Communication system, server device, client device and method for controlling the same

A server device comprising:

• creation means for creating an encipher key used for communication between a client terminal and a first access point when the client terminal is permitted to be connected to a network through the first access point;
• and
• informing means for informing the first access point of the encipher key created by the creation means,
• wherein the informing means informs a second access point of the same encipher key as that informed to the first access point when the client terminal is connected to the network through the second access point.

A server device comprising:

• authentication means for authenticating connection of a client device to a network through an access point;
• informing means for informing an access point, to which the client device is connected, of an encipher key in accordance with a result of the authentication by the authentication means;
• and
• determination means for determining whether the client device which requests the authentication means to execute authentication is a client device or not, for which authentication has been finished,
• wherein the informing means informs the access point, to which the client device is connected, of a new encipher key in accordance with the determination of the determination means.

A client terminal connected to a network through an access point, comprising:

• creation means for creating an encipher key used for communication with a first access point;
• and
• communication means for executing encipher communication with the first access point by using the encipher key created by the creation means,
• wherein the communication means uses the encipher key used for the encipher communication with the first access point even when an access point connected for connection to the network is changed from the first access point to a second access point.

A control method for a communication system, comprising the steps of:

• creating an encipher key used for communication between a client terminal and a first access point when the client terminal is permitted to be connected to a network through the first access point;
• and
• informing the first access point of the encipher key created by the creation means,
• wherein in the informing step, a second access point is informed of the same encipher key as that informed to the first access point when the client terminal is connected to the network through the second access point.

A control method for a server device, comprising the steps of:

• creating an encipher key used for communication between a client terminal and a first access point when the client terminal is permitted to be connected to a network through the first access point;
• and
• informing the first access point of the encipher key created by the creation means,
• wherein in the informing step, a second access point is informed of the same encipher key as that informed to the first access point when the client terminal is connected to the network through the second access point.

A control method for a server device, comprising the steps of:

• authenticating connection of a client device to a network through an access point;
• informing an access point, to which the client device is connected, of an encipher key in accordance with a result of the authentication in the authentication step;
• and
• determining whether the client device which requests authentication in the authentication step is a client device or not, for which authentication has been finished,
• wherein in the informing step, the access point, to which the client device is connected, is informed of a new encipher key in accordance with the determination in the determination step.

A control method for a client terminal connected to a network through an access point, comprising the steps of:

• creating an encipher key used for communication with a first access point;
• and
• executing encipher communication with the first access point by using the encipher key created in the creation step,
• wherein in the communication step, the encipher key used for the encipher communication with the first access point is used even when an access point connected for connection to the network is changed from the first access point to a second access point.