozilla.org/en-us/firefox/addon/random-agent-spoofer/
>
> I would download the version from Github to realize the maximum
> benefit.

The problem has nothing to do with any addon.

The question is simply *how* does firefox work?

Here are my results, pointing all three browsers, at the same time, to:

http://www.whatismyscreenresolution.com/

Firefox: You are using 2400 X 1350
Chrome: You are using 1920 X 1080
Tor Browser Bundle: You are using 1000 X 700

Only 1 out of 3 browsers gets it right, which is Chrome.

$ xrandr
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 8192 x 8192

Why does *only* Chrome get the screen size and resolution correct?
More importantly, since I hate Chrome and love Firefox, how do I get

[Ron K.]

Firefox is gathering the screen size data from the OS. It is hard coded
that way. TBB must be designed and coded to use it's window size. Chrome
is a puzzle and I can't guess what it is doing.

--
Ron K.
Who is General Failure, and why is he searching my HDD?
Kernel Restore reported Major Error used BSOD to msg the enemy!

[Ewald Böhm]

On Mon, 07 Sep 2015 22:10:39 -0500, Ron K. wrote:

> Firefox is gathering the screen size data from the OS. It is hard coded
> that way. TBB must be designed and coded to use it's window size.
> Chrome is a puzzle and I can't guess what it is doing.

But, Firefox is the only one that is wrong.

I know what the correct screen size and resolution is.

So, I suspect there is a setting, in about:config perhaps, that tells
Firefox how to do its math.

But what setting is Firefox using to report the (wrong) screen size and
resolution?

The correct resolution is only reported by the Tor Browser Bundle (which
reports the window size) and by Chrome (which correctly reports the
screen size).

Only Firefox is wrong.
But, how does Firefox arrive at this wrong information?

$ xdpyinfo | grep 'dimensions:'
dimensions: 1920x1080 pixels (341x191 millimeters)

[Ewald Böhm]

On Mon, 07 Sep 2015 22:10:02 -0500, Ewald Böhm wrote:

> Why does *only* Chrome get the screen size and resolution correct? More
> importantly, since I hate Chrome and love Firefox, how do I get Firefox
> to report better numbers?

I just figured something very useful out if you want to change what
Firefox reports to www.whatismyscreenresolution.com/ as the screen size!

about:config layout.css.devPixelsPerPx = -1 (You are using 960 X 540)
about:config layout.css.devPixelsPerPx = 1 (You are using 1920 X 1080)
about:config layout.css.devPixelsPerPx = 2 (You are using 960 X 540)
about:config layout.css.devPixelsPerPx = .5 (You are using 3840 X 2160)
about:config layout.css.devPixelsPerPx = .8 (You are using 2400 X 1350)

So, if you want Firefox to appear to be any desired screen size, you can
change the layout.css.devPixelsPerPx value.

What is a good *common* screen size to have Firefox report?

[Caver1]

Just out of curiosity I tried the above settings and got resolutions at
panopticlick that did not
match what you have above, with any of them.

--
Caver1

[Mark Lloyd]

On 09/07/2015 10:10 PM, Ewald Böhm wrote:

[snip]

> Why does *only* Chrome get the screen size and resolution correct?
> More importantly, since I hate Chrome and love Firefox, how do I get
> Firefox to report better numbers?
>

I checked the following with the link you gave:

Linux: Firefox, Chrome, Opera
Linux (another PC): Firefox, Chrome, Opera
Windows 7: Firefox, IE
Windows XP: Firefox, IE8, IE5
Mac: Firefox, Safari

All were current versions except the older IE on XP. All showed the
correct screen size.

--
108 days until the winter celebration (Friday December 25, 2015 12:00:00
AM for 1 day).

Mark Lloyd
http://notstupid.us/

"Why is it when we talk to God we're said to be praying, but when God
talks to us we're schizophrenic?" -- Lily Tomlin

[EE]

What about Secret Agent? Does that fake screen size as well as user-agent?

[Caver1]

No but if you have Secret Agent change the user agent on every http
request,over ride the accept header, send spoofed etags, and spoofed
headers, it doesn't really matter what your reported screen size is,
your fingerprint constantly changes.

--
Caver1

[Ewald Böhm]

On Mon, 07 Sep 2015 22:10:39 -0500, Ron K. wrote:

> Firefox is gathering the screen size data from the OS. It is hard coded
> that way. TBB must be designed and coded to use it's window size. Chrome
> is a puzzle and I can't guess what it is doing.

Actually it's not.
But, I solved the problem.

[WaltS48]

Would you like to share the solution?

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