Importance

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Abstract

In an authentication method between an IC card and a terminal unit, authentication is performed without an authentication code or an address therefor being transmitted directly between the two devices so as to assure the security of the authentication operation. Both of the IC card and the terminal unit include multiple authentication codes each code having a corresponding time data item, and an encryption algorithm. In one of the IC card and the terminal unit, one of the authentication codes is selected, and the selected authentication code is encrypted according to the encryption algorithm. The encrypted authentication code is transmitted to the other device as authentication data. The time data corresponding to the selected authentication code is transmitted to the other device as a time interval between commands or signals. In the other device, the authentication code obtained from the time data is encrypted according to the encryption algorithm to generate authentication data. The generated authentication data is compared with the authentication data sent from the other device.

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First Claim