The User Credential Protocol provides a method to identify the user of a platform. If a device provides a method to identify the user of a platform such as entering a password, reading a fingerprint, or reading a smart token, then a UEFI Driver that produces the User Credential Protocol should be implemented.
The EDK II provides the following two implementations of the User Credential Protocol in the
SecurityPkg. The fist one interacts with the user to retrieve a password entered through a keyboard. The second one uses a content stored on a USB Flash drive as a token.