The AMD Versal™ device contains a physically unclonable function (PUF). The PUF creates a signature (or fingerprint) of each device that is unique to that device. Its value is unknown to AMD and device user by design and can be used as a key encryption key (KEK). This KEK is 256 bits in length with 256 bits of entropy and is used to encrypt the users red key allowing its storage in black (encrypted) form. The black key can be stored in either eFUSEs, BBRAM, or external storage.
PUF outputs a user accessible unique ID that is cryptographically isolated from the PUF KEK itself despite using the same entropy source. While unique to each device, it is not considered a secret and does not have the same access protections as the KEK itself.