With the U2F authentication technique, in addition to the general access authorization with a password or biometric identification, another security feature such as a U2F security token is required to perform the complete authentication. U2F uses an encryption method based on the challenge- response method. The encryption is highly secure and protects the user from phishing, hijacking, man-in-the-middle attacks and malware. It is easy to use and can be deployed with various browsers.
Privacy is protected because the U2F process is secured so that personal data stored with the service provider cannot be used with other U2F devices, even if data is stolen. A U2F USB security token can be used as a second security factor; authentication can likewise be performed via NFC tags or using Bluetooth and a smartphone.
Universal Second Factor (U2F) is being further developed and promoted by the FIDO Association.