| 摘要 |
PROBLEM TO BE SOLVED: To safely and efficiently update an authentication system to be used and a key to be used. SOLUTION: The authentication system comprises a step that a client device 20 transmits a random number r1, a step that a server device 10 enciphers data including the first random number, a random number r2 generated by the server device 10 itself, an authentication system A' to be updated, and a key K' to be updated by using a present key K, and transmits the enciphered data, a step that the client device deciphers the enciphered data by using the present key K, and verifies the deciphered data by using the random umber r1, a step that the client device enciphers and transmits the random number r2 in the deciphered data by using the key K' and the new authentication system A' in the deciphered data when the verified result is correct, a step that the server device deciphers the enciphered data by using the key K', and verifies the deciphered data by using its own random number r2, and transmits the verified result, and a step that the client device updates the new authentication system A' and the key K' based on the verified result. |
