Abstract
This research presents an improved hierarchical key management scheme (IHKMS) with three phase technique for secure group communications in Mobile Ad-hoc Networks (MANETs). It extends two previously proposed models named enhanced hierarchical key agreement scheme (EHKMS) and EHKMS with three phase technique which suffer from two main problems. The first one which exists in both models is that, the main subgroup controller (L1-head) is heavily loaded and has a lot of responsibilities which may lead to its failure. The second problem that exists only in EHKMS is intrusion attacks which may appear in two aspects; frank intrusion and selfish attack. This problem is a fatal one which threatens the security of the system. The proposed IHKMS with three phase technique solves the above mentioned problems. First, it decreases the memory load on the main subgroup header to save its memory resources by distributing a major part of subgroup keys storage into the second level of subgroups headers. Second, it immunizes the IHKMS against intrusions by employing the three phase technique. Applying the three phase technique integrates a certification authentication system in addition to the hierarchal key system used in the IHKMS. The proposed IHKMS with three phase technique enhances EHKMS and EHKMS with three phase technique. It improves the system’s reliability in EHKMS, and EHKMS with three phase technique by minimizing the subgroup header’s load. Also, it overcomes the intrusion problem that exists only in EHKMS. On the other hand, the complexity of the proposed IHKMS with three phase technique is higher than that of EHKMS. This is anticipated result as the proposed model integrates the three phase technique with the IHKMS.