| 摘要 |
PROBLEM TO BE SOLVED: To provide a user authentication system that can prevent unauthorized use. SOLUTION: When a mobile phone 20 receives provision of a service of a service provision unit 32, a telephone number and an IP address as an authentication key sent from the mobile phone 20 are transmitted to a user authentication unit 30 via the Internet 26 or a leased line 34. An IP address filtering unit 28 receiving the authentication key via the Internet 26 does not transmit the authentication key to the user authentication unit 30 if the authentication key includes an IP address given by a converter 24. The authentication key sent via the leased line 34, on the other hand, is transmitted to the user authentication unit 30, which authenticates the user. Even when an unauthorized user tries to unauthorizedly use the system in a way of a pretended mobile phone user by acquiring the authentication key transmitted through the Internet 26, the IP address filtering unit 28 does not transmit the authentication key to the user authentication unit 30. |
