Patent ID: 7392385

Claim:
A client server system, comprising: a server device; a client device connected to the server device; and an authentication device connected to the server device; wherein an encryption key for encryption of data and a decryption key for decryption of the encrypted data are set to the server device; authentication information is set to the client device or a user thereof, the authentication information to be used for authentication of access authority to the server device when jobs are demanded of the server device; the client device uses the encryption key to encrypt authentication information for the server device and uses the encrypted authentication information to demand a predetermined job of the server device; the server device receives a demand for the predetermined job from the client device, the demand including the encrypted authentication information; the server device forwards the encrypted authentication information to the authentication device to demand authentication for the client device or the user, of the authentication device; the authentication device receives demand of authentication from the server device along with the encrypted authentication information, decrypts the encrypted authentication information by using the decryption key, authenticates the client device or the user on the basis of the decrypted authentication information, and returns a result of authentication for the client device or the user to the server device; and the server device executes the predetermined job which is demanded from the client device or the user when access authority has been authenticated by the authentication device.