Hello. The problem in the images that I download or try to upload somewhere. Instead of the image itself, i get some multi-colored stripes are displayed on the jpeg/png or webp no matter.
In version 12.5.6 (32bit) this was not, but after a large update it appeared. On the old version everything still works good, but on all new ones this problem.
I tried to download clear Tor or changed bridges, nothing helped.
How fix it ? thank you.
Sorry for the bad English, I used the translator.
I believe this is happening because of Tor Browser’s defenses against HTML5 Canvas Image Extraction which is a browser fingerprinting vector.
HTML5 Canvas Image Extraction
After plugins and plugin-provided information, we believe that the HTML5 Canvas is the single largest fingerprinting threat browsers face today. Studies show that the Canvas can provide an easy-access fingerprinting target: The adversary simply renders WebGL, font, and named color data to a Canvas element, extracts the image buffer, and computes a hash of that image data. Subtle differences in the video card, font packs, and even font and graphics library versions allow the adversary to produce a stable, simple, high-entropy fingerprint of a computer. In fact, the hash of the rendered image can be used almost identically to a tracking cookie by the web server.
In some sense, the canvas can be seen as the union of many other fingerprinting vectors. If WebGL is normalized through software rendering, system colors were standardized, and the browser shipped a fixed collection of fonts (see later points in this list), it might not be necessary to create a canvas permission. However, until then, to reduce the threat from this vector, we have patched Firefox to prompt before returning valid image data to the Canvas APIs, and for access to isPointInPath and related functions. Moreover, we put media streams on a canvas behind the site permission in that patch as well. If the user hasn’t previously allowed the site in the URL bar to access Canvas image data, pure white image data is returned to the JavaScript APIs. Extracting canvas image data by third parties is not allowed, though.
Sources:
Okay, can you tell me how to fix it ?
My English is very bad, so please use the words easier.
I do not recommend doing this as blocking of canvas fingerprinting is a feature in Tor Browser, but on these particular websites where you face this issue you should be able to see a ‘canvas’ icon on the top-left of the URL bar. Click on the icon and click ‘Allow’.
It worked. Thank you so much.
Allowing a canvas exception for a website in Tor Browser is session only (i.e it only lasts until you close Tor Browser), and whilst it is a high entropy target (because it can include protected colors, glean GPU/graphics entropy, extra font entropy, etc), it is only exposed on those site(s) you allow it. So in a nutshell, it will likely expose you (fingerprint wise) somewhat on repeat visits (i.e to the first party) if you keep adding a session exception.
So use judiciously 
I saw such problem on website with reverse image search function.
It did not matter for me if they fingerprint me or not, I just needed search results.
At the time, I thought it’s a bug.
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