Flamer: Flexible-Authorized Message Classification Against Message Recovery Attacks in Social IoV

The social Internet of Vehicles (SIoV) is promoting the deep integration of social networks into IoV systems, emphasizing the social communications and structures of cloud-assisted vehicle-to-vehicle socialization. Towards secure SIoV message classification, the methodology of certificateless public key encryption with equality test (CL-PKEET) is adopted. Nonetheless, existing solutions typically address threats only from either the vehicle side or the social cloud server side. Specifically, a vehicle may obtain private information via performing unauthorized public equality retrieval; and the cloud may launch message recovery attacks via exhaustively testing potential guessing messages. To simultaneously address threats from both sides, we present Flamer, a secure SIoV message classification system with Flexible-authorization that resists message recovery attacks. Technically, we revisit the dual-server architecture and roughly combine the flexible authorization mechanism into CL-PKEET. Beside presenting formal construction and security analysis, we implement state-of-the-art solutions and Flamer in real cloud environment. Extensive experiments under public dataset, along with network and traffic simulations, are conducted to confirm the practical performance of Flamer. It outperforms state-ofthe-art solutions by running 1.2× ∼ 1.58× faster for message classification, across the corresponding four authorization types with time efficiency improvements ranging from 1.84× to 5.5×.