Duty-Cycle-Based Controlled Physical Unclonable Function

Physical unclonable functions (PUFs) provide a unique signature based on the variations during the fabrication process of the integrated circuits. The additional features of controllability and reconfigurability to a PUF implementation enable the reuse of the existing hardware as a new modified PUF, enhancing the capabilities of a PUF for more versatile security applications. In this paper, a variable duty-cycle-based ring oscillator circuit is proposed as a controlled and reconfigurable PUF primitive. One of the distinguishing features of the proposed PUF is that duty cycle comparisons are used, instead of the conventional frequency comparisons to generate the output hit response. The advantages of the utilizing duty cycle over the conventional frequency-based comparisons are investigated. The feasibility of the proposed PUF is evaluated using existing figures of merit providing a uniqueness of 49.3%, temperature reliability greater than 92% between 0 and 100 degrees C, and supply voltage reliability greater than 96% between 0.9 and 1 V.