Physically Unclonable Function Using Schnitt Triggers

Abstract

Physically unclonable functions or PUFs are innovative physical security primitives which produce unclonable and inherent instance-specific measurements of physical objects; PUFs are in many ways the inanimate equivalent of biometrics for human beings. Since they can securely generate and store secrets, PUFs allow to bootstrap the physical implementation of an information security system. Physically Unclonable Functions (PUF) are security primitives to combat Integrated Circuit (IC) cloning and counterfeiting. The response of the PUF is expected to be stable under environmental fluctuations (e.g., temperature and voltage fluctuation). Our analysis indicates that conventional arbiter PUF experiences significant variations due to environmental fluctuation degrading quality. In this paper we propose a novel Schmitt-Trigger (ST) based PUF that exploits the susceptibility of ST to process variations to realize high-quality robust arbiter type PUF. We have used 5 different types of ST level by level to change overall delay of the circuit. We have used an Inverter-based conventional arbiter PUF structure. The response is determined based on relative delay between paths. The path selection is done by challenges. The overall circuit is 3-bit circuit which includes multiplexers and flip flops as well. To show encryption i.e., to generate a set of keys we have used a 3-bit circuit having eight outputs.