IC card system and method for securing the system

Abstract: A control circuit (2) receives data input by the user through an operable monitor (1), attaches a data-encoding instruction to the input data, and supplies the instruction-attached input data to an IC card reader/writer (4). Upon receiving the instruction-attached input data, the IC card reader/writer (4) reads encoding key data stored in an IC card (3), thereby encoding the data and returning it to the control circuit (2). The control circuit (2), in turn, modifies the returned encoded data in the form of communicable data, and supplies a communication circuit (5) with the modified encoded data and an instruction to transmit the data. Upon receiving the modified encoded data and instruction, the communication circuit (5) transmits the modified encoded data to a host computer (6) via a communication line (7).

Description: This invention relates to an IC card system to be used as, for example, a transaction terminal installed in a bank for transmitting data input by the user to a host computer, using an IC card which stores encoding key data, and also to a method for securing the IC card system. In a transaction terminal installed in a bank, data input by the user, such as a password, an amount of money, etc., is encoded in light of security before it is transmitted to, for example, a host computer. The data input by the user is supplied to a control circuit, where it is encoded using key data stored in a hard disk or a semiconductor element under the control of the control circuit. There is a case where an IC card is used as a semiconductor element which stores encoding key data. To enhance security, it is necessary to exchange encoding key data with new one after it is used for a certain period of time. If the encoding key data is stored in a hard disk or a semiconductor element on an electric unit, very complicated means must be used to exchange it. There is a case where encoding is performed by use of an IC card which stores encoding key data and a reader device for reading the data. In this case, the encoding key data can be exchanged with new one very easily in a short time, since it can be done by exchanging only the IC card with another. However, the encoding key data which can be easily exchanged can be easily stolen and decoded, too. An IC card system according to the preamble of claim 1 or 2 is disclosed in EP 0 426 424 A2. It is the object of the invention to provide an IC card system protected from data decoding even when an IC card which stores encoding key data is stolen, and a method for securing the system. This object is achieved by an IC card system for transmitting data to a host computer using an IC card which stores encoding information according to claim 1 or 2, and a method according to claim 3 or 4, respetively. Further developments of the invention are given in the dependent claims. The invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which; FIG. 1 is a schematic view, showing an IC card system according to the invention; FIG. 2 is a block diagram, showing an IC card system according to a first embodiment; FIG. 3 is a block diagram, showing an IC card system according to a second embodiment; FIG. 4 is a perspective view showing an IC card reader/writer and an IC card according to a third embodiment which is an embodiment of the invention; FIG. 5 is a flowchart, useful in explaining the operation of taking the IC card out of the IC card reader/writer; and FIG. 6 is a view, showing an additional circuit structure employed in an IC card reader/writer according to a fourth embodiment which is an embodiment of the invention. Embodiments of an IC card system and their parts as well as their operations will be described in detail with reference to the accompanying drawings partly for explanation purposes only and partly as embodiments of the invention. FIG. 1 is a schematic view, showing an IC card system according to the invention. As is shown in FIG. 1, a mother board 10 as a control circuit board for controlling the overall system comprises an operable monitor 20 including an LCD monitor and a touch panel, a memory device 30 such as a hard disk (HDD), a floppy disk (FDD), etc., an IC card reader/writer 40 which inserts various IC cards, a serial IO (hereinafter referred to as "SIO") 60 connected to a printer 50 for outputting, for example, a journal, and a communication circuit 70 for communicating with a host (not shown). The IC card reader/writer 40 has sections corresponding to a credit IC card and an IC card as a stored value card (SVC), which are inserted by the user, and to an encoding IC card inserted by the bank clerk. FIG. 2 is a schematic view, showing the structure of an IC card system according to the first embodiment. As is shown in FIG. 2, the IC card system of the first embodiment comprises an operable monitor 1 to be operated by the user, a control circuit 2 for controlling the overall system, an IC card 3 storing encoding key data (encoding information), an IC card reader/writer 4 holding the IC card 3, a communication circuit 5 for communicating with an external device, and a host