In Vehicular Ad Hoc Networks (VANETs), selfish nodes (vehicles) who do not contribute to the networks are considered as a threat, so vehicles are forced to participate into the network by sharing the information they collect on the road, whereas participation is optional for nodes in vehicular cloud and they are encouraged to participate with incentives as the network utilizes vehicles' underutilized resources to provide services. Hence, it is necessary to have an integrated incentive system for vehicular cloud, which combined VANET and cloud. The incentive system should be able to cover the entire vehicular cloud, including vehicles in the VANET and service providers in the cloud. In addition, the system must be robust against attacks. In this paper, we present an efficient scheme, Secure Token Reward System in Vehicular Clouds (STORS). It ensures the scalability of the incentive system and provides mechanism for securing incentive-related messages. Also, issued tokens can be used by vehicles to get services from the cloud.