RC PUF: A Low-Cost and an Easy-to-Design PUF for Resource-Constrained IoT Devices

A physically unclonable function (PUF) is a security primitive that can generate device-specific cryptographic information by extracting the features of hardware uncertainty. Despite the advantages of PUFs introduced over the past decade, the majority of them have to be implemented on a separate chip or embedded as a part of a chip, making it difficult to use them in low-cost IoT devices. To increase the usability of PUFs in IoT devices, we propose a novel resistor-capacitor (RC) PUF that can be configured at low cost. The main feature of this RC-based PUF is that it extracts the small difference caused by charging and discharging of RC circuits and uses it as a response. Experimental results show that the proposed RC PUF has more than 49% uniqueness while maintaining over 98% reliability. It also reveals less than 1% stability at 10% voltage changes from 3.3 V to 3.0 V, representing very robust characteristics against voltage variations. For temperature changes from −30 °C to 70°, the stability is maintained below 4%.