[tor-bugs] #30541 [Applications/Tor Browser]: webgl readPixels FP entropy

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#30541: webgl readPixels FP entropy
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 Reporter:  Thorin                               |          Owner:  tbb-
                                                 |  team
     Type:  defect                               |         Status:
                                                 |  needs_review
 Priority:  Very High                            |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-fingerprinting,                  |  Actual Points:
  TorBrowserTeam201905R, GeorgKoppen201905       |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by gk):

 Replying to [comment:7 Thorin]:
 > Replying to [comment:6 cypherpunks]:
 > > Also your test shows...webgl2: supported.. But `webgl2` shouldn't be
 allowed.
 >
 > Thanks. If the browser reports that webgl2 is supported, that's one bit
 of entropy. I'll double check with some tests and kkapsner (it's his
 code), opened an issue [1]. This is a browser level API check
 >
 > What the browser does in a test after that can provide more entropy: e.g
 error entropy (e.g blocked at a different step of the process: e.g slider
 settings, click to play, extension interference, etc), or provide a hash
 >
 > Not sure if meant the API check is flawed, or if TB blocks `WebGL2`.

 We explicitly set `webgl.enable-webgl2` to `false` to make sure no WebGL2
 APIs are accessible.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/30541#comment:8>
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