JP2000076605A - Method of recording data for magnetic card and method of discriminating authenticity for magnetic card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a data recording method for a magnetic card, to which a not-easily-soluble counter measure is applied in preventing forgery and alternation, and also an authenticity discriminating method for a magnetic card. SOLUTION: In writing data in a recording layer in the depth layer of a magnetic card using the F2F method, a modulation pulse regulated by the cryptographic key of a cryptographic key generator 25 is outputted from a modulation pulse generator 26, and is recorded on a recording layer on the surface layer of the magnetic card. In reproduction, the modulation pulse is always reproduced synchronously with the reading of data and superposed on the F2F output of an F2F waveform generator 22. In addition, this modulation pulse is so constructed as to be a pulse of small energy so as to impart strain in an unnoticeable degree even if the F2F waveform is observed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording data on a magnetic card and a method for determining the authenticity of the magnetic card, which make it extremely difficult to forge or alter the magnetic card for unauthorized use.

[0002]

2. Description of the Related Art Magnetic cards have come to be used for prepaid cards and coupons. Along with this, forgeries that make the same thing including the recording medium material of the magnetic card, and alterations made by diverting all or a part of the magnetic card are performed, and various preventive measures are taken. .

For example, Japanese Patent Application Laid-Open No. 63-34522 discloses a method and apparatus for writing and reading data on a magnetic card. In this example, a minute component is superimposed on the waveform as a modulation component in the amplitude direction, and the authenticity of the amplitude-modulated waveform is determined based on the fact that normal reading cannot be performed.

However, in this example, when the normal medium is read by another device, the superimposition of the waveform can be recognized by visually observing the reproduced waveform. Once the waveform shape is known, the same superimposition can easily be inferred by those skilled in the art, and it has been difficult to completely prevent fraud.

[0005] As described above, none of the conventional authenticity discrimination methods can be said to be a fundamental countermeasure, and in fact, any countermeasures have been clarified and neglected.

[0006]

As described above, the struggle between countermeasures for preventing forgery and alteration and techniques for elucidating these countermeasures has continued indefinitely, and a strong countermeasure has been eagerly desired.

The present invention has been made in view of the above points, and has as its object to provide a magnetic card data recording method and a magnetic card authenticity discriminating method in which preventive measures which cannot be easily clarified are taken.

[0008]

A data recording method for a magnetic card according to the present invention uses a magnetic card using the F2F system in which one value of binary data is recorded at twice the frequency of the other value. In the data recording method, a magnetic card having a multilayer recording layer is used, the binary data is recorded on a deep recording layer, and the binary data is recorded on a surface recording layer according to a predetermined pulse arrangement. A modulated pulse having a small energy to be subjected to analog modulation is recorded without giving a significant distortion to each waveform at the time of recording and reproduction.

Further, the method for determining the authenticity of a magnetic card according to the present invention uses a F2F method in which one value of binary data is recorded at twice the frequency of recording the other value, and the deep recording of the magnetic card is performed. A modulation pulse having a small energy for recording the binary data in a layer and applying analog modulation to the binary data in accordance with a predetermined pulse arrangement on a surface recording layer without giving significant distortion to individual waveforms at the time of recording and reproduction. A magnetic card authenticity determination method for determining whether the magnetic card is a magnetic card or not, wherein data recorded on the magnetic card is reproduced, and a modulated wave and an unmodulated wave based on the predetermined pulse sequence are reproduced from the data. Of the same number is extracted, and these are A / D
After the conversion, the normalized magnetic card is determined to be a normal magnetic card only when the difference after averaging the plurality of modulated waves and the unmodulated waves is within a predetermined value.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A data recording method for a magnetic card according to the present invention is such that when performing normal F2F (described later) saturation recording, a pulse-like modulation component having a small energy is superimposed and a simple F2F waveform is obtained. A small analog modulation (actually waveform distortion) of a level that cannot be seen is applied.

