Note: As of version 67 Mozilla Firefox now has U2F enabled by default.
Initially when FIDO U2F support was introduced to Firefox, prior to version 67 it was turned off by default. In order to enable U2F support in the older builds, follow the steps below:
- Type "about:config" (without quotes) into the Firefox address bar and press Enter
- Search for “u2f”
- Double-click on security.webauth.u2f to set the value to enable. Once set to enable the U2F will be enabled on your browser. Alternatively you can right-click and select Toggle to change the value as well.
If this doesn't work, contact your IT department to determine if there are policies set which prevent users from changing security settings in Mozilla Firefox.
It is important to understand that every FIDO U2F implementation can vary from the official specifications. Some sites supporting FIDO U2F have made accommodations for the incompleteness of Firefox’s implementation, but some have not. In other situations, some services may not work with older versions of Firefox because of a service-specific implementation. Though now enabled by default it is still possible that a service may not work if the service is checking for user-agent ( e.g. Firefox ) instead of the availability of the U2F. Facebook is one such service that does not support U2F within Firefox. Google allows U2F login in Firefox, but requires Google Chrome be used to register the security key initially.