الفهرس 
Chapter 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
group key management is one of the basic building blocks in collaborative and group-oriented applications in Mobile Ad hoc Networks (MANETs). group key establishment involves creating and distributing a common key for all group members. Exchanging cryptographic keys and key management for a group of nodes has been a problem with respect to security. Several researchers used Diffie-Hellman key exchange algorithm to overcome this problem. Since then, the concept of key exchange over an unsecured network has completely been revolutionized. One of the limitations of the Diffie-Hellman algorithm is that it is computationally intensive thereby increasing the time complexity when generating public keys. The other issue is the Modification of membership requires the group key to be refreshed to ensure backward and forward secrecy. The applied algorithm “General Multiplicative Diffie-Hellman (GMDH)” has similar grounds with the Diffie-Hellman algorithm. GMDH algorithm uses simple arithmetic equations to generate and exchange keys over an insecure network. It overcomes the time complexity limitation of the Diffie-Hellman algorithm. We also present an enhanced technique called a Transition Key Management Scheme (TKMS), that is based on GMDH. TKMS expects to minimize the key management overhead in the network because of highly dynamic sessions of membership comparing with the other techniques. The results showed that the applied algorithms GMDH and TKMS reduced the computation overhead of group key generation. In the initialization the GMDH has computation over head lower than SEGK by 27%. Also, for the TKMS has lower computation overhead than the GMDH by 18% in the leave phase. The algorithms enhanced the network performance through prolong the network lifetime and increase the through put. The GMDH prolong the network lifetime by 29% more than the SEGK, The TKMS has network lifetime more than the GMDH by 8%.