JPH0743881B2 - Optical card data falsification check method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical card data tampering check system, and more particularly to an optical card tampering check system suitable for easily performing tampering check of card data in an optical card. .

[Conventional technology]

Conventionally, an optical card (optical memory card) has been developed as a card capable of recording information with a laser beam and optically reproducing the recorded information with a CCD or a laser beam. Such optical cards are currently classified into a write once type that allows additional recording and a read only ROM type.
It cannot be erased or rewritten like a magnetic card. However, even the Write Once type has a large recording capacity, so that new information can be added and written. On the other hand, the ROM type is suitable for the purpose of distributing a large amount of the same contents.

To describe data recording / reproduction in an optical card in more detail, data recording is performed by exposing a laser beam to the card surface (recording medium surface) and punching holes by the heat generated there. Reproduction is performed by shining CCD or laser light and detecting the reflected light intensity with or without holes. The size of this hole is about 5 μm.

In the optical card as described above, the following method is conceivable when performing data check. That is, as described in Japanese Patent Application Laid-Open No. 57-188159, there is a method of checking the validity of read data by a combination of a plurality of check methods by having a plurality of BCCs (block check characters), and As described in Japanese Patent Publication 57-140050, the total value of certain items related to the content of data is calculated,
This is used as check data, and at the time of data check, the same total value is obtained from the data and collated with the check data.

[Problems to be solved by the invention]

In the above conventional technology, there is a tendency to increase the reliability of data by complicating any data check method,
There is a problem in that the burden of creating the check data and the check circuit increases.

An object of the present invention is to solve such conventional problems and to provide an optical card data tampering check system capable of easily performing data tampering check and validity check in an optical card.

[Means for solving problems]

In order to solve the above-mentioned problems, in the present invention, data is recorded by making a hole in a recording medium by irradiating a laser beam, and the presence or absence of the hole is optically detected by the strength of reflection of the irradiating laser beam. When data is recorded on the optical card, it is impossible to erase the data (bits) once the data is reproduced and the holes cannot be erased once the data has been tampered with. The tampering check data, which is the inverted data, is recorded together with the above-mentioned record data, and when the data is read, it is checked whether or not each bit of the data part and the tampering check data part has an inversion relation, thereby recording data It is characterized by checking for tampering.

[Action]

In the present invention, when data is recorded on the optical card, the recorded data and the check data in which all bits are inverted are recorded together with the data. The optical card is a method of making a hole in the recording medium with laser light, and at the time of reading, it is a method to read the recorded data by optically detecting the presence or absence of the hole by the strength of reflection of the irradiation laser light, and the bit that has been once made is reproduced. Since it is impossible, data tampering is possible only in the direction of making a hole. Therefore, if the data on the optical card has been tampered with by a third party, both the data and the corresponding bit of the check data are in a perforated state, and it is known that the data has been tampered with. That is, the tampering check of the recorded data on the laser card can be realized only by checking that all the bits of the recorded data and all the bits of the check data have an inversion relationship.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of an optical card to which the present invention is applied. Here, 12 is an optical card, 13 is an optical card recording unit for recording data, 14 is a data unit for directly recording write data, and 15 is a check data unit for recording data in which write data is bit-inverted.

FIG. 1 is a diagram for explaining an optical card data tampering check system according to an embodiment of the present invention. (A) shows a data write operation, and (b) shows a data read operation. The writing and reading operations are performed by a card reader / writer or the like.

In FIGS. 1 (a) and 1 (b), 1 is write data to the optical card, 2 is read data from the optical card, 3 is an error detection signal, and 10 is all bits of the write data 1, 1.0
A data inverting mechanism for inverting, 11 is an optical card writing mechanism for writing the write data 1 and the check data created by the data inverting mechanism 10 to the optical card recording unit 13 in the optical card 12, 12 is an optical card, and 16 is A laser card reading mechanism for reading data from the optical card recording unit 13 in the optical card 12, 17 is a reversal relation in which the data unit 14 read by the optical card reading mechanism 16 and the checking data unit 15 are all 0s and 1s for all bits. Is an equivalence detection mechanism that checks whether or not These mechanisms are mechanisms incorporated in a card reader / writer (not shown).

