Now that all UK passport holders have NFC passports, they should just say 'touch your passport to the back of your phone to log in'.
The passports support challenge-response auth, allowing gov.uk to securely identify the passport in a way a device cannot spoof, and the Web NFC API is implemented quite widely now.
The passports support challenge-response auth, allowing gov.uk to securely identify the passport in a way a device cannot spoof, and the Web NFC API is implemented quite widely now.