Renewal of Pre-shared Key for Secure Communication of Multiple Mobile Terminals through Broadcast Data Distribution Systems

To perform the secure communication of multiple mobile terminals (i.e. secure unicast communi- cation or secure multicast communication), the encryp- tion key should be shared among the terminals that join the communication. In such a case, if the same encryp- tion key would be repeatedly used, the key disclosure from the stolen terminal might cause the wire tapping and decryption of the encrypted communication. To minimize the risk of the disclosure, the renewal of pre- shared key must be operated. In this paper, we propose the renewal method of pre-shared key for secure com- munication of multiple mobile terminals. In this method, each terminal will renew its pre-shared key by one-way function (e.g. hash function) according to the instruction from the management server. We also apply the pro- posed method to the secure communication systems between multiple mobile terminals where the key renew- al commands from the system management server to each mobile terminal is distributed through the broadcast data distribution systems.