In order to determine whether or not the magnetic card has been recorded in this manner, for example, a modulated wave and an unmodulated wave are recorded in a portion where 100 waves of F2F are continuous, and an arrangement thereof is performed. (Using an encryption key) is also recorded in another part of the same medium. The card reader normalizes and extracts the modulated wave and the unmodulated wave based on the arrangement information and performs an averaging process. When a predetermined difference signal is obtained, the card reader is determined to be a normal magnetic card.

Here, the above-mentioned F2F modulation method will be described with reference to FIGS.

FIG. 5A is a block diagram showing the configuration of the writing means. Reference numeral 1 denotes an input terminal to which binary data is applied. 2 is an F2F waveform generation circuit, 3 is a driver, and 4 is a magnetic head for writing.

FIG. 5B is a block diagram showing the construction of the reading means, wherein 11 is a magnetic head for reading, 12 is an amplifier, 13 is a pulse detector, 14 is a synchronization signal generator,
5 is a decoder and 16 is an output terminal.

FIG. 6 is a waveform diagram of a main part for explaining the operation. Hereinafter, referring to FIG. 6, FIG.
The operation (b), that is, the F2F method will be described.

In FIG. 5A, when binary data is applied to the input terminal 1, the F2F waveform generation circuit 2 receiving the binary data outputs "0" when the input binary data is "1". Is converted into a recording code string at twice the frequency as compared with the case of. This relationship is as shown in FIG. This method is called the F2F method, and is widely used because the influence of the resolution is small, the recording density is relatively large, and the configuration is simple. Conversely, recording may be performed at twice the frequency when the binary data is "0" as compared with the case where the binary data is "1".

In FIG. 5B, when the data recorded in FIG. 5A is read by the read magnetic head 11, a reproduced signal having a waveform as shown in FIG. 6 is obtained. The pulse detector 13 detects whether or not there is a detection pulse within a predetermined time zone by using a synchronization signal from the synchronization signal generator 14 which is generated in synchronization with the basic period of the binary data. The decoder 15 reproduces the binary data from the detected pulse train, and outputs the decoded data from the output terminal 16.

The outline of the F2F system has been described above. The present invention uses the F2F system. Hereinafter, embodiments of the present invention will be described.

[0019]

FIG. 1 is a block diagram showing an example of the configuration of an apparatus for carrying out a data recording method for a magnetic card according to the present invention. In this figure, 21 is an input terminal, 22 is an F2F waveform generating circuit, 23 is a head driver, and 24 is a magnetic head for writing, which has the same configuration as that of the conventional example of FIG. 25 is an encryption key generator, 26 is a modulation pulse generator, 27 is an F2F waveform generation circuit, 28 is a head driver, and 29 is a magnetic head for recording modulation pulses.

FIG. 2 is a block diagram showing an example of the configuration of an apparatus for implementing the magnetic card authenticity discrimination method of the present invention. In this figure, 31 is a magnetic head for reproduction, 32 is a preamplifier, 33 is an F2F demodulation circuit, 34 is an output terminal,
35 is an A / D converter, 36 is a normalizing circuit, 37 is an averaging circuit for modulated / unmodulated waves, 38 is an authenticity discriminating circuit,
Reference numeral 9 denotes a magnetic head for reproducing modulated pulses, 40 denotes a preamplifier, and 41 denotes an F2F demodulation circuit.

FIG. 3 shows a magnetic card 100 used in the present invention.
1 is a cross-sectional view showing an example of a substrate 101 such as PET.
2 is a deep recording layer; 103 is a surface recording layer;
It is made of a magnetic material having a smaller coercive force than 02. 104
Is a layer to be worn and is made of a magnetic material, but the coating layer 104 is not necessarily made of a magnetic material.

Next, the operation will be described.

<Write Operation> In FIG.
The fact that the binary data applied to 1 is recorded on the recording layer 102 of the magnetic card 100 by the magnetic head 24 indicates that F2
This is the same as described for the F method.