computer (hereinafter referred to simply as a "host") 6 connected to the communication circuit 5 via a communication line 7. The operation of the IC card system of the first embodiment will be described. First, the user selects contents of transaction from the menu on the monitor (input means) 1 and inputs his or her password, the amount of money, etc. through the monitor 1. These input data items are supplied to the control circuit 2. The control circuit (first instruction means) 2 supplies the user's input data items and an instruction to encode them, to the IC card reader/writer 4 inserting the IC card 3 which stores the encoding key data. The IC card reader/writer (encoding means) 4, in turn, reads the encoding key data from the IC card 3 to encode the user's input data items, and returns the encoded data items to the control circuit 2. Although in this embodiment, the IC card reader/writer 4 performs encoding, an encoding circuit may be provided in the IC card 3 to make the card perform encoding. The control circuit (second instruction means) 2 modifies the encoded data items in the form of communicable data, and supplies the communication circuit 5 with the modified encoded data items and an instruction to transmit them. The communication circuit 5, in turn, transmits the encoded user's data items to the host 6 via the communication line 7. As described above, in the first embodiment, data input by the user is encoded using encoding key data stored in an IC card, which means that the encoding key data cannot easily be stolen but can easily be changed. FIG. 3 shows an IC card system according to a second embodiment. The IC card system of this embodiment comprises an operable monitor 11 to be operated by the user, a control circuit 12 for controlling the overall system, which stores dedicated encoding key data (Key) A, an IC card 13 which stores dedicated encoding key data (Key) B, an IC card reader/writer 14 which stores the IC card 13, a communication circuit 15 for communicating with an external device, and a host 16 connected to the communication circuit 15 via a communication line 17. The operation of the IC card system of the second embodiment will be described. First, the user selects contents of transaction from the menu on the monitor (input means) 11 and inputs his or her password, the amount of money, etc. through the monitor 11. These input data items are supplied to the control circuit 12. The control circuit (first encoding means) 12 encodes the user's input data items using prestored encoding key data (second encoding information) A, thereby encoding data a. The circuit 12 then supplies the data a and an instruction to encode it, to the IC card reader/writer 14. Upon receiving the data a and the data-encoding instruction, the IC card reader/writer 14 reads encoding key data (first encoding information) B from the IC card 13 to encode the data a, and returns resultant data ab to the control circuit 12. Although in this embodiment, the IC card reader/writer 14 performs encoding, an encoding circuit may be provided in the IC card 3 to make the card perform encoding. The control circuit (decoding means) 12 decodes the data ab using the prestored encoding key data A, thereby decoding data b equivalent to data encoded by encoding the user's input data using the encoding key data B only. The circuit 12 then modifies the data b in the form of communicable data, and supplies the communication circuit 15 with the modified data b and an instruction to transmit the data b. Upon receiving the transmission instruction and the data b, the communication circuit (transmission means) 15 transmits, to the host 16 via the communication line 17, the user's input data encoded using the encoding key data B stored in the IC card 13. As described above, even if in the second embodiment, data transmitted through the communication line connecting the control circuit to the IC card reader/ writer is stolen, it cannot be decoded without any of the encoding key data items stored in the control circuit and the IC card. Thus, the second embodiment provides a high security by virtue of the two encoding key data items. FIG. 4 shows the appearances of an IC card 3 and an IC card reader/writer 4 according to a third embodiment which is an embodiment of the invention and is to be incorporated in the IC card system of the first embodiment shown in FIG. 2. When an eject switch 8 employed in the IC card reader/writer 4 is pushed, the IC card inserted therein is ejected. The operation of ejecting the IC card 3 from the IC card reader/writer 4 according to the third embodiment will be described with reference to the flowchart of FIG. 5. To take the IC card 3 out of the IC card reader/writer (holding means) 4 employed in the first embodiment, the eject switch 8 of the reader/writer 4 is pushed. When the eject switch 8 is pushed, the IC card reader/writer 4 supplies the control circuit 2 with an instruction to eject the card 3 (ST1). The control circuit 2, in turn, supplies the IC card reader/writer 4 with a control instruction to erase or rewrite the encoding key data stored in the IC card 3 (ST2). The IC card