JP3835753B2 - IC card - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an IC card and information processing thereof, and more particularly to data protection in a data writing process for a read / write nonvolatile memory of an IC card.
[0002]
[Prior art]
In recent years, IC cards have been used in various fields. Each IC card includes at least a read-only nonvolatile memory and a read / write nonvolatile memory. Data is written to and read from the readable / writable nonvolatile memory as needed. The data write processing time when writing data is required to be about 3 ms to 5 ms.
[0003]
As a special case, it is assumed that the power supplied to the IC card is lowered or cut off during the writing process. In that special case, the writing process may not be completed, and the data in the read / writeable non-volatile memory area to be written may be destroyed.
[0004]
In order to avoid this problem, when the writing process has not been completed in the past, the data indicating the data destruction in the write target area and / or the writing process of the IC card by the host apparatus is sent to the host apparatus that sent the write data to the IC card. Is notified to the host device via the interface of the IC card.
[0005]
[Problems to be solved by the invention]
In the above-described conventional method, the host device when the writing process has failed and the host device that is trying to rewrite do not necessarily match, so there is a risk that the data used for the rewriting process by the host device is different. .
[0006]
Therefore, the technical problem of the present invention is that the IC card performs the write-back process to protect the data and the write-back process so that the rewrite process by the host device that may write erroneous data is not required. It is an object to provide an IC card having a function of notifying a higher-level device of having performed.
[0007]
[Means for Solving the Problems]
According to the present invention, in an IC card comprising an arithmetic processing unit, a read-only nonvolatile memory, a readable / writable nonvolatile memory, and an interface unit for exchanging data with a host device as a communication target terminal, When writing the data received from the host device to a predetermined area of the readable / writable nonvolatile memory, the arithmetic processing unit separates the data already written in the predetermined area from the readable / writable nonvolatile memory. A function for writing to the area, a function for storing write processing information indicating the data length and head address of the received data in the memory management unit of the readable / writable nonvolatile memory, and the received to the predetermined area Data and the feature data (checksum) calculated from the received data With writing, IC card and having a function of writing information indicating that rewriting of data of the predetermined area can be obtained.
[0008]
According to the invention, the arithmetic processing unit refers to the start address and the data length of the write processing information stored in the memory management unit when the IC card is activated, and writes it in the predetermined area. The feature data is calculated based on the received data, and the feature data is compared with the feature data (checksum) written in the prescribed area, whereby the received data for the prescribed area is compared. It is possible to obtain an IC card characterized by having a function of detecting that the writing of has not been completed normally.
[0009]
According to the present invention, the arithmetic processing unit detects that the received data has not been written to the predetermined area, and then writes the data written to the other area in the predetermined area . Is written (write back), and write-back information indicating that the write-back has been performed is written, and the higher-level device is notified that the writing of the received data to the predetermined area has not been completed normally. An IC card having a function is obtained.
[0010]
Further, according to the present invention, the arithmetic processing unit is a write indicating that the write-back is performed when the host device performs processing such as read, write, and collation on the data written back to the predetermined area. By referring to the return information, an IC card having a function of notifying the host device that the data in the predetermined area is the data written back can be obtained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0012]
FIG. 1 is a block diagram showing a schematic configuration of an IC card according to an embodiment of the present invention. As shown in FIG. 1, on an IC chip 1 mounted in an IC card according to the present embodiment, an interface 6 for exchanging data with a host device 7, an arithmetic processing unit 5 for processing a control program, and volatile A memory (RAM) 2, a read-only nonvolatile memory (ROM, first nonvolatile memory) 3 for storing a control program, and a read / writeable nonvolatile memory (EEPROM, second memory) for storing write or rewrite data Non-volatile memory) 4.
[0013]
In this embodiment, the read-only memory (EEPROM) 4 that can be electrically written and erased is used as the read / write nonvolatile memory. However, a ferroelectric nonvolatile memory may be used.
[0014]
The read-only nonvolatile memory 3 stores a control program for performing a data write process, a data write incomplete detection process, and a data write-back process. The volatile memory 2 and / or the read / write nonvolatile memory 4 Can also be stored.
[0015]
FIG. 2 is a structural diagram showing the readable / writable nonvolatile memory 4 of the IC card of FIG. The readable / writable non-volatile memory 4 includes a data write area 11, a data string 12 indicating the end of data, a data feature data (checksum) 13, Write-back information 14 is provided. In addition, the memory management unit 9 that holds the write processing information indicating the data length 15 and the start address 16 of the data to be newly written, and the data in the write target area 8 are written before the data is written in the write target area 8 The evacuation memory area 10 to be held in the IC card is provided.
[0016]
Next, with reference to FIG. 3 in addition to FIGS. 1 and 2, the data writing process, the data writing incomplete detection process, and the data writing back process for the IC card will be described. In the present embodiment, a write command is used as a data string to be written and a read command is used as a data string not to be written.
[0017]
1) When a power supply voltage is supplied from the host device 7 and an initial response operation is requested (S1 in FIG. 3), the IC card makes an initial response to the host device (S2 in FIG. 3) and then remains in a reception waiting state. . At this time, the data string 12 indicating the end of data is a normal data string, the data feature data (checksum) 13 is a normal checksum, and the data writeback information 14 indicates no writeback.
[0018]
2) When reading from the write target area 8 by a read command (S3 in FIG. 3), the IC card refers to the data write-back information 14 and detects that the data is not written back, and then the host device Is notified of the command processing result (S5 in FIG. 3).
[0019]
3) When writing to the write target area 8 by a write command (S6 in FIG. 3), the IC card writes the data written in the write target area 8 to the save memory area 10 and then writes a new one Write the data length 15 and head address 16 of the data to the memory management section 9, then write the data (A) to the write target area 8, and calculate from the data string 12 indicating the end of data at the end of the data and the data (A) The feature data (checksum) 13 and the data write-back information 14 are written (S7 in FIG. 3).
[0020]
4) When a power supply voltage drop occurs during the writing process (S8 in FIG. 3), the writing process is not completed (S9 in FIG. 3), the data string 12 indicating the end of data, and the characteristic data (checksum) of the data Reference numeral 13 indicates an abnormality.
[0021]
5) When the power supply voltage is resupplied from the host device 7 and an initial response operation is requested (S10 in FIG. 3), the IC card receives the start address 16 of the write processing information shown in the memory management unit 9 and the write processing information. Referring to the data length 15 , the write target area 8 written last time is verified. That is, by calculating the feature data based on the written data and comparing it with the written feature data (checksum) 13, it is detected that the writing has not been completed normally (see FIG. 3). S11). After that, the IC card writes the data written in the save memory area 10 back to the write target area 8, changes the data write-back information 14 to “write back”, and then writes the previous data to the host device. After an initial response (S13 in FIG. 3) indicating that the process has not been completed normally, it remains in a reception waiting state.
[0022]
6) When reading the write target area 8 again by the read command (S14 in FIG. 3), the IC card refers to the data write-back information 14 and detects that the data has been written back ( In S15 of FIG. 3, the command processing result and the fact that the data is the written back data are notified to the host device (S17 of FIG. 3).
[0023]
7) When writing to the write target area 8 again by the write command (S18 in FIG. 3), the IC card writes the data written in the write target area 8 to the save memory area 10 and then writes the data. Data (A) is written in the target area 8, and a data string 12 indicating the end of data at the end of the data, feature data (checksum) 13 calculated from the data (A), and data write-back information 14 are written (FIG. 3). S19), the command processing result is notified to the host device (S20 in FIG. 3).
[0024]
8) When reading the write target area 8 again by the read command (S21 in FIG. 3), the IC card refers to the data write-back information 14 and detects that the data has not been written back. The command processing result is notified to the host device (S23 in FIG. 3).
[0025]
Needless to say, various modifications are possible as described below.
[0026]
For example, by verifying the data string 12 indicating the end of data and calculating the feature data based on the written data and comparing it with the written feature data (checksum) 13, the writing is completed normally. The function of detecting that it has not been performed can be realized by a software program. Of course, the IC card has a function of notifying that writing has not been completed normally when writing has not been completed, but this function may be realized by a software program.
[0027]
The data length to be written in the write target area 8 can be the same as the data length of the save memory area 10, and the length can be arbitrarily set.
[0028]
Further, a plurality of write target areas may exist. In this case, the same number of memory management units 9 as the write target areas 8 and one save memory area 10 having the same data length as the maximum write target area 8 are required. is there.
[0029]
【The invention's effect】
As described above, according to the present invention, since the IC card itself writes back the unwritten data area, data protection that does not require rewrite processing by a higher-level device that may write erroneous data. An IC card having a function can be provided.
[0030]
Also, an IC card having a function of notifying the host device that data has been written back when data write back processing due to a drop in power supply voltage can be provided.
[0031]
Furthermore, by adding a data string indicating the end of data and data feature data (checksum) to the data to be written to the readable / writable nonvolatile memory, even when at least a 1-bit data write failure occurs, This effect is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of an IC card according to an embodiment of the present invention.
2 is a structural diagram of a readable / writable nonvolatile memory in the IC card of FIG. 1. FIG.
FIG. 3 is a flowchart showing data protection processing in the IC card of FIG. 1;
[Explanation of symbols]
1 IC chip 2 Volatile memory (RAM)
3 Read-only nonvolatile memory (ROM)
4 Read / write non-volatile memory (EEPROM)
5 arithmetic processing unit 6 interface 7 host device 8 write target area 9 memory management unit 10 save memory area 11 data write area 12 data string indicating data end 13 data characteristic data (checksum)
14 Data write-back information 15 Data length 16 Start address

