Efficient Authenticated ID-Based Group Key Agreement Protocol

Abstract
Group key exchange protocols play main role in group applications such as computer networks, telecommunication and military systems. Given the wide range of usage of group applications, research and design of these protocols can play an important role in securing international exchanges, trade and military issues. Most existing group key exchange protocols establish multi-party or group key exchange protocols based on extending the two party well known Diffie-Hellman key exchanges. The security of these protocols is based on this assumption that difficulty of solving group Diffie-Hellman problem can be reduced to the difficulty of two party Diffie-Hellman problems. In spite of this assumption, Group key exchanges are not simply extension of two party protocols. In fact there are many differences and challenges that must be considered in design and implementation of these protocols. This difference is due to essential difference between peer to peer communication and group communication. In group communication in addition to considering the main goal e.g. obtaining group session key, consideration of group member changing is important too. In this paper, a Dynamic ID-based Group Key Agreement protocol based on Weil pairing is proposed. This complete ternary tree structure is used and dynamic changes in group are considered too. Finally we show that the proposed protocol is more efficient than other protocols with similar structure and also satisfies all known security requirements.