Massive amounts of data are sent and received in a vehicle traffic network, data involving countless vehicles, movements of people in the hundreds of millions, and their data, which get bundled with external environment data. The gathered data must at least be shared with legitimate users and depending on the situation data access privileges also need to be controlled. Because data between vehicles and the fog server may be subject to personal privacy infringement, a security technique must be introduced, such as encryption. To ensure secure sharing and use of data by users of a service, an encryption scheme is needed. Furthermore, delegation and revocation of decryption privileges are needed with this encryption scheme, concerning data encrypted based on user attributes. In this paper, we proposed a system that is safe from open recruitment attacks using an attribute-based authority delegation management method. The proposed system proved safe against publicly recruited attacks by malicious users using a semantic safety model. The proposed system can be applied to protect against smart car attacks. In the future, the encryption and calculation load will be reduced.