A method, of an aspect, includes challenging a set of Physically Unclonable Function (PUF) cells, of an integrated circuit device, and receiving a set of PUF bits from the PUF cells in response. A PUF key is generated based on the set of PUF bits. An encryption of the PUF key with an embedded key is output from the integrated circuit device. The integrated circuit device receives an encryption of a fuse key with the PUF key. Fuses of the integrated circuit device are programmed with at least one of the fuse key and the received encryption of the fuse key with the PUF key. Other methods, apparatus, and systems are also disclosed.