BRO PUF: A Bi-directional Ring Oscillator-Based PUF for IoT Security

Abstract

Protecting and securing a system for Internet of Things (loT) applications involve hardware-based security primitives. For the purpose of cryptographic key generation and authentication, Physically Unclonable Functions (PUFs) have emerged as the most widely used low-cost security primitives. This paper introduces the Bi-directional ring oscillator (BRO), featuring a configurable structure based on gated logic. Simulation results of the proposed BRO PUF, when compared to prior PUF designs, shows better uniqueness. Notably, the proposed PUF design generates twice as many CRP in comparison with the conventional ring oscillator (RO) PUF. The proposed BRO PUF design is implemented on 40-nm CMOS technology at a 1.1-V supply. To validate the functionality, the proposed design is implemented on a Basys-3 FPGA board for calculating various PUF parameters. The simulation result highlights that it possesses a uniqueness value of 0.498 and 0.492. We conducted a comparative study at different stages of BRO, focusing on delay and power. The number of stages in the proposed BRO PUF can be selected on the target application, enabling design flexibility while maintaining uniqueness and reliability. This work reports uniqueness 49.8% which is 1.01X, 1.004X, 1.02X compared to conventional RO and SRAM, RRAM, Static monostable-based PUF and bit alising 1.01X and recent state-o-art RO PUF designs, highlighting its enhanced performance. © 2025 Elsevier B.V., All rights reserved.