reader/writer (processing means) 4 erases or rewrites the encoding key data stored in the IC card 3 in accordance with the control instruction (ST3 and ST4). After erasing or rewriting of the encoding key data is completed, the IC card reader/writer 4 informs the control circuit 2 of the completion (ST5). The control circuit 2 then supplies the IC card reader/writer 4 with an instruction to eject the IC card 3 (ST6). Upon receiving the card-ejecting instruction, the IC card reader/writer (ejection means) 4 ejects the IC card 3 (ST7). As described above, in the third embodiment, the encoding key data stored in the IC card is erased or rewritten at the time of taking the IC card out of the IC card reader/writer, and therefore the encoding key data is prevented from being forged or stolen. FIG. 6 shows an additional circuit in an IC card reader/writer according to a fourth embodiment which is an embodiment of the invention and is employed in the IC card system of the first embodiment shown in Fig. 2. An IC card reader/writer 21 according to the fourth embodiment comprises an eject switch 22, a switch 23 which operates in synchronism with the eject switch 22, a power input terminal 24 for inputting a power to an IC 3a incorporated in the IC card 3, a power supply 25 for destroying the IC 3a of the IC card 3, a charging capacitor 26, an operation power-protecting diode 27, a ground terminal 28 for the IC 3a of the IC card 3, and a power supply 29 for operating the IC card 3. The charging capacitor 26 is provided for protecting the IC card reader/writer 21 when the power supply of the reader/writer is in the off-state. Further, the operation power-protecting diode 27 is provided for protecting a circuit for controlling the IC card 3 which is normally operating. The case of taking the IC card 3 out of the IC card reader/writer 21 will now be described. When the eject switch 22 of the IC card reader/writer (holding means) 21 is pushed, the switch 23 operable in synchronism with the eject switch 22 is turned on, thereby applying, to the power input terminal 24 of the IC card 3, the power of the power supply 25 which is sufficient to destroy the IC 3a. As a result, the IC 3a is destroyed. Then, the IC card reader/writer (eject means) 21 ejects the IC card 3. As described above, in the fourth embodiment, the IC of the IC card is destroyed when the IC card is taken out of the IC card reader/writer. Therefore, forgery or steal of encoding key data stored in the IC card is prevented.

Claims: An IC card system for transmitting input data to a host computer (6) using an IC card (3) which stores encoding information for encoding the input data to be transmitted, comprising holding means (4) for holding the IC card and for performing reading of data from the IC card and writing of data to the IC card, characterized by processing means (4) for erasing or rewriting the encoding information stored in the IC card when the IC card is to be taken out of the holding means, and ejection means (4) for ejecting the IC card after the processing means erases or rewrites the encoding information. An IC card system for transmitting input data to a host computer (6) using an IC card (3) having an IC (3a) which stores encoding information for encoding the input data to be transmitted, comprising holding means (21) for holding the IC card and for performing reading of data from the IC card and writing of data to the IC card, characterized by application means (25) for applying, to the IC of the IC card, a voltage large enough to destroy the IC, when the IC card is to be taken out of the holding means, and ejection means (21) for ejecting the IC card from the holding means after the IC of the IC card is destroyed by the voltage from the application means. A method of securing an IC card system for transmitting input data to a host computer (6) using an IC card (3) which stores encoding information for encoding the input data to be transmitted, comprising the steps of erasing or rewriting the encoding information stored in the IC card when the IC card is to be taken out of a holding means (4) that is adapted to hold the IC card and to perform reading of data from the IC card and writing of data into the IC card and ejecting the IC card from the holding means after the encoding information is erased or rewritten. A method of securing an IC card system for transmitting input data to a host computer (6) using an IC card (3) having an IC (3a) which stores encoding information for encoding the input data to be transmitted, comprising the steps of: applying, to the IC of the IC card, a voltage large enough to destroy the IC, when the IC card is to be taken out of a holding means (21) that is adapted to hold the IC card and to perform reading of data from the IC card and writing of data into the IC card and ejecting the IC card from the holding means after the IC of the IC card is destroyed by the voltage.

Inventors: KAWAGISHI TOSHIYUKI, KUROKAWA MASANORI, KAWAGISHI, TOSHIYUKI, KUROKAWA, MASANORI
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1998
Main classification: G06K19
IPC codes: G07F7, G09C1, G06K17, G06F21, H04L9