TIS: A threshold incentive scheme for secure and reliable data forwarding in vehicular Delay Tolerant Networks

Delay Tolerant Networks (DTNs) have been utilized in wide-raging applications where a continuous end-to-end connection is unavailable and the message transmission is fulfilled by the cooperation among DTN nodes and follows a store-carry-and-forward manner such as vehicular networks. A series of incentive schemes were proposed to stimulate the selfish nodes to take on the energy-consuming job of forwarding bundles. However, the Onboard Units (OBU) equipped on vehicles are vulnerable to node compromise attack and the existing incentive mechanisms cannot well resist such sophisticated attacks sponsored by colluding vehicles and model the continuous collaboration among vehicles. In this paper, a novel threshold credit-based incentive mechanism is proposed based on the modified model of population dynamics to efficiently prevent the node compromise attacks, stimulate the cooperation among intermediate nodes, maximize vehicular nodes' interests and realize the fairness of possessing the same opportunity to forward packets for credits. Then, based on it, a secure and reliable packet forwarding protocol TIS is proposed. By devising a time order-preserving aggregated signature scheme, it also effectively solves the open problem of resisting the layer-adding attack launched by the collusion of intermediate vehicles. Finally, the security analysis and the extensive simulations show the effectiveness of our proposed TIS in resisting the sophisticated attacks mentioned above and the efficiency in terms of high reliability, high delivery ratio and low average delay in vehicular DTNs.