A service providing method which uses a user terminal, a service providing
apparatus, and an authentication apparatus is disclosed. In the method,
authentication data is generated and encrypted by using an encryption key
which is stored in the user terminal. The encrypted authentication data is
transmitted from the authentication apparatus to the user terminal through
the service providing apparatus. The encrypted authentication data is
decrypted in the user terminal by using the encryption key. The decrypted
authentication data is returned to the authentication apparatus through
the service providing apparatus, and an authentication is executed in the
authentication apparatus by comparing the decrypted authentication data
transmitted from the user terminal with the authentication data before
encryption. The service providing apparatus provides a service to the user
in accordance with a result of the authentication.
