Patent ID: 7975293

Claim:
An authentication method for authenticating a third node which applies to participate in a workgroup comprised of a first node and a second node which are in a network system, the authentication method comprising the steps of: transmitting a temporary authentication ticket including a digital signature of the third node from the third node to the first node; authenticating the third node by the first node based on the digital signature of the temporary authentication ticket received from the third node; transmitting a password for participating in the workgroup from the third node to the first node; verifying by the first node the password received from the third node; generating a regular authentication ticket by the first node by adding a digital signature of the first node to the temporary authentication ticket to transmit the regular authentication ticket to the third node in a case where the third node has been successfully authenticated based on the digital signature, and the password is correct; transmitting from the third node to the second node the regular authentication ticket received from the first node; authenticating the first node and the third node by the second node based on the digital signatures of the regular authentication ticket received from the third node; and causing the second node to permit the third node to access, as a node of the workgroup, the second node in a case where the first node and the third node have been successfully authenticated.