The fundamental challenge in opportunistic networking, regardless of the application, is enabling node cooperation in order to forward a message. While node cooperation is considered as a fundamental property in such networks, ensuring such a property between two devices in mobile opportunistic networks remains largely unexplored. In this paper, we investigate the potential impact of the lack of trust on node cooperation. We adopt a real-trace driven approach to study and analyze the trade-off between trust and success delivery rates in opportunistic networks. We first explore leveraging social information to establish trustworthy communication for mobile opportunistic networks. We then propose six trust based filters that use three social-based estimators of trust including common interests, common friends, and the distance in the social graph, coupled with two major techniques of trust establishment including Relay-to-Relay, and Source-to-Relay. We finally show that our trust filters yield a fair trade-off between trust and success rate by achieving more than 35% success rate compared to an untrusted environment where 10% of the nodes refuse to cooperate in the absence of trust.
