Authentication device, authentication system, and authentication method

An authentication system comprising:

• an authentication device configured to perform authentication of a user;
• and
• at least one use terminal connected to a network, the use terminal being used to provide the user with a service, wherein
• the authentication device includes:
• an acquisition unit configured to acquire biological information about the user;
• an authentication processing unit configured to perform an authentication process by comparing current biological information with standard biological information about the user, the current biological information being the acquired biological information;
• a storage unit configured to store the standard biological information and basic biological information about the user, the basic biological information being registered in advance;
• and
• a standard biological information updating unit configured to perform a process for updating the standard biological information based on the basic biological information,
• when a difference between the standard biological information and the current biological information is less than a predetermined first threshold, the authentication processing unit determines that authentication is established, and
• when a difference between the basic biological information and the current biological information is equal to or greater than a predetermined second threshold and a difference between the basic biological information and the standard biological information is less than the predetermined second threshold, the standard biological information updating unit updates the standard biological information according to the current biological information for which the authentication is established.

An authentication method comprising:

• acquiring biological information about a user;
• storing standard biological information used for an authentication process, and basic biological information about the user, the basic biological information being registered in advance;
• determining that authentication is established when a difference between the standard biological information and current biological information as the acquired biological information is smaller than a predetermined first threshold;
• and
• updating the standard biological information according to the current biological information for which the authentication is established, when a difference between the basic biological information and the current biological information is equal to or greater than a predetermined second threshold and a difference between the basic biological information and the standard biological information is less than the predetermined second threshold.