This extension is an authentication service for TYPO3 which extends the frontend and backend login process by strong two-factor authentication.
The two-factor authentication is provided by a TYPO3 users username and password combined with a OTP (one time password) which is generated by a YubiKey (a physical USB-key)
A YubiKey enabled user has to enter his username, password and a OTP to login to TYPO3s backend and/or frontend.
More information about the YubiKey, Yubico and the YubiCloud OTP validation service can be found at http://www.yubico.com
You can find a detailed documentation in the Documentation folder of the TYPO3 extension.
The extension is hosted on GitHub. Please report feedback, bugs and changerequest directly at https://github.com/derhansen/sf_yubikey