JPH0923211A - Device for preventing interception of information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the interception of information included in a leaked radio wave emitted from an electronic apparatus. SOLUTION: This device is provided with a radio wave reception means 53 to receive a leakage electromagnetic wave from an electronic device including information data, a signal detection means 51 to detect the output level of the leakage electromagnetic received by a radio wave reception means, a noise generating means 74 to decide the output level when a noise 55 is outputted based on the output level detected by the signal detection means 51, and a noise transmission means 54 emitting the noise generated by the noise generating means 74 at the decided output level. Since the leakage electromagnetic wave from the electronic device is received and the noise output level is changed accordingly, the S/N is changed and the interception is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiretapping / tapping prevention device for preventing information from being tapped / tapping by unnecessary radio waves leaking from an electronic device.

[0002]

2. Description of the Related Art A phenomenon (radio wave emission) in which an electromagnetic wave (hereinafter referred to as an unnecessary radio wave) which is not intended by a user leaks from an electronic device such as a personal computer (hereinafter referred to as a personal computer) may occur. It is becoming a problem today that information contained in the radio waves may be intercepted / analyzed by a third party to be illegally used. This phenomenon called radio wave emission occurs when a power supply circuit, a communication modem, or the like in a personal computer is operating, or when an information signal passes through a line. The wiring that connects these functions as an antenna that emits unnecessary radio waves, and information leaks out through the power cord. Depending on the surrounding radio environment, if the frequency is 200MHz to 400MHz, which is easy for a PC to output, 70 It is said that there is a possibility that even a position about 80 meters away can be intercepted by using a special receiver.

A method for performing illegal interception will be briefly described with reference to the block diagram of FIG. In the figure, 1 is a computer such as a personal computer, and 9 is a CRT display (CRT: cathode ray tube, which is a display means connected to the computer 1).
Cathode ray tube), 15 are generated when unnecessary electric waves radiated from the CRT display 9, a power supply circuit (not shown) in the computer 1 or a communication modem (not shown), or an information signal passes through the line. Noise, etc., 21 is the unnecessary radio wave 1
A receiving means for receiving 5 and 20 are analyzing means for analyzing the unnecessary radio wave 15 received by the receiving means 21. With such a configuration, the unnecessary radio wave 15 leaking from the CRT display 9 or the like is intercepted by the receiving means 21 installed apart from the computer 1, analyzed by the analyzing means 20, and the unnecessary radio wave is detected. The information contained in 15 is reproduced by a third party and sniffed or eavesdropped.

Therefore, in recent years, a method for preventing the interception of information by intercepting the unnecessary radio wave 15 as described above is being developed. FIG. 15 shows, for example, Japanese Patent Laid-Open No. 6-
It is the figure which showed the conventional method of preventing snooping shown in the publication 214750. In the figure, 1 is a computer and 6 is a computer 1.
, A connector 9 provided on the CRT display, a connector 8 provided on the CRT display 9, a connector 7 connected between the connector 6 and the connector 8, and a computer 1 and a CR.
The cable is a metal cable that is connected to the T display 9. In the cable 7, a plurality of signal lines such as a data signal line 7a and a dummy signal line 7b described later are provided. In addition, in the computer 1, a clock source 2 that oscillates a clock, a display data memory 3 that stores display data, and the display data that is read from the display data memory 3 and is output to a CRT display 9 are generated. A main signal generator 4 and a dummy signal generator 5 for generating a dummy signal are provided. Further, in the CRT display 9, a display circuit 10 for performing control for displaying an image corresponding to this signal transmitted from the computer 1.
And a termination circuit 11 for terminating the dummy signal line 7b.

The operation will be described. In FIG.
The clock oscillated from the clock source 2 in the computer 1 is
The signal is supplied to the signal generator 4 and the dummy signal generator 5.
The signal generator 4 generates a bit-series display data signal synchronized with a clock and sends it to the data signal line 7a. On the other hand, the dummy signal generator 5 generates a dummy signal synchronized with the clock and sends it to the dummy signal line 7b.
On the CRT display 9 side, the display circuit 10 displays an image on the CRT display 9 based on this signal sent from the computer 1 via the data signal line 7a. Further, the dummy signal line 7b that transmits the dummy signal is terminated by the termination circuit 11.

