Canvasblocker: Panoptclick tests show my canvas fingerprint hash is staying the same

[DRigby26]

Description

When I use the fake readout API and test it with Panoptclick, it shows that the hash of my canvas fingerprint is the same every time.

Expected Behavior

As I understand it the fake readout API is supposed to produce a different readout every time the API is called.

Current Behavior

The fake readout API is the same every time.

Possible Solution

Steps to Reproduce (for bugs)

1. Go to the Panopticlick website.
2. Test your browser several times and look at the results of the Hash of canvas fingerprint
   3.
   4.

Context

Your Environment

• CanvasBlocker Version used: Canvas 0.4.5 C
• Firefox version incl. 32- or 64-bit: Firefox 60.0.2 64 bit
• Operating System and version (desktop or mobile): Mac OSX 10.13.5
• Installed addons:

Your Settings

My Block mode is set to fake readout API

[kkapsner]

I'm not able to reproduce your problem - I get a different hash every time.
Can you please provide your full settings (enable expert mode and then export the settings) - you may want to remove the "persistentRndStorage". Especially your "rng" can cause the issue.

[DRigby26]

{
"logLevel": 1,
"urlSettings": [],
"whiteList": "",
"blackList": "",
"blockMode": "fakeReadout",
"minFakeSize": 1,
"maxFakeSize": 0,
"rng": "nonPersistent",
"apiWhiteList": {},
"useCanvasCache": true,
"ignoreFrequentColors": 0,
"minColors": 0,
"fakeAlphaChannel": false,
"persistentRndStorage": "",
"storePersistentRnd": false,
"persistentRndClearIntervalValue": 0,
"persistentRndClearIntervalUnit": "days",
"lastPersistentRndClearing": 1528922554800,
"askOnlyOnce": "individual",
"askDenyMode": "block",
"showCanvasWhileAsking": true,
"showNotifications": true,
"storeImageForInspection": false,
"notificationDisplayTime": 30,
"ignoreList": "",
"showCallingFile": false,
"showCompleteCallingStack": false,
"enableStackList": false,
"stackList": "",
"displayAdvancedSettings": true,
"displayDescriptions": true,
"isStillDefault": false,
"storageVersion": 0.3
}

[DRigby26]

Okay, I did a fresh install of Firefox without any extensions or anything and it now is working the way it is supposed to work so the problem was on my end. Thank you for this extension!

[DRigby26]

I narrowed down the problem to being when you have the resistFingerprinting config enabled for Firefox, it will stop this extension from working.

[kkapsner]

Thank you for digging deeper. The behaviour with resistFingerprinting is known and I thinks it's good the way it is (I could not even change it).
If you check my test page (http://kkapsner.github.io/CanvasBlocker/test/test.html) you will see that the resistFingerprinting generates a white image. But you are not always prompted for the permissions when the canvas is not visible...

You can find further information on this topic in https://github.com/ghacksuserjs/ghacks-user.js/issues/350 and https://github.com/ghacksuserjs/ghacks-user.js/issues/429