Methods for Fast Cryptographic Key Generation from Memristor-Based Physically Unclonable Computed Functions

Description

When operating at very low power, arrays of memristors are unclonable and can be used to design cryptographic key generators and exploit the dependencies of their resistance values with the injected current. Additionally, at low power the memristors are not retaining information or acting as non-volatile memory. The difficulties of such designs include the inherent limitations behind legacy physical unclonable functions (PUFs) and the slowness to accurately measure high ephemeral resistance values in the 10 M? range. This protocol replaces the initial responses of the PUF with responses computed from analytical parameters. These parameters, which are stored in a look-up table of the server, are generated upfront during enrollment cycles from the physical parameters of memristor arrays. The protocol replaces the PUF challenges with a set of instructions also computed from the analytical parameters at the server level. They are transmitted to the client device containing the memristor array through unsecured networks. Rather than generating the PUF responses from the memristor array by rereading the ephemeral resistance values of the cells, the responses are generated by injecting small currents, typically 100 nA, and comparing the voltage across the memristor cells with the voltage across certain reference cells available in the array.

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