Re:Tor at the Heart: Firefox
by muizelaar on Tuesday January 03, 2017 @10:02AM
(#13309537)
I think this is an over-estimation of the amount of entropy. If canvas hardware acceleration is disabled, the only things that can really have an impact on the output of the panopticlick canvas fingerprint are OS version, user-agent and available cpu vectorization instructions.
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Interesting. I wonder to what extent one could trap vectorization instructions in e.g. KVM. Presumably they are unprivileged instructions on x86?
> Presumably they are unprivileged instructions on x86?
They're all unprivileged; having to go to the kernel would defeat the purpose most of the time.
Also, trapping them wouldn't make a difference. Fixing the CPUID fields on the other hand (so that these code paths are not taken in the first place)...