The ubiquity of communication networks is facilitating the development of wireless and Internet applications aimed at allowing users to communicate and collaborate amongst themselves. In the future, group-oriented services will be one of the dominant services that facilitate real-time information exchange among a large number of diverse users. However, before these group-oriented services can be successful deployed, technologies must be developed to guarantee the security of the information and data exchanged in group communications.

Among all security requirements of group communication, access control is paramount as it is the first line of defense that prevents unauthorized access to the group communication and protects the value of application data. Access control is usually achieved by encrypting the data using a key that is shared among all legitimated group members. The problem of access control becomes more difficult when the content is distributed to a dynamic group with user joining and leaving the service for a variety of reasons. Thus, Group Key Management is required to achieve key update with dynamic group membership.

Existing group key management schemes seek to minimize either the amount of rounds needed in establishing the group key, or the size of the key updating messages. They do not, however, considering the varying requirements of the users, the underlying networks or the applications. Those generic solutions of access control often yield large consumption of communication, computation and storage resources. In addition, the design of existing key management schemes focus on protecting the application data, but introduces vulnerabilities in protecting the statistics of group membership information. This poses severe security concern in various group applications.

The focus of this dissertation is to design network-specific and application specific group key management and solve the security vulnerability of key management that reveals dynamic group membership information. This dissertation will present scalable group key management in heterogeneous wireless network, the hierarchical access control for multimedia applications, and a framework of securing dynamic group membership information over multicast. The main contribution of this dissertation is to advance the group key management research to achieve higher level of scalability and security.