How to enable FIDO U2F in Firefox?

The latest version of Firefox supports FIDO2 and U2F keys :

FIDO2 has been supported since version 66.0.32.

U2F has been supported since version 57, but only enabled by default from version 68 onwards.

If you need to enable U2F support on an early version (57 and later) of Firefox, please follow the steps below:

  1. Within the address bar at the top of the browser, type in “about:config” and press enter
  2. If you see a warning page, click the “I accept this risk!” button to continue
  3. Type “u2f” into the search box at the top of the page, above the list of preferences, which will filter the list
  4. You should then see a setting/option “security.webauth.u2f” with its value set to “false
  5. Right-click on this line and then click “Toggle” in order to enable it
  6. Check that the “value” for this option is now shown as “true”

You can now close this page and try using your Key-ID U2F token with your favourite online services, with Firefox!