The modulation pulse generator 26 is the encryption key generator 2
5 generates a modulation pulse in accordance with the pulse sequence indicated by the encryption key from the recording layer 103 of the magnetic card 100.
To record. Therefore, when the data of the recording layer 102 is reproduced as described later, the modulated pulse of the recording layer 103 is also reproduced at the same time.
Is added to the recording code string which is the output of. That is, amplitude modulation is performed.

That is, as shown in FIG. 4A, a modulated pulse P having a small energy as shown by a dotted line is compared with a binary data pulse P1 ("1") shown by a solid line.
Add 2. The modulation pulse P2 is a binary data pulse P
Although it is synchronized with one cycle, where to add it in the pulse train is determined by the instruction of the encryption key. The energy of the modulation pulse P2 indicated by the dotted line is small enough that even if the reproduced waveform of each pulse P1 of the binary data is viewed at the time of reproduction, no significant distortion is found. The height of the waveform of the pulse P1 shown by the solid line corresponds to the current value written to the recording layer 102, and the waveform height of the modulated pulse P2 shown by the dotted line corresponds to the current value written to the recording layer 103. further,
The data of the encryption key from the encryption key generator 25 is also converted into binary data by the F2F waveform generation circuit 27, applied to the magnetic head 29 via the head driver 28, and stored in another place of the magnetic card 100.

<Authentication Judgment Operation> In the present invention, data is recorded on the deep recording layer 102 while a modulation pulse is applied to the surface recording layer 103 of the magnetic card 100 as described above. Even if it is altered or forged, the authenticity can be determined as follows.

From the target magnetic card to the magnetic head 31
In the same manner as in the conventional F2F system, the data is reproduced, amplified by the preamplifier 32, added to the F2F demodulation circuit 33, obtained binary data here, and output from the output terminal 34. On the other hand, the data of the encryption key (recorded by the magnetic head 29 in FIG. 1) is reproduced by the magnetic head 39 and the pre-amplifier 40 sets the data to a required level.
An array of modulation pulses input to the demodulation circuit 41, that is, an encryption key used when data is written to the magnetic card 100 is obtained.

Separately, the output of the preamplifier 32 is digitized by an A / D converter 35 while being sampled, normalized by a normalizing circuit 36, and input to a next-stage modulated / unmodulated wave averaging circuit 37. Based on the encryption key output from the F2F demodulation circuit 41, the normalized data is extracted from a plurality of equal numbers of modulated waves and unmodulated waves. And if the value is within a predetermined range, it is determined that the magnetic card is normal and an output indicating that the card is normal is output. Otherwise, output an error. That is, a value corresponding to the area of the waveform reproduced by the magnetic head 31 is obtained for a plurality of modulated waves and non-modulated waves, and is discriminated from the difference.

In this manner, it is possible to easily determine whether or not the magnetic card 100 has been created by a regular procedure.

[0030]

The data recording method for a magnetic card according to the present invention is a method for recording data on a magnetic card using the F2F system in which one value of binary data is recorded at twice the frequency of the other value. Wherein the magnetic card has a multilayer recording layer, and the deep recording layer has an analog waveform according to a predetermined pulse arrangement without giving significant distortion to individual waveforms at the time of recording / reproducing the binary data. Modulation pulses with a small energy to be modulated are recorded, so the data on the magnetic card is reproduced in an attempt to forge or falsify, and even if the waveform is observed, the energy of the modulation pulse gives a significant distortion to the reproduced waveform. Since it is not so small, it is not clear whether a modulated pulse has been added no matter how much of the reproduced waveform. Therefore, forgery and falsification are almost impossible.

