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Re: [tor-bugs] #16267 [Tor Browser]: NoCaptcha Recaptcha is not working because of canvas fingerprint blocking
#16267: NoCaptcha Recaptcha is not working because of canvas fingerprint blocking
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Reporter: szgal | Owner: tbb-team
Type: defect | Status: new
Priority: normal | Milestone:
Component: Tor Browser | Version:
Resolution: | Keywords: tbb-usability-website
Actual Points: | Parent ID:
Points: |
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Comment (by mcs):
I do not know enough about NoScript to evaluate the proposed fix. Kathy
and I did examine this issue from a canvas fingerprinting perspective. It
turns out that Google's JS code does access canvas data; it draws images
to a canvas and then uses toDataUrl() to pull out the data.
Unfortunately, Tor Browser blocks access without showing a prompt on pages
such as the www.codediesel.com demo because of the third party
relationship. The following was logged to the Browser Console (very long
URL truncated for brevity):
On http://www.codediesel.com/demos/google-recaptcha/: blocked access to
canvas image data from document
https://www.google.com/recaptcha/api2/frame?c=03AHJ_VutAFy..., script from
https://www.gstatic.com/recaptcha/api2/r20150604090638/recaptcha__en.js:268
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16267#comment:3>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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