Assessing Security and Performance: Varying Ring Oscillator Counts in Configurable Inversion Unit-based PUF

The concept of Physical Unclonable Function (PUF) has recently garnered attention in both industrial and academic fields as a promising hardware primitive for enhancing the security of electronic systems and devices. PUFs leverage inherent manufacturing inconsistencies to generate a distinct key for every device. PUFs utilize the inherent manufacturing variations to generate a distinct key for each device despite using identical input values across all devices. A range of PUF types have been developed, such as optical, electronic, and magnetic variations. However, the Ring Oscillator (RO) PUF stands out particularly due to its simple implementation and impressive performance. Due to the limited combinations of the RO-PUF input-output bits, or as it is called in the field of PUFs, challenge-response pairs (CRPs), researchers have developed the configurable ring oscillator (CRO) PUF, which produces a larger set of CRPs by utilizing a configurable inversion unit (CIU) instead of the standard inverter in the traditional design. Most of the recent research primarily focuses on increasing the size of the CRPs and enhancing security features. Yet, there is a lack of emphasis on investigating how the count of ROs affects the performance of the CRO-PUF. This paper uses several performance metrics to investigate the impact of altering the ring oscillator count on the CRO-PUF.