A device which can be implemented on a single packaged integrated circuit or a multichip module comprises a plurality of non-volatile memory cells, and logic to use a physical unclonable function to produce a key and to store the key in a set of non-volatile memory cells in the plurality of non-volatile memory cells. The physical unclonable function can use entropy derived from non-volatile memory cells in the plurality of non-volatile memory cells to produce a key. Logic is described to disable changes to data in the set of non-volatile memory cells, and thereby freeze the key after it is stored in the set.