AUTHENTICATION METHOD, AUTHENTICATION SYSTEM, KEY GENERATOR, SERVER DEVICE, AND PROGRAM

PROBLEM TO BE SOLVED: To provide a two-elements authentication technology that has a low security risk. SOLUTION: In a system including a key generator for generating a master secret key and a public key of ID-based encryption, a first server device, a second server device, and a user device, two-elements authentication to the user device is performed by using first authentication information to the first server device and the second authentication information to the second server device. The second server device encrypts the second authentication information by using ID information of the first authentication information and a public key and obtains encrypted second authentication information. The encrypted second authentication information is sent to the key generator via the user device. The key generator authenticates the first server device by using the first authentication information, and decrypts the encrypted second authentication information by using the ID information of the first authentication information and the master secret key to obtain decryption information. The second server device determines whether the decryption information obtained via the user device coincides with the second authentication information. COPYRIGHT: (C)2011,JPO&INPIT