Detection and Mitigation of Greyhole Attack in Wireless Sensors Network Using Trust Mechanism

Wireless sensors networks are generally deployed in mission critical environment. The nodes in the network are generally unattended and hostile environment in which they are deployed make the network vulnerable to many attack. One such attack is greyhole attack where the attacker selectively drops the packets in its path to sink or base station. Greyhole attack may reduce the network throughput or even lead to failure in the mission for which the network is deployed. So it becomes necessary to detect such attacks and mitigate it. Detection of greyhole attack is difficult as compare to other form of attack because the node implementing such attacks is the legitimate node having all the necessary cryptographic information. In this paper we have proposed the mechanism to detect and mitigate greyhole attack. We have used trust mechanism to detect the attack. Trust mechanism will calculate the trust value of the node in network which is similar to the concept of trust in human society and then this trust value is use to detect the malicious activity in our case packet dropping. We have used task completion and energy consumption as the parameters for calculating the trust value. There can be a situation where attacker can manipulated its attacking strategies to avoid itself from being detected. Our detection mechanism has also taken care of such situation.