A security framework for content retrieval in DTNs

In this paper, we address several security issues in our previously proposed content retrieval scheme for Disruption Tolerant Networks (DTNs). The content retrieval is built upon the social-tie relationships among DTN nodes for routing and content lookup service placement. Malicious nodes can launch attacks by advertising falsified social-tie information to attract and drop packets intended for other nodes, or simply disrupt and destroy the query and delivery paths. Furthermore, selfish nodes, while not seeking to attack, are unwilling to forward packets of others. Both malicious and selfish behaviors contribute to the deterioration of the content retrieval performance. To address the problem, we propose to secure both social-tie records and content delivery records during a contact between two nodes. The unforgeable social-tie records prevent malicious nodes from falsifying the social-tie information. The delivery records from which the packet forwarding ratio of a node is computed, help detect selfish behavior. Lastly, we propose a blacklist distribution method that allows nodes to filter out misbehaving nodes from their social contact graph, effectively preventing network traffic from flowing to misbehaving nodes. Extensive real-trace-driven simulation results show that our scheme can detect misbehaving nodes and mitigate their effects efficiently, thus improving the content retrieval performance.