Abstract: An IC card internally stores two different PINs. Collation of these PINs sets the IC card having an internal data memory in different characterizing statuses. When coincidence occurs at the first PIN collation, data input to the data memory of the card is permitted. When coincidence occurs at the second PIN collation, data transfer is permitted. Accordingly, when important data is stored in the IC card and a plurality of persons handle the IC card, the data stored in the IC card can be prevented from being altered unauthorized.

Abstract: An IC including an EEP-ROM is formed on a semiconductor wafer. The IC also has exposed address pads connected to the address bus of the EEP-ROM, and exposed data pads connected to the data bus of the EEP-ROM. A test probe is brought into contact with these pads, thereby performing various tests on the IC. After the IC has been tested, the wafer is diced into IC pellets. The address pads are disconnected from the address bus and/or the data pads are disconnected from the data bus. For example, the edge portions of the IC pellet on which the address pads and/or the data pads are formed are cut by dicing from the remaining portion of the IC pellet. Thereafter, the connecting pads of the IC pellet are wire-bonded to leads, and the IC pellet is sealed with a resin. Finally, the sealed IC pellet is built in an IC card body.

Abstract: An IC card system according to this invention adopts a so-called intelligent-type IC card which has an internal power source of its own, can store designation data using the power source, and can display the storage content on a display unit. When the IC card is inserted in a terminal, the presence/absence of designation data is judged from the ON/OFF state of the power source of the card and, thereafter, a predetermined processing operation corresponding to the designation data is executed.

Abstract: When data is written in a predetermined memory area of a data memory in an IC card, a comparator checks whether the data before writing and data actually written in the data memory coincide. In the event of non-coincidence of the compared data, the data to be written is written in a different memory area of the data memory.

Abstract: Data unique to an IC card and encrypted unique data obtained by encrypting the unique data are previously stored in the IC card. The encrypted unique data is decrypted in an IC card terminal, to obtain decrypted data and the decrypted data and unique data stored in the IC card are compared on the side of the IC card and also in the IC card terminal, whereby the authenticity of both the IC card and IC card terminal is confirmed.

Abstract: When identification data stored in a predetermined area of a data memory in an IC card and data supplied from a card terminal coincide, the data stored in the data memory is substantially erased.

Abstract: A card holder inputs personal identification number (PIN') data as secret data and transaction data (AMT) in an LSI in an identification card through a keyboard. The LSI calculates encrypted data (SAN) in accordance with the input data (PIN' and AMT). The encrypted data (SAN) is shown by the card holder to a cashier at a point-of-sales (POS) terminal. The POS terminal performs authentication of the card and the card holder in accordance with the encrypted data (SAN).