Patent ID: 7424605

Claim:
A communication system having a plurality of wireless access points for connecting a client terminal, and a server apparatus, said server apparatus comprising: authentication device for authenticating a client terminal which is connected to a first wireless access point; informing device for informing said first wireless access point, to which the client terminal is connected, of an encipher key that is used for wireless point-to-point communication between the client terminal and the first wireless access point in accordance with the result of the authentication by said authentication device; determination device for determining whether or not a client terminal has been authenticated on the basis of identification information of the client terminal informed from a second wireless access point; and control device for requesting said informing device to inform the second wireless access point of a same encipher key as an encipher key informed to the first wireless access point and instructing the first wireless access point to delete the encipher key, in accordance with the determination result by said determination device, said first wireless access point comprising a first transmission device which enciphers a broadcast key for a wireless point-to-multipoint encipher communication between said first wireless access point and the client terminals with the encipher key informed by said informing device, and transmits the enciphered broadcast key to the client terminal, and said second wireless access point comprising a second transmission device which enciphers a broadcast key for a wireless point-to-multipoint encipher communication between said second wireless access point and the client terminals with the encipher key informed by said informing device, and transmits the enciphered broadcast key to the client terminal.