Fingerprinting 2.0: hardwareConcurrency

[cuba]

Description:

Based on the requirements here: brave/brave-browser#10808
Note: we are applying the basic farbling requirements.

Summary

Farble window.navigator.hardwareConcurrency to be a value between 2 and the true value.

Setup testing environment

1. Enable Web Inspector. This is done in the Settings app on the device under Safari -> Advanced
2. Enable debugging tools on safari (desktop).

Testing:

Farbling tests can be found here:
https://dev-pages.brave.software/fingerprinting/farbling.html

Additional tests

1. Connect phone to computer using a cable
2. Open up browser and navigate to any link (YouTube.come, Brave.com, whatever)
3. Open web inspector in safari -> Develop -> ->
4. Ensure Fingerprint protection is disabled
5. In the console write window.navigator.hardwareConcurrency You should have a true value (this will likely be 8)
6. Ensure Fingerprint protection is enabled
7. In the console write window.navigator.hardwareConcurrency You should have a fake value between 2 and the true value (note the true value may appear too)
8. Repeat this for other sites. Each page may give you a different random value (this is the point). But some sites may have the same random value (we don't have a huge list of random values to chose from)

[srirambv]

Verification passed on the following devices running 1.39 (22.5.24.16)

• Verified test plan from #5269 & on https://fingerprint-protection-test.herokuapp.com/
• Verified with FP enabled the value is lower than the true value
• Verified with FP disabled show the true value
• Verified on older devices, the test shows NaN when FP is enabled and undefined when FP is disabled

Device/OS	☑️ iPhone 7+ (iOS 14.8.1)	☑️ iPhone XR (iOS 15.3)	☑️ iPad Pro (iOS 15.5)
Fingerprint ON
Fingerprint OFF