First, regarding data recording on an optical card, FIG. 1 (a)
Will be explained.

When data is recorded on the optical card, check data in which all bits of the write data 1 are inverted by 1,0 is created by the data inversion mechanism 10 and is written to the optical card recording unit 13 in the optical card 12 together with the write data 1. Write by the optical card writing mechanism 11. In this case, the optical card recording unit 13 is
And the check data portion 15 created by the data inverting mechanism 10 are recorded separately. FIG. 3 shows an example of the recorded data when the data length is 8 bits. Third
As shown in the figure, between the data section 14 and the check data section 15, all bits are recorded in the data section 14 and the check data section 15 so that all bits are in an inverted relationship of 0 and 1. In order to tamper with data in this state, it is not possible to reproduce the data bit that has a hole once due to the recording method of the optical card, so data tampering can only be done in the direction of making a hole, so a bit of 0 (not a hole) There is no choice but to set to 1 (perforated state) (In the above, 0 is not perforated, 1
Has a hole, but the reverse is also possible). That is, when data is tampered with, the 0, 1 inversion relationship of all bits between the data part 14 and the check data part 15 is broken, and by checking this relationship, it is determined whether or not there is tampering. Can be checked.

Next, regarding tampering check of optical card data, first
This will be described with reference to FIG.

When reading the write data recorded in the optical card 12, the data section is read from the optical card recording section 13 by the optical card reading mechanism 16.
14 and check data section 15 are read together, and equivalence detection mechanism
17 is provided with both the data part 14 and the checking data part 15. The equivalence detection mechanism 17 checks whether or not all the bits of the received data part 14 and the check data part 15 have the same value for each bit, and even if one bit has the same value (1, 1 or 0,
If there is 0), the error detection signal 3 is generated as a tampering occurrence or a read error occurrence. Equivalency detection mechanism
According to 17, if all the bits of the data part 14 and the check data part 15 have different values (a state in which 1 and 0 are inverted) corresponding to each bit, the error detection signal 3 is not generated and the read data 2 is generated. Is equivalent to the write data 1 at the time of writing,
It means normal data that has not been tampered with.

As described above, in the present embodiment, it is possible to easily reproduce the data in the optical card by utilizing the fact that the bit having the hole once cannot be reproduced due to the recording method of the optical card, and the falsification of data is possible only in the direction of making the hole. You can check the falsification of data.

〔The invention's effect〕

As described above, according to the present invention, the tampering check and the validity check of data can be easily performed in the optical card.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an optical card data tampering check system showing an embodiment of the present invention, FIG. 2 is a configuration diagram of an optical card which is the subject of the present invention, and FIG. 3 is an implementation of the present invention. It is a figure which shows the mode of the data recorded on the optical card in an example. 1: Write data, 2: Read data, 3: Error detection signal,
10: Data inversion mechanism, 11: Optical card writing mechanism, 12: Optical card, 13: Optical card data recording part, 14: Data part, 15: Check data part, 16: Optical card reading mechanism, 17: Equivalence detection mechanism .

Claims (1)

[Claims] 1. Data recording is performed by making a hole in a recording medium by irradiating a laser beam, and the presence or absence of the hole is optically detected by the strength of reflection of the irradiating laser beam to reproduce the data. When opened, the data (bits) cannot be erased, and tampering with data is possible only in the direction of making holes. For tampering checking, when recording data, the recorded data and all bits of the recorded data are reversed. By recording the data together with the above-mentioned recorded data and checking whether or not each bit of the data part and the tampering check data part has an inversion relation when reading the data,
Optical card data tampering check method characterized by checking tampering of recorded data.