A Distributed Trust Mechanism for Mobile Ad Hoc Networks

In a multi-hop hop mobile ad hoc network (MANET), mobile nodes cooperate with each other without using any infrastructure such as access points or base stations. The nodes´ mobility and fundamentally limited capacity of the wireless medium, together with wireless transmission effects such as attenuation, multi-path propagation, and interference combine to pose significant challenges for security in MANETs. Traditionally, cryptographic mechanisms such as authentication and encryption are not capable of handling some kinds of attacks such as packet dropping by malicious nodes. In this paper, we propose a mechanism for detection of malicious packet dropping attack in MANET. The mechanism depends on a trust module based on the ´reputation´ of different nodes in the network. Every node computes the reputation of its neighbors by directly monitoring their behaviors. The reputation information is gathered, stored, and exchanged between the nodes and computed under different scenarios. We have validated the scheme with some simulation work, which shows the feasibility and efficiency of performance of the protocol.