In the harsh environment where node density is sparse, the slow-moving nodes cannot effectively utilize the encountering opportunities to realize the self-organized identity authentications, and do not have the chance to join the network routing. However, considering most of the communications in opportunistic networks are caused by forwarding operations, there is no need to establish the complete mutual authentications for each conversation. Accordingly, a novel trust management scheme is presented based on the information of behavior feedback, in order to complement the insufficiency of identity authentications.

By utilizing the certificate chains based on social attributes, the mobile nodes build the local certificate graphs gradually to realize the web of ???Identity Trust??? relationship. Meanwhile, the successors generate Verified Feedback Packets for each positive behavior, and consequently the ???Behavior Trust??? relationship is formed for slow-moving nodes. Simulation result shows that, by implementing our trust scheme, the delivery probability and trust reconstruction ratio can be effectively improved when there are large numbers of compromised nodes, and it means that our trust management scheme can efficiently explore and filter the trust nodes for secure forwarding in opportunistic networks.