The key challenge of dynamic peer communication is how to realize secure and efficient group key management. A two rounds key agreement protocol for dynamic peer group (DPG) is proposed in this paper. The protocol, which was obtained by combining the ElGamal encryption scheme with the ElGamal signature scheme, is efficient and simple. The protocol is proven secure against passive attack by using indistinguishable method. Moreover, both perfect forward secrecy (PFS) and key independence (KI) were achieved. Because the protocol is based on the broadcast channel, it is also suitable for key agreement in wireless communications, especially in ad-hoc networks.
