A group key agreement protocol from pairings

We propose an n-round key agreement protocol for any N-participants, where 3n−1 < N ⩽ 3n, using the tripartite Joux key agreement protocol from pairings in combination with a divide-and-conquer strategy. The security of this protocol is based on the hardness of the bilinear Diffie-Hellman problem and the computational Diffie-Hellman problem.