Enriching the electromagnetic fingerprint of RFID antennas by non-linear interrogation for Physical Unclonable Functions

This paper investigates the information content of fingerprints of passive RFID devices by applying Shannon Information Theory to backscattered signals. The study demonstrates that interrogations with multiple input powers and frequencies can exploit the non-linear behavior of the integrated circuit (IC), so that its impedance modulation will change in a non predictable way. Accordingly, the device will expose more information, resulting in a higher entropy value, and a richer fingerprint. This technique can be useful for the realization of Physical Unclonable Functions (PUFs) in anti counterfeiting applications.