Here, the monochrome CRT display 9
For example, in general, one clock cycle is CR
It corresponds to one dot on the screen of the T display 9.
The main signal output from the main signal generator 4 described above is defined so that the H level represents white and the L level represents black, for example. The change from the L level (black) to the H level (white) and the change from the H level (white) to the L level (black) of this signal are performed in synchronization with the clock oscillated from the clock source 2. The dummy signal also changes in synchronization with the clock, but in this conventional example, it is set so that it changes only at the clock time when the main signal does not change and does not change at the clock time when the main signal changes. That is, this dummy signal is generated at the clock time when this signal is not output.

The unnecessary radio wave 15 leaking from the cable 7 is
Since it corresponds to both the main signal and the dummy signal described above, the original image cannot be displayed even if such an unnecessary radio wave 15 is simply intercepted and displayed on the screen of the display. Can not. As described above, in the conventional method of preventing eavesdropping, the dummy signal line 7b is provided close to the data signal line 7a through which the main signal flows, and the dummy signal is passed through the dummy signal line 7b. I changed it so that it wouldn't be compatible and prevented theft.

[0008]

Since the conventional method of preventing snooping is constructed as described above, the dummy signal generating device 5 is used.
In addition, a clock that does not output this signal is not versatile because it has only versatility to prevent spying on the computer 1 that uses the cable 7 including the dummy signal line 7b. Since it occurs at a time point, in the configuration as shown in FIG. 14 above, the receiving means 21 selectively intercepts the unwanted radio wave 15, or the analyzing means 20 changes the regularity of the main signal and the dummy signal. If you analyze, it will be possible to steal, so
There was a problem that the effect of preventing theft was small. Also,
Since the output level (or the output level ratio) between this signal and the dummy signal is constant and the unnecessary radio wave 15 is not analyzed, the SN ratio (the signal-to-noise ratio) cannot be intentionally changed. There were problems such as.

The present invention has been made to solve the above problems, and sniffs and eavesdrops by intercepting unnecessary radio waves leaking from personal computers and other electronic devices (facsimile, modem, printer). It is possible to prevent eavesdropping and is versatile, and by deliberately changing and degrading the SN ratio necessary for a third party to reproduce information on the electronic device side, it is possible for a third party to snoop and eavesdrop on the information. It is an object of the present invention to obtain a device for preventing wiretapping and wiretapping that can prevent

[0010]

According to a first aspect of the present invention, there is provided a radio wave receiving means for receiving a leaked electromagnetic wave from an electronic device containing information data, and the electromagnetic wave received by the radio wave receiving means. A noise generating means for generating wide-area noise, and an SN ratio when intercepting the electromagnetic wave in order to prevent a third party from intercepting the electromagnetic wave and illegally using the information data. It is an eavesdropping and eavesdropping prevention device that deteriorates.

According to a second aspect of the present invention, the noise generating means generates a noise by the signal detecting section for detecting the output level of the signal by the electromagnetic wave received by the radio wave receiving means, and the noise is detected by the signal detecting section. And a noise radiating section for radiating noise to the outside at the output level determined by the noise generating section. It is an eavesdropping / eavesdropping prevention device.

According to a third aspect of the present invention, the noise generating means outputs the synchronizing signal synchronized with the signal of the information data in the electronic device, and the noise is generated by spreading the information data by the synchronizing signal. The wiretapping / eavesdropping prevention device includes a diffusion pattern generation unit for generating a noise and a noise radiation unit for radiating noise to the outside.

According to a fourth aspect of the present invention, the power supply of the noise generating means is switched on / off by interlocking with switching on / off of the first switch part provided in the electronic device. The second switch section of No. 1 is a wiretapping / tapping prevention device.

According to a fifth aspect of the invention, the first switch section is
This is a device for preventing snooping and wiretapping that is composed of switches for operating keys of electronic devices.

According to a sixth aspect of the invention, the first switch section is
An eavesdropping / eavesdropping prevention device composed of an open / close switch for the lid of an electronic device.

According to a seventh aspect of the present invention, the information data generating section and the display section of the electronic device, which is composed of an information data generating section for generating the information data and a display section for displaying the information data, are connected to each other. A sniffing / eavesdropping prevention device for preventing leaked electromagnetic waves containing information data radiated from a connected section from being intercepted for sniffing / tapping. The scramble means for generating the scramble signal by scrambling the information data and outputting the scramble signal to the connection part and the display part, receiving the scramble signal through the connection part, and receiving the scramble signal This is a device for preventing eavesdropping / eavesdropping which is provided with a descramble means for restoring the original information data.

