Patent ID: 8005460

Claim:
A group authentication method adaptable to a communication system, wherein the communication system comprises a first group, a serving network, and a home network, the first group comprises at least one mobile station, the serving network has a first database for recording a plurality of group lists and group authentication data received from the home network, the home network pre-distributes a group authentication key and a mobile station authentication key to the mobile station and itself, the home network has a second database for recording the group lists generated by the home network, and the group authentication method comprises: identifying action to the mobile station through the serving network; and determining whether the communication system performs a full authentication action or a local authentication action through the serving network according to the result of the identification action, and a mobile station authentication and key distribution step; wherein the full authentication action comprises: the execution of the home network authentication, the mobile station authentication, and key distribution; wherein the local authentication action comprises: a transient authentication key obtaining step, wherein the transient authentication key obtaining step comprises: retrieving the group authentication data from the first database through the serving network, wherein the group authentication data contains which contains a group transient key (GTK) generated at the home network according to the group authentication key; wherein the group list comprises a group number, the group authentication key, a mobile station ID, an initial value, and a group related message, and the mobile station has the group number, the mobile station ID, and the initial value; wherein the identification action comprises: requesting an identification data from the mobile station through the serving network; generating a first random number through the mobile station, and then generating the identification data according to the mobile station authentication key and the first random number through the mobile station; and transmitting the identification data to the serving network from the mobile station; wherein the mobile station has a mobile station authentication message generation function, and the method for generating the identification data comprises: inputting the first random number and the mobile station authentication key into the mobile station authentication message generation function stored in the mobile station to calculate a first message authentication code (MAC); and combining the group number, the mobile station ID, the first random number, and the first MAC through the mobile station to generate the identification data.