Towards Secure IoT: A Lightweight PUF-Based Proximity-Aware Authentication Protocol for Resource-Constrained IoT Devices
Internet of Things (IoT) devices face significant security challenges due to their limited computational and memory resources, making conventional cryptographic mechanisms unsuitable for many deployments. This paper presents a lightweight PUF-based proximity-aware authentication protocol designed for resource-constrained IoT devices. The proposed approach integrates a hardware-efficient configurable XOR Ring Oscillator (RO) PUF with a lightweight authentication framework supporting proximity verification and environmental awareness. The PUF architecture achieves 49.2% inter-chip uniqueness and $\mathbf{1. 6 8 \%}$ average intra-chip variation across temperature ranges from $0-60^{\circ} \mathrm{C}$ while reducing area overhead by approximately 40% compared to conventional designs. A novel multifunction circuit based on Quad Field operations enables efficient authentication token generation with a 60% reduction in powerdelay product while incorporating architectural countermeasures against modeling, side-channel, and relay attacks. The protocol also incorporates a lightweight distance-bounding mechanism that verifies physical proximity within 3 meters using only 128 FPGA clock cycles. The PUF core requires only 66 LUTs and 4.36 mW, and the complete authentication protocol executes in 3.72 ms at 22.73 mW total power on a Xilinx Nexys-A7 100T FPGA. These results demonstrate that the proposed architecture provides an efficient and practical security solution for resourceconstrained IoT environments.