According to an eighth aspect of the invention, a leaking electromagnetic wave containing the above information data is sniffed from an electronic device including an information data generating section for generating information data and a display section for displaying the information data. An eavesdropping / eavesdropping prevention device for preventing eavesdropping due to eavesdropping, which is provided in the optical cable connecting the information data generating unit and the display unit, and the information data generating unit. An electric / optical converting means for converting the electric signal constituting the optical signal to an optical cable and outputting the optical signal to the optical cable, and the optical signal is received through the optical cable provided in the display unit, and the optical signal is converted into the electric signal. An optical wire / electricity conversion means for preventing the wiretapping / tapping.

[0018]

According to the first aspect of the present invention, the radio wave receiving means for receiving the leaked electromagnetic wave radiated from the electronic equipment and containing the information data in the electronic equipment, and the electromagnetic wave received by the radio wave receiving means. Noise generating means for generating wide area noise, and in order to prevent information data from being illegally used by a third party intercepting the electromagnetic waves, Deteriorate the SN ratio.

According to the second aspect of the present invention, the signal detecting section detects the output level of the received electromagnetic wave, and the noise generating section determines the output level at which the noise generating section outputs noise based on the output level. Make a decision,
By changing the output level of noise according to the output level of the leakage electromagnetic wave and radiating, the signal-to-noise ratio when intercepting the leakage electromagnetic wave is intentionally changed, and the information data contained in the leakage electromagnetic wave is changed. Prevents snooping and wiretapping of information data by making it unreproducible.

According to the third aspect of the present invention, the synchronizing signal output section for outputting the synchronizing signal synchronized with the signal of the information data in the electronic device and the noise by generating the information data by the synchronizing signal are generated. Of the information contained in the leaked electromagnetic wave by degrading the signal-to-noise ratio when intercepting the leaked electromagnetic wave by radiating noise generated by diffusing the information data. Prevents data sniffing and wiretapping of information data.

According to the inventions of claims 4, 5 and 6, a second switch portion which operates in conjunction with the first switch portion provided in the electronic device is provided, whereby the power supply of the noise generating means is provided. Since the on / off of the signal is switched, even when the user does not particularly perform the operation, when the electronic device is used, the noise generating means automatically operates to generate the noise, and the signal pair at the time of intercepting the leaked electromagnetic wave is automatically generated. The noise ratio is deteriorated so that the information data contained in the leaked electromagnetic wave cannot be reproduced, and the information data is prevented from being snooped or tapped.

According to the invention of claim 7, when the information data generated by the information data generator is scrambled and outputted, the original information data is restored when the information data is displayed on the display unit. As a result, the electromagnetic waves leaking from the connection part between the information data generating part and the display part where the electromagnetic waves leak are scrambled, and a third party analyzes them and illegally uses them. I can't.

In the invention of claim 8, since the connection between the information data generating section and the display section is made by the optical cable, electromagnetic waves do not leak, so that a third party illegally uses the information data. Can not do it.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows unnecessary radio waves 1 leaked from an electronic device 70 such as a personal computer, a facsimile, a modem and a printer.
5 is a block diagram showing the structure of a wiretapping / tapping prevention device according to Embodiment 1 of the present invention for preventing wiretapping / tapping by interception of FIG. In FIG. 1, 70 is an electronic device such as a personal computer, a facsimile, a modem and a printer, and 53.
Is a radio wave receiving means having an antenna 53a for receiving the unnecessary radio wave 15 radiated from the electronic device 70, 51 is a signal by the unnecessary radio wave 15 received by the radio wave receiving means 53, and determines the reception level of the signal. Signal detecting means for performing the operation, 52 is noise generating means for changing the output level based on the reception level of the signal determined by the signal detecting means to generate noise, and 54 is noise generated by the noise generating means 52. It is a noise transmitting means composed of a transmitting antenna for transmitting 55.

In the signal detecting means 51, the radio wave receiving means 5
A high frequency detecting section 71 for detecting a signal by the unnecessary radio wave 15 received by 3 and a level detecting section 72 for detecting the reception level of the received signal detected by the high frequency detecting section 71 are provided. Also, the noise generating means 5
2, the transmission level is determined based on the transmission level setting unit 73 to which the reception level detected by the level detection unit 72 is input and set, and the level set in the transmission level setting unit 73, and the output There is provided a noise generator 74 for generating noise 55 at the level.

