APAuth+: A Lightweight Mutual Authentication Scheme in Backscatter Communications

Backscatter Communication (BC) enables ultra-low-power wireless connections by employing simple Backscatter Devices (BDs) to reflect and modulate incident radio frequency (RF) signals for data transmission. Due to its inherently open nature, security in BC has becomes a main concern in practical applications. Mutual authentication between a BD and an RF source serves as a primary security mechanism to verify the legitimacy of devices, authenticating the origin of received signals. However, achieving mutual authentication in BC systems is challenging due to the severe computational and energy constraints of BDs. Previous work cannot solve this issue in an effective way. To address this issue, this paper presents APAuth+, a lightweight and efficient authentication protocol designed specifically for BC systems. APAuth+ exploits the inherent ability of BDs to harvest energy from incoming RF signals and integrat this capability into the authentication process, which consists of three phases: initialization, preparation, and authentication. Concretely, APAuth+ relies on secure power-harvesting measurements and secret-key verification to perform mutual authentication between the BD and the AP. Security analysis shows that APAuth+ is resilient against a wide range of attacks, including eavesdropping, replay, relay, brute-force, and jamming attacks. Both theoretical analysis and numerical simulations confirm the accuracy, robustness, and efficiency of APAuth+ under diverse operating conditions. Comparative results further demonstrate that APAuth+ outperforms existing authentication schemes in terms of authentication accuracy, efficiency, and attack resilience.