In group-oriented applications like conferencing, chat groups and interactive gaming myriad messages are sent from one or more sources to multiple users. Multicasting is the optimum technique for such group oriented applications with effective network resource utilization. But maintaining security is a critical issue in group oriented protocols with frequent membership changes. Confidentiality can be achieved through changing the key material, known as rekeying every time a new member joins the group or existing member leaves from the group. Many techniques have been proposed earlier for this purpose. In centralized approach, a single key server is responsible to generate and distribute keys. In decentralized approach, a hierarchy of key managers distributes the keys. In distributed key-agreement protocol, the group members collectively generate and distribute a group key. This paper uses combination of both de-centralized and key agreement approaches to prevent a single point of failures and to improve the reliability as well as the performance of the system. This paper proposes new a technique(SGKP-1), using hybrid key trees, has certain advantages like secure channel establishment for the distribution of the key material, reducing the storage requirements and burden at each member, minimization of time requirement to become a new member of a group. The computational complexity further reduced using both the combination of public and private key crypto systems.
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