The electronic device 70 will be described below.
The electronic device 70 includes display data generating means 75 and display means 76 for displaying the display data generated by the display data generating means 75. Electronic equipment 7
When 0 is, for example, a personal computer, as shown in FIG. 2, the display data generating means 75 and the display means 76 are respectively display data generating means 75A which is a personal computer main body.
And a display means 76A which is a display device such as the CRT display 9. Further, when the electronic device 70 is, for example, a facsimile, as shown in FIG.
The display data generating means 75 and the display means 76 respectively include a writing section 7 for writing and reading data.
7 and display unit 78 for displaying data
B, a display unit 76B including a modem 79 for modulating / demodulating a data signal and a binarizing unit 80 for binarizing the data.
It is composed of When the electronic device 70 is, for example, a printer, as shown in FIG. 4, the display data generating unit 75 and the display unit 76 each include a display data generating unit having a writing unit 77 for writing data. 75C and a display unit 76B including a printing unit 81 that prints data.

As described above, in this embodiment,
The radio wave receiving means 53 constitutes a radio wave receiving means for receiving a leaked electromagnetic wave from an electronic device containing information data (display data in this example), and the signal detecting means 5
The noise generating means 52, the noise generating means 52, and the noise transmitting means 54 constitute noise generating means for generating wide-area noise in accordance with the electromagnetic waves received by the radio wave receiving means 53. More specifically, the signal detecting means 51 constitutes a signal detecting portion for detecting the output level of the signal due to the electromagnetic wave received by the radio wave receiving means, and the noise generating means 52 causes the noise. And a noise generating section for determining an output level for radiating the noise based on the output level detected by the signal detecting section. It constitutes a noise radiating section for radiating the noise to the outside at the output level determined by the generating section.

Next, the operation will be described. In the electronic device 70 having the above-described configuration, the display data generated by the display data generating means 75 and displayed by the display means 76 is radiated to the outside as the unnecessary radio wave 15. In the eavesdropping / eavesdrop prevention device of the present invention, first,
The unnecessary radio wave 15 radiated from the electronic device 70 is detected by the radio wave receiving means 53 and input to the signal detecting means 51.
In the signal detecting means 51, the high frequency detecting section 71 detects the received signal, and the level detecting section 72 determines the level of the received signal. The determined level is input to the transmission level setting unit 73 of the noise generation unit 52, and the noise generation unit 7 is based on the level input to the transmission level setting unit 73.
The output level of No. 4 is changed, and the noise 55 at the output level is transmitted from the noise transmitting means 54. At this time, the noise generator 74 generates wideband noise such as white noise. Further, the output level of the noise generating section 74 is based on the reception level of the unnecessary radio wave 15 by the signal detecting means 51, and when the reception level is low, the noise 55 is output at a low level as shown in FIG. Further, when the reception level is high, as shown in FIG. 6, the noise 55 is output at a high level, and the level of the noise 55 with respect to the unnecessary radio wave 15 is changed and output. In any case, as shown in FIG. 5 and FIG. 6, it is desirable that the output level of the noise 55 is always slightly higher than the output level of the unnecessary radio wave 15.

As described above, the eavesdropping / eavesdropping prevention device of the present invention attempts to eavesdrop / eavesdrop on the information contained in the unwanted radio wave 15 by intercepting the unwanted radio wave 15 emitted from the electronic device 70. Noise generating means 52
Since the wide area noise 55 is radiated simultaneously with the unnecessary radio wave 15 by the noise transmitting means 54, the noise 55 is always received when a third party intercepts the unnecessary radio wave 15, and Since the noise 55 has no regularity, it is extremely difficult to remove and analyze the noise 55 from what is received by a third party, and it is almost impossible to reproduce the information included in the unnecessary radio wave 15. Is. Further, in this embodiment, the output level of the unnecessary radio wave 15 is detected by the signal detection means 51, and the output level of the noise generated by the noise generation means 52 is changed based on the detected output level to radiate the noise 55. Since the SN ratio (ratio of the level of the information signal to the noise 55 in the unnecessary radio wave 15) is deteriorated according to the output level of the unnecessary radio wave 15, the third party who intercepts the unnecessary radio wave 15 reproduces the information. Since it is not possible to secure the SN ratio necessary for this, it is difficult to reproduce the information, so that it is possible to prevent the information from being sniffed and tapped. Further, the eavesdropping / eavesdropping prevention apparatus according to the present invention can be used for general electronic devices such as personal computers, facsimiles, modems and printers, and is highly versatile. Further, the radio wave receiving means 53, the signal detecting means 51, and the noise generating means 52 may be built in the electronic device 70 to reduce the size.

