TPKEY: Using TPMS Signals for Secure and Usable Intra-Vehicle Device Authentication

Modern vehicles increasingly support wireless connectivity with various mobile devices, but existing authentication methods like Bluetooth pairing create unnecessary friction in shared mobility scenarios. This paper presents TPKEY, a novel zero-involvement authentication protocol that leverages tire pressure monitoring system’s (TPMS) radio transmissions to allow secure and autonomous device authentication within vehicles. The system extracts high-entropy keys from demodulated TPMS signal characteristics that are only accessible within the vehicle’s physical boundary. Our implementation addresses key technical challenges, including precise time synchronization between devices and efficient entropy extraction from raw signals. Extensive evaluation of TPKEY achieves $100 \%$ authentication success rate for legitimate devices, while maintaining $0 \%$ false acceptance rate for adversaries, with key generation time of $\mathbf{1. 3 ~ s}$. Furthermore, TPKEY maintains reliable performance across various driving conditions and device positions within the vehicle, offering a practical solution for seamless and secure device authentication in modern automotive environments.