Secure key agreement for group communications

-Many key establishment protocols have been proposed for secure group communications. However, these protocols share the limitations that group members are not mutually authenticated, dynamic group membership is not considered, and the cost of key establishment is substantial. A secure key agreement protocol for group communications is proposed in this paper, which ensures the authenticity of group members and the privacy of group messages, and provides the properties of forward and backward privacy. In a group session, the common key is collaboratively established by all participants, hence the overhead of key agreement is balanced among group members. The proposed protocol is an ID-based scheme, which has the advantages that the dedicated central server is not required, and group members need not exchange secret or public key information. To adapt it to a large multicast network, the scalability issue is also addressed. Keywords--secure group communications, key agreement, ID-based scheme, secure multicast