Efficient group key agreement for wireless mobile networks

Group key agreement protocols are crucial for achieving secure group communications. They are designed to provide a lot of users with a shared secret for cryptographic purpose. In wireless mobile networks, low-power group members may join and leave the group frequently. Dynamic key agreement protocol is in need. It is desirable to minimize the number of rounds and the amount of computation of each member. In this paper, a dynamic authenticated group key agreement protocol for mobile networks is presented. It needs at most two rounds to establish or refresh a session key. When membership changes, the session key is refreshed efficiently and securely. By using members´ previous values, computation and communication costs are reduced in Join and Leave algorithms. Furthermore, there is no message exchange in Leave algorithm. Its security is proved under Decisional Bilinear Diffie-Hellman (DBDH) assumption in standard model and thus provides better security guarantees than previous results in random oracle model.