Mitigating Relay Attacks in Vehicle Access Systems Using BLE and UWB

The technology for accessing vehicles has evolved significantly from traditional mechanical keys to advanced keyless systems, utilizing smartphones and smart wearables. The conventional LF-RF-based Passive Entry and Passive Start (PEPS) systems, struggle with inherent vulnerabilities. In particular, they suffer from relay attacks that exploit signal amplification to bypass proximity detection mechanisms. As vehicles become more connected through V2X and other shared mobility ecosystems, securing access systems is more critical than ever. To address these challenges, this research proposes a secured vehicle access framework that combines Bluetooth Low Energy (BLE), Ultra-Wideband (UWB), and Near Field Communication (NFC). Our system introduces multi-layered defense mechanisms, including asymmetric encryption-based digital key applets, dynamic Unique Rolling Session Keys (URSKs), and UWB-based secure ranging, using Time Difference of Arrival (TDOA) and trilateration techniques for precise user localization. BLE is used exclusively for authenticating the legitimate device. Passive unlocking is permitted only after proximity is verified by UWB, ensuring that the user’s device is truly near the vehicle. The development process utilized ANSYS HFSS 3D High Frequency Simulation for dual antenna design which enabled precise calibration. The implementation was achieved using a chipset with an ARM Cortex M33 core with hardware accelerators. Our experiments demonstrated that the system reliably triggers door unlock within only a 1.6 m radius, thus effectively mitigating relay attack risks. This framework offers a robust, future-ready, and user-centric solution for next-generation vehicle access control.