Bugzilla

Chrome's "UA reduction" effort [1] froze Chrome Android's `navigator.platform` as `Linux armv81`, regardless of the Android device's actual CPU architecture. Firefox Android RFP currently spoofs `navigator.platform` as `Linux aarch64`, but we should return the same value as Chrome to reduce browser differences.

This change is only active when the `privacy.resistFingerprinting` pref is enabled, such as in the Tor Browser.

[1] https://www.chromium.org/updates/ua-reduction/#reduced-navigatorplatform-values-for-all-versions

Chrome's "UA reduction" effort [1] froze Chrome's `navigator.platform` as `Linux armv81` on Android and `x86_64` on Linux desktop, regardless of the device's actual CPU architecture.

[1] https://www.chromium.org/updates/ua-reduction/#reduced-navigatorplatform-values-for-all-versions

Freeze the CPU architecture reported in Firefox's `User-Agent` HTTP header and `navigator.userAgent` and `navigator.platform` Web APIs as `Linux armv81` on Android and `Linux x86_64` on Linux and other Unix-like platforms. Temporarily guard this change behind a pref so it can be disabled quickly, if needed.

Goals:

1. Reduce fingerprintable entropy exposed to web content.
2. Reduce risk of webcompat problems.

Chrome's "UA reduction" effort made the same change in Chrome 107 (2022-10-25): https://www.chromium.org/updates/ua-reduction/#sample-ua-strings-phase-5

Firefox Android's RFP mode currently spoofs `navigator.platform` as `Linux aarch64`, but let's return the same value as Chrome, `Linux armv81` to reduce browser differences that might cause webcompat problems.

Freeze the CPU architecture reported in Firefox's `User-Agent` HTTP header and `navigator.userAgent` and `navigator.platform` Web APIs as `Linux armv81` on Android and `Linux x86_64` on Linux and other Unix-like platforms. Temporarily guard this change behind a pref so it can be disabled quickly, if needed.

Goals:

1. Reduce fingerprintable entropy exposed to web content.
2. Reduce risk of webcompat problems from unexpected CPU architectures.

Chrome's "UA reduction" effort made the same change in Chrome 107 (2022-10-25): https://www.chromium.org/updates/ua-reduction/#sample-ua-strings-phase-5

Firefox Android's RFP mode currently spoofs `navigator.platform` as `Linux aarch64`, but let's return the same value as Chrome, `Linux armv81` to reduce browser differences that might cause webcompat problems.