Security is an essential service for wired and wireless network communications. The success of mobile networks strongly depends on people's confidence in its security. However, the characteristics of MNET pose both challenges and opportunities in achieving security goals, such as confidentiality, authentication, integrity, availability, access control, and non-repudiation. The wireless nature and inherent features of mobile networks make them exposed to a wide variety of attacks. In an internal attack, the attacker gains the normal access to the network and takes part in the network activities, either by some malicious imitation to get the access to the network as a new node, or by directly compromising a current node and using it as a basis to conduct its malicious behaviors. In this paper, we develop a cluster based validation methods to lessen internal attacks. The entire network is divided into hierarchical group of clusters, each cluster having a fully trusted cluster head. Each node holds a certificate issued by an offline certificate authority (CA). The Trust Count (TC) for each of the nodes can be estimated periodically for every trust evaluation interval (TEI), based on their access policy (AP). The certificate of a node is renewed or rejected by the cluster head, based on its trust counter value. By simulation results, we show that our proposed technique provides better packet delivery ratio and resilience against node capture.

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Node Capture Attacks Clustering Trust Count Access Policy