Overview#U2F device is a FIDO Authenticator that supports the Universal Second Factor FIDO protocol
U2F device interface types#At the moment (2017-04-02) three interface types are specified in FIDO U2F.
- Universal Serial Bus (USB)
- Near Field Communication (NFC)
- Bluetooth (Classic and Smart aka Low Energy (BLE)).
The user can use the same FIDO U2F device on all online services that support the U2F device protocol.
Existing FIDO U2F Security Keys are largely compatible with the W3C WebAuthn standard, though W3C WebAuthn added the ability to reference a unique per-account "user handle" identifier, which older hardware tokens are unable to store.