JP2528466B2 - IC card - Google Patents

Description

TECHNICAL FIELD The present invention relates to an IC card having a function of disabling the reading of data stored for a predetermined time and further erasing the data.

[Conventional technology]

Recently, an IC card in which an IC such as a CPU or a memory is built in the card has been proposed and is becoming popular. This IC card generally has a non-volatile programmable memory, and by storing various information as data in this memory, long-term data storage can be performed. Furthermore, the development of rewritable memory has progressed, and the data stored in the memory can be updated easily, making it possible to use the IC card itself for recycling.

The data stored in the memory of such an IC card is generally access-controlled by the CPU or an external device based on a built-in or external program.
In addition, depending on the application program stored in the ROM of this IC card, the CPU in the IC card may specify and manage the logical or physical recording position in the memory of the IC card according to the predetermined interpretation on the program. There are many things with different configurations. Therefore, in order to record the necessary information as data, a data storage area and position according to the content of the information are defined in advance in the memory of the IC card, and the application system specifies this data storage area and position to store the information. Will read and write.

[Problems to be solved by the invention]

However, in the conventional IC card having the above-described configuration, the data written in the data storage area in the nonvolatile readable / writable memory is stored until the data is erased or another data is overwritten. Therefore, confidential information is stored in the IC card, and if this IC card is lost, the confidential information will be
Since it is stored in the IC card, there is a problem that confidential information is likely to be stolen by a third party who picks up the IC card.

The present invention has been made to solve the above problems, and when storing highly confidential information, the IC is designed so that the information cannot be read out after being stored for a predetermined time and is further erased. Aim to get a card.

[Means for solving problems]

The IC card according to the present invention has a CPU and a non-volatile readable / writable memory, and stores in the memory time determination information for performing determination after a predetermined time has elapsed since the data was stored in the memory. An area is provided, and when the data stored in the memory is written, the unreadable time peculiar to the data is written in the time determination information storage area as a pair with the data, and the data stored in the memory When the data is read, the unreadable time forming a pair with the data is compared with the current time, the data is made unreadable based on the comparison result, and further erased.

[Action]

In the present invention, the unreadable time forming a pair with the data is compared with the current time at the time of reading to confirm whether or not the unreadable time has passed, thereby storing in the memory of the IC card after the unreadable time. The stored data can be made unreadable.

〔Example〕

FIG. 1 is a memory configuration diagram of a nonvolatile programmable memory in an IC card which is an embodiment of the present invention. In the figure, 1 is a data storage area, 1a is a normal data storage area, and 1b is an erase data storage area. The normal data storage area 1a has addresses A _{1 to} A _n-1 and the erase data storage area has addresses A _n to. It is assigned to a _m.

Normal data storage region 1a data D ₁ ~D _n-1 corresponding to each address A ₁ ~A _n-1 is stored. On the other hand, in the erased data storage area 1b, (A _n , A _{n + 1} ), (A _{n + 2} , A _{n + 3} ), ...
It is stored in the form of (A _k , A _{k + 1} ) paired with (A _m-1 , A _m ), and erase data SD _l is stored in address A _k and erase data SD is stored in address A _{k + 1. It} records the time T _{l at} which _l should be erased.

FIG. 2 is a flow chart showing a processing procedure at the time of writing data in the IC card having the memory configuration shown in FIG. 1. The write operation will be described below with reference to the same figure.
In step S1, if the input person specifies whether the data to be input by the input device etc. is erase data or normal data, and if it is designated as erase data, in step S2 the erase data storage area
The data _SD1 is written to the bump address A _{k of} 1b, and the erase time (unreadable time) T _l obtained by adding a predetermined storage time to the current time is written to the address A _{k + 1} in step S3.
On the other hand, if normal data is designated in step S1, free address A _i (i = 1 in the normal data storage area 1a is specified in step S4).
To n-1) as data D _i .

FIG. 3 is a flow chart showing a processing procedure at the time of reading data from the IC card having the memory structure shown in FIG. 1. The read operation will be described below with reference to the same figure. In step S11, it is determined whether the address A _j on the memory of the IC card 1 accessed by the CPU in the IC card is the normal data storage area 1a or the erase data storage area 1b, and this address A _j is the normal data storage area. If it is 1a, the contents of this address A _j are read in step S12, and the process is terminated. On the other hand, if the address A _j is the erase data storage area 1b, the erase time written in the address A _{j + 1} in step S13 is compared with the current time, and if the current time does not exceed the erase time, step S12 The contents of the address A _j are read with and the processing ends.

However, if the current time exceeds the erase time in step S13, the process moves to the next step S14 and the address A
The reading of the contents of _j is disabled (disabled), the contents of the address A _j are erased in step S15, and the process ends.

In this way, if the erase time is paired and stored in the erase data storage area 1b as the erase data such as confidential data, when the read time exceeds the erase time, the data is made unreadable and further erased. It has become. Therefore, even if the IC card is given to the third party, there is no possibility that the confidential data will be stolen by the third party if the erasing time has passed.

The processing shown in Fig. 2 and Fig. 3 is based on the application program stored in the ROM etc. in the IC card, and the CPU in the IC card
Can be done by In addition, time management can be performed by a configuration in which a clock function is built in the IC card, time information can be obtained from an external clock in the IC card, and the like.

Further, in this embodiment, the erase time is set as the erase data storage
Although it is stored in 1b, the write time is the erased data storage area.
It may be stored in 1b. In this case, the necessity of erasing erased data can be determined by comparing the current time with the write time + save time. Also, the storage time can be made variable. Further, without dividing the data storage area 1 into the normal data storage area 1a and the erased data storage area 1b, a method of adding information indicating whether or not the data is erased data to the data and storing it in the data storage area 1 is also conceivable.

〔The invention's effect〕

As described above, according to the present invention, by comparing the unreadable time such as the erase time with the current time at the time of reading, the data to be read forming a pair with the unreadable time indicates the unreadable time. You can check whether it has passed, and you can make the data unreadable after the unreadable time passes, so even if you store highly confidential information as data in the IC card, after the unreadable time passes, You can ensure confidentiality.

Furthermore, the data and the unreadable time form a pair, and by setting the unreadable time for each data unit, the unreadable time can be set to an appropriate time according to the confidentiality of each data.

[Brief description of drawings]

FIG. 1 is a memory configuration diagram of a nonvolatile programmable memory in an IC card which is an embodiment of the present invention, FIG. 2, FIG.
Each of the drawings is a flowchart showing a processing procedure in writing and reading of the IC card having the memory configuration shown in FIG. In the figure, 1 is a data storage area, 1a is a normal data storage area, and 1b is an erase data storage area. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] 1. An IC card having a CPU and a non-volatile readable / writable memory, wherein a time discriminating information storage area is provided in the memory for discriminating after a predetermined time has elapsed since the data was stored in the memory. When the data stored in the memory is written, the unreadable time peculiar to the data is written in the time discrimination information storage area as a pair with the data, and the data stored in the memory is read. An IC card characterized in that, at the time of outputting, the unreadable time forming a pair with the data is compared with the current time, the data is made unreadable based on the comparison result, and further erased. 2. The IC card according to claim 1, further comprising a normal information storage area for storing data that does not need to be made unreadable in the memory.