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Preventing Canvas Fingerprinting in Slimjet

Canvas fingerprinting is a kind of tracking technology used by website operators to uniquely identify a visistor against other visitors. It does so without relying on cookies or IP address or user agents sent by the browser. Instead, this technlogy uses Javascript to draw some image onto a HTML5 canvas element. Depending on the graphics card and video driver used in the user's system, the pixels on the canvas will be different from those drawn on another computer. Another Javascript method can be used to export the pixels on the canvas, which then can be used to generate a hash and sent back to the server.

Slimjet includes an option "Disable reading from HTML5 canvas" in the security section of the settings page. If you turn on this option, javascript wouldn't be able to export any pixels from the canvas and the server wouldn't be able to get any unique fingerprint information.

For more information about canvas fingerprinting, please visit this blog post.