To improve safety in providing information from a server by providing a technology for effectively preventing the leakage of biological information whose secrecy is high to a communication network.

The server S transmits keys KUtoUT and KUTtoU for registration generated at random by the server (S) to a terminal UT in response to a request from the terminal UT. The terminal UT and the server S mutually authenticates the equipment of the other party through a communication network N. When this mutual authentication is successful, the keys KUtoUT and KUTtoU for registration are encrypted and transmitted from the server S to the terminal UT. Then, the keys KUtoUT and KUTtoU for registration are decoded by the terminal. The key KUTtoU for registration being one of the keys for registration obtained by this composition is presented to the user U, and the user U is urged to input the KUTtoU for registration and the biological information of the user U to the user terminal UT. Then, whether or not the KUTtoU inputted by the user U is matched with the key KUtoUT obtained by the above composition is verified.