| 摘要 |
[Problem] To selectively provide, in accordance with a user terminal a CAPTCHA that can be easily executed by an operator of the user terminal. [Solution] A web server (11) determines the type of web browser running in a user terminal (13). An authentication server (12) decides a CAPTCHA execution program on the basis of the type of web browser that has been determined. The authentication server (12) executes the decided CAPTCHA execution program to generate problem data and correct answer data. The web server (11) provides the CAPTCHA to the user terminal (13) on the basis of the problem data. The authentication server (12) compares the correct answer data and answer data generated by the user terminal (13), and determines whether authentication has succeeded or failed. |
