An image processing apparatus provided with a biological information sensor receives an authentication request including a verification parameter from a service providing system, transmits the verification parameter to an information processing apparatus provided with an authentication module for biometric authentication, and a tamper-resistant storage device configured to store a user's biological information required when an authentication process is performed by the authentication module and a private key generated with respect to the biological information, transmits the biological information acquired by the biological information sensor using an encryption technique to the information processing apparatus, receives signature data, created using the private key extracted when biometric authentication based on the transmitted biological information has succeeded and the verification parameter, from the information processing apparatus, and transmits the signature data to the service providing system.