Authentication device, authentication system, authentication method, program and recording medium

8) An authentication device for authenticating an inputter based on an input password accepted from the inputter, the authentication device comprising:

• a first input part for allowing the first part of the input password to be inputted in a predetermined input field;
• a confirmation information output part for outputting confirmation information known to the valid inputter in advance when the first part is valid, the confirmation information indicating to the user that the authentication device is valid;
• a second input part for allowing the second part of the input password to be inputted in the input field subsequently after the first part;
• and
• a determination part for determining that the inputter is valid when the first part and the second part are valid.

9) An authentication system comprising an input terminal for accepting an input password from an inputter and an authentication server for allowing the input terminal to authenticate the inputter,

• the input terminal comprising:
• a confirmation information obtaining part for obtaining from the authentication server, confirmation information known to the valid inputter in advance by the authentication server and indicating to the valid inputter that the input terminal is valid;
• a first input part for allowing the first part of the input password to be inputted;
• a confirmation information output part for outputting the confirmation information when the first part is valid;
• a second input part for allowing the second part of the input password to be inputted;
• and
• a determination part for determining that the inputter is valid when the first part and the second part are valid;
• and
• the authentication system comprising:
• a confirmation information transmission part for transmitting the confirmation information associated with the valid inputter in response to a direction by the input terminal.

10) An authentication method for authenticating an inputter based on an input password accepted from the inputter, the authentication method comprising the steps of:

• allowing the first part of the input password to be inputted;
• outputting confirmation information known to the valid inputter in advance when the first part is valid, the confirmation information indicating to the user that an authenticator is valid;
• allowing the second part of the input password to be inputted;
• and
• determining that the inputter is valid when the first part and the second part are valid.

11) An authentication method for authenticating an inputter based on an input password accepted from the inputter, the authentication method comprising:

• allowing the first part of the input password to be inputted in a predetermined input field;
• outputting confirmation information known to the valid inputter in advance when the first part is valid, the confirmation information indicating to the user that an authenticator is valid;
• allowing the second part of the input password to be inputted in the input field subsequently after the first part;
• and
• determining that the inputter is valid when the first part and the second part are valid.

12) A mutual authentication service provider providing a mutual authentication service for authenticating an inputter based on an input password accepted from the inputter via a computer as well as allowing the inputter to authenticate validity of a service site providing a predetermined service;

• the mutual authentication service comprising:
• an input password obtaining step for obtaining a valid input password set by the valid inputter in advance;
• a confirmation information obtaining step for obtaining confirmation information known to the valid inputter in advance and indicating to the valid inputter that the service site is valid;
• a first input step for allowing the first part of the input password to be inputted;
• a confirmation information outputting step for outputting the confirmation information when the first part is valid in comparison with the valid input password;
• second input step for allowing the second part of the input password to be inputted;
• and
• a notification step for notifying the service site that the inputter is valid when the first part and the second part are valid.

13) A program for causing a computer as an authentication device for authenticating an inputter based on an input password accepted from the inputter;

• the program causing the computer to function as:
• a first input part for allowing the first part of the input password to be inputted;
• a confirmation information output part for outputting confirmation information known to the valid inputter in advance when the first part is valid, the confirmation information indicating to the user that the authentication device is valid;
• a second input part for allowing the second part of the input password to be inputted;
• and
• a determination part for determining that the inputter is valid when the first part and the second part are valid.

14) A program for causing a computer as an authentication device for authenticating an inputter based on an input password accepted from the inputter;

• the program causing the computer to function as:
• a first input part for allowing the first part of the input password to be inputted in a predetermined input field;
• a confirmation information output part for outputting confirmation information known to the valid inputter in advance when the first part is valid, the confirmation information indicating to the user that the authentication device is valid;
• a second input part for allowing the second part of the input password to be inputted in the input field subsequently after the first part;
• and
• a determination part for determining that the inputter is valid when the first part and the second part are valid.

15) A program for causing a computer to function as a mutual authentication service provider providing a mutual authentication service for authenticating an inputter based on an input password accepted from the inputter as well as allowing the inputter to authenticate validity of a service site providing a predetermined service;

• the program causing the computer to function as:
• an input password obtaining part for obtaining a valid input password set by the valid inputter in advance;
• a confirmation information obtaining part for obtaining confirmation information known to the valid inputter in advance and indicating to the valid inputter that the service site is valid;
• a first input part for allowing the first part of the input password to be inputted;
• a confirmation information outputting part for outputting the confirmation information when the first part is valid in comparison with the valid input password;
• a second input part for allowing the second part of the input password to be inputted;
• and
• a notification part for notifying the service site that the inputter is valid when the first part and the second part are valid.