A Dynamic ID based Authenticated Group Key Agreement Protocol
Through the group key agreement, all group members could negotiate a common session key which is used in later secure communication. While simple GKA cannot provide enough security to resist the adversary's attack, and the malicious damage during the agreement makes the authenticated key agreement particularly important. In identity based authentication, user's unique identity information is used as the public key, which makes it exempt from a series of management of the certification in public key infrastructure. Thereby, the identity based key agreement can simplify the key management procedures and reduce the risk of failure at the certification authority. Recently, several identity based group key agreement protocols have been proposed, however most of them are either vulnerable to impersonation and replay attack or inefficient and unscalable. This paper proposes a novel authenticated group key agreement protocol which is based on bilinear pairings. It needs two rounds to negotiate the session key, and the low computational complexity makes the protocol efficient and scalable. Meanwhile, our protocol also ensures the forward and backward secrecy and the key independence. Under the Decisional Diffie Hellman assumption, our protocol is proved to be secure against the adversary.