Claims (4)

In an IC card including an arithmetic processing unit, a read-only nonvolatile memory, a readable / writable nonvolatile memory, and an interface unit that exchanges data with a host device that is a communication target terminal, the arithmetic processing unit includes a host when writing data received from the apparatus to a predetermined region of the read writable nonvolatile memory, function of writing the data already written in the predetermined area to another area of the read writable nonvolatile memory, A function of storing write processing information indicating a data length and a leading address of the received data in a memory management unit of the readable / writable nonvolatile memory; and the received data in the predetermined area and the received Write the feature data (checksum) calculated from the data and IC card and having a function of writing information indicating that rewriting the data of the predetermined area. 2. The IC card according to claim 1, wherein the arithmetic processing unit refers to the start address and the data length of the write processing information stored in the memory management unit when the IC card is activated, and The feature data is calculated on the basis of the received data written in the data, and the feature data is compared with the feature data (checksum) written in the predetermined region, whereby the reception for the predetermined region is performed. An IC card characterized by having a function of detecting that writing of the completed data has not been completed normally. 3. The IC card according to claim 2 , wherein the arithmetic processing unit detects that the received data has not been written to the predetermined area, and then writes the data to the predetermined area. Write back data and write back information indicating that the write back has been performed, and further confirm that writing of the received data to the predetermined area is not normally completed in the host device. An IC card having a notification function. 4. The IC card according to claim 3 , wherein the arithmetic processing unit has performed the write-back when a host device performs processing such as reading, writing, and collation on the data written back to the predetermined area. An IC card having a function of notifying a host device that the data in the predetermined area is data written back by referring to the write-back information shown.

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