Further, the method for determining the authenticity of a magnetic card according to the present invention uses the F2F method in which one value of binary data is recorded at twice the frequency of the other value and the deep recording of the magnetic card is performed. The above-described binary data is recorded on a layer, and a small energy modulation is performed on the surface recording layer according to a predetermined pulse arrangement without applying any significant distortion to each waveform at the time of recording / reproducing the binary data. A magnetic card authenticity determination method for determining whether a magnetic card is a pulse-recorded magnetic card, comprising reproducing data recorded on a deep recording layer and a modulated pulse recorded on a surface recording layer of the magnetic card. A plurality of modulated waves and unmodulated waves are extracted from the same number based on the predetermined pulse array, and
After performing the / D conversion, normalization is performed, and only when the difference after averaging the plurality of modulated waves and the non-modulated waves is within a predetermined value, a normal magnetic card is determined. Since the difference is a level of minute modulation that can be extracted only after the averaging process, a. The invisibility is very high and the presence of modulation is unknown.

B. Even if the modulation is known, the S / N is poor in single wave units and analog copying is difficult.

C. Unless the modulation method (pulse injection method and its position and width) is known, the same modulated waveform cannot be written. It is effective for copy protection.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of the configuration of an apparatus for implementing a magnetic card data recording method according to the present invention.

FIG. 2 is a block diagram showing an example of the configuration of an apparatus for implementing the magnetic card authenticity determination method of the present invention.

FIG. 3 is a sectional view showing an example of a magnetic card used in the present invention.

FIG. 4 is a waveform chart of a main part for describing the operation of the present invention.

FIG. 5 is a block diagram showing a configuration of a writing unit and a reading unit for explaining an F2F system used in the present invention.

6 is a waveform chart of a main part for describing the operation of FIG.

[Explanation of symbols]

 Reference Signs List 21 input terminal 22 F2F waveform generation circuit 23 head driver 24 magnetic head 25 encryption key generator 26 modulation pulse generator 27 F2F waveform generation circuit 28 head driver 29 magnetic head 31 magnetic head 32 preamplifier 33 F2F demodulation circuit 34 output terminal 35 A / D converter 36 Normalization circuit 37 Modulated / unmodulated wave averaging circuit 38 Authentication circuit 39 Magnetic head 40 Preamplifier 41 F2F demodulation circuit 100 Magnetic card 101 Substrate 102, 103 Recording layer 104 Wear layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/02 G06K 19/00 R (72) Inventor Hirokazu Katagiri 2-2 Shimomeguro, Meguro-ku, Tokyo No. 3 Inside Tamura Electric Works (72) Inventor Mineo Saito 2-3-2 Shimomeguro, Meguro-ku, Tokyo Inside (72) Inventor Atsushi Yoshida 2-2-2 Shimomeguro, Meguro-ku, Tokyo No. 3 F-term in Tamura Electric Works (reference) 5B035 AA13 AA15 BA05 BB02 BB09 BC02 CA38 5B058 CA27 KA13 KA31 YA06 5D031 AA05 BB05 CC01 CC20 EE02 5D091 AA11 BB06 CC30 DD30 HH01 JJ21

Claims (2)

[Claims] 1. A data recording method for a magnetic card using an F2F method in which one value of binary data is recorded at twice the frequency of recording the other value, wherein the magnetic card has a multilayer recording layer. The binary data is recorded on a deep recording layer, and no significant distortion is applied to individual waveforms at the time of recording / reproducing the binary data in accordance with a predetermined pulse arrangement on a surface recording layer. A data recording method for a magnetic card, comprising recording a modulated pulse having a small energy for performing analog modulation. 2. The binary data is recorded on a deep recording layer of a magnetic card by using an F2F system in which recording of one value of binary data is performed at twice the frequency of recording of the other value. In the recording layer, the above-mentioned 2 is applied according to a predetermined pulse arrangement.
A magnetic card authenticity determining method for determining whether or not a magnetic card records a modulated pulse having a small energy to be subjected to analog modulation without giving significant distortion to individual waveforms at the time of recording / reproducing the value data. The data recorded on the deep recording layer of the card is reproduced, and a plurality of modulated waves and unmodulated waves are extracted from the data on the basis of the predetermined pulse arrangement.
D-converting, normalizing, and determining that the magnetic card is normal only when the difference after averaging the plurality of modulated waves and unmodulated waves is within a predetermined value. Authentication method.