USER AUTHENTICATION SYSTEM, USER AUTHENTICATION METHOD, AUTHENTICATION SERVER PROGRAM AND CLIENT PROGRAM

PROBLEM TO BE SOLVED: To provide a convenient user authentication system that makes it difficult to guess a password. SOLUTION: In the user authentication system 1 including a client terminal 4 and an authentication server 2, a registered password and an input password comprise a plurality of identification elements 133, and the client terminal 4 includes an authentication pattern display information setting means 46 for arranging identification elements 133 displayed on an authentication pattern display means 47 differently every time a user is requested to enter an input password. A password input part 50 is configured to acquire an input password by prompting a selective input of the identification elements 133 displayed on the authentication pattern display means 47, and a onetime password generation means 49 is configured to encrypt the input password with a onetime password. COPYRIGHT: (C)2011,JPO&INPIT