Bleichenbacher's Ghost

Hey man, computer security is hard.

Canvas Poison Pill: A Gif

Posted on — Sep 3, 2020;   Reading Time — 1 minutes
The figure illustrates the idea in https://bugzilla.mozilla.org/show_bug.cgi?id=1621433#c0
The intuition behind the canvas poison pill in 2 frames.

This idea is due Tom Ritter,1 who was inspired by a defense implemented in the Brave Browser.2 This defense is live in Tor Browser 10.0a6.

The source for this image is available.

Enabling This in Firefox

You can enable this by turning on the Resist Fingerprinting mode, which you can do by going to about:config and toggling the option privacy.resistFingerprinting to true.

Resist Fingerprinting mode is very strict and might break some websites, please report breakages to BugZilla.

Enabling This in the Tor Browser

This feature is currently active in 10.0a6 (Tor Browser Alpha) and should be available in Tor Browser Stable versions >10.

Further Reading


  1. Description of Bug 1621433 ↩︎

  2. Brave Issue 9186 ↩︎