Reliable low-overhead arbiter-based physical unclonable functions for resource-constrained IoT devices

Physical unclonable functions (PUFs) are promising hardware security primitives suitable for resource-constrained devices requiring lightweight cryptographic methods. However, PUF responses frequently suffer from instability due to varying environmental conditions such as voltage and temperature. In this paper, we introduce circuit-level techniques to enhance the reliability of delay-based PUFs against temperature variation. We propose a voltage controlled current starved (VCCS) delay element that can effectively reduce temperature sensitivity and thus improve the reliability of PUF responses. Built on the VCCS delay element, two test-case arbiter-based PUF architectures are implemented in a standard 65nm CMOS technology and validated through post-layout Monte-Carlo simulation. Evaluation results show that two proposed PUF designs satisfy requirements on randomness, uniqueness, and reliability over a wide temperature range. Moreover, the proposed approach imposes only a marginal overhead leading to one of the most energy-efficient PUFs in the state-of-the-art.