SCMP-V: A secure multiple relays cooperative downloading scheme with privacy preservation in VANETs

In vehicular ad hoc networks (VANETs), vehicle-to-vehicle cooperative downloading schemes have been provided to solve the problem of data download in the communication blind zone. However, how to realize the secure and reliable download of data by vehicles in the blind zone while preserving user privacy is still a problem to be solved in cooperative downloading. In this paper, we propose a secure multiple relays cooperative downloading scheme with privacy preservation in VANETs (SCMP-V), which mainly composes a secure relay selection algorithm, an adaptive data allocation mechanism, and an encrypted cooperative downloading method with privacy-preserving. Specially, we propose a secure relay selection method, which allows roadside units to select multiple relay vehicles while considering the most relevant criteria. Also, we propose an adaptive data allocation mechanism that can dynamically allocate the different sizes of data to the multiple relays by estimating the dynamic communication environment. Finally, we propose an encrypted cooperative downloading method based on key-policy attribute-based encryption, which can ensure target vehicles downloading the data with privacy-preserving. Simulation results show that SCMP-V can maintain a high transmission success rate and low packet loss rate for downloading data in different environments Compared with existing schemes, SCMP-V can improve the overall efficiency of relays selection and cooperative downloading by 13% and 27%, respectively while ensuring the privacy of vehicles.