US Patent 9218477 Electronic physical unclonable functions

An electronic asymmetric unclonable function applied to an electronic system being evaluated includes an electronic system and an AUF array electronically associated with the electronic system. The AUF array includes a plurality of non-identical cells. Each of the non-identical cells includes a test element representing a characteristic of the electronic system being evaluated and a measurement device evaluating the test element. A comparison unit processes an output of the measurement device to provide a multi-bit output value representing a magnitude of differences.