A novel low hardware configurable ring oscillator (CRO) PUF for lightweight security applications

Abstract

Physical unclonable function (PUF) is a promising hardware security primitive that can generate a unique secret key peculiar to each chip by extracting the differences of non-reproducible manufacturing variations for the same implementations. Although there are several types of PUF designs and structures, ring oscillator (RO) PUF is one of the most prominent PUFs due to its straightforward implementation and remarkable performance. However, the traditional RO-PUF does not support large sizes of input/output combinations or challenge-response pairs (CRPs), as it is called in the scope of PUFs. Consequently, RO-PUF is more vulnerable to adversary attacks which can reveal the PUFs’ CRPs using a machine learning approach. Increasing the size of RO-PUF's CRPs requires a high increase in the circuit size leading to unacceptable area overhead for lightweight applications. The primary technique used to increase RO-PUF CRPs’ size without increasing the size of the required hardware is to develop a configurable ring oscillator (CRO) PUF. In this paper, we propose a configurable logic unit (CLU) that can be utilized to build a low-hardware CRO-PUF. The proposed CLU consists of a 1-XOR gate and a 1-XNOR gate. Building a CRO-PUF using the proposed CLU dramatically increases the CRPs size while minimizing the required hardware. The proposed CRO-PUF achieves excellent evaluation results, with measured uniqueness of 50.1 %, uniformity of 49.45 %, and reliability of 98.33 %. These values are in close proximity to the ideal targets of 50 % for uniqueness and uniformity, and 100 % for reliability