Embodiment 2 FIG. In the above-described first embodiment, an example in which the unnecessary radio wave 15 radiated from the electronic device 70 is received and the output level of the noise 55 output from the noise generating means 52 is changed according to the received level has been described. In this embodiment, the synchronization signal of the display data is directly transmitted from the electronic device 70A to the noise generating means 52A.
Noise is generated by using the display data in synchronism with the synchronizing signal, and the noise is output from the noise transmitting means 54 as noise 55. In FIG. 7, 91 is
Reference numeral 92 denotes a sync signal output unit for directly inputting the sync signal of the display data to the noise generating means 52A from the electronic device 70A. Reference numeral 92 denotes an appropriate diffusion pattern based on the display data by the signal synchronized with the sync signal. This is a diffusion pattern generation unit for generating it as noise. Here, as the spreading pattern output from the spreading pattern generating unit 92, for example, broadband noise such as a PN code (pseudo noise code) is used. The other structures are the same as those in the first embodiment, and are therefore denoted by the same reference numerals.

In this embodiment, the sync signal output section 91 constitutes a sync signal output section for outputting a sync signal synchronized with the signal of the information data in the electronic device, and the spread pattern. By the generator 92 spreading the information data by the synchronization signal,
The diffusion pattern generation unit for generating the noise is configured, and the noise transmission unit 54 is configured as the noise emission unit for radiating the noise to the outside.

The operation will be described. The unnecessary radio wave 15 radiated from the electronic device 70A is the same as that in the case of the above-described first embodiment, and thus the description thereof is omitted here. In the electronic device 70A, the synchronization signal output unit 91 generates a synchronization signal of the display data output from the display data generation unit 75, and outputs the synchronization signal to the diffusion pattern generation unit 92 of the noise generation unit 52A. The spreading pattern generation unit 92 generates a spreading pattern signal using display data in synchronization with the input synchronizing signal. Using this spread pattern signal, the noise generator 74 generates the noise 55 corresponding to the noise, and the noise transmitter 54 radiates the noise 55. By radiating the noise 55 in this manner, the unnecessary radio wave 1 can be transmitted as in the first embodiment.
The SN ratio of 5 can be deteriorated, and it is possible to prevent snooping and wiretapping by a third party.

A more detailed description will be given. Here, the above-mentioned display data synchronizing signal means two signals, a vertical synchronizing signal and a horizontal synchronizing signal, as shown in FIG. 8A. In the case of a personal computer, as shown in FIG. 8B, the data signal at the beginning of the display data for one screen of the display screen 83 of the CRT display, that is, the signal corresponding to the display data at the upper left 84 of the screen 83. The latter horizontal synchronizing signal is a data signal at the beginning of each dot row on the screen 83, that is, a signal corresponding to the leftmost display data of each dot row.
That is, the vertical synchronizing signal changes at the timing of each screen, and the horizontal synchronizing signal changes at the timing of each dot row. Similarly, when the electronic device 70 is a facsimile, the vertical synchronizing signal determines the paper position.
The horizontal sync signal determines the beginning of the line. Further, in the case where the electronic device 70 is a printer, the vertical synchronizing signal means a signal used for position determination of the paper (page) in both the laser printer and the dot printer, and the horizontal synchronizing signal means the head of the line. It means the signal used for output. For example, the horizontal synchronizing signal is used as a clock when generating a diffusion pattern, and the vertical synchronizing signal is used as a reset signal for resetting each screen or page.

An example of the method of generating the above diffusion pattern will be described in more detail. For example, as shown in FIG. 9, the synchronization signal output unit 91 includes a horizontal synchronization generation unit 91a for generating a horizontal synchronization signal, a vertical synchronization generation unit 91b for generating a vertical synchronization signal, and a horizontal synchronization signal The clock generator 91c generates N times as many signals (usually N = 1000 or 2000 and frequency is 20 MHz × N times) as a clock signal. FIG.
The horizontal synchronizing signal, the vertical synchronizing signal, and the clock signal are shown in FIG. In addition, the diffusion pattern generation unit 92 is shown in FIG.
As shown in, the shift register 92a, a plurality of exclusive OR circuits 92b and 92c, and a buffer 92d that operates as a rectifier are included. Here, the shift register 92a has a basic function of moving a data signal bit by bit in synchronization with a clock.
C. A signal such as a PN code (pseudo noise code) is generated by performing a predetermined operation in the shift register 92a and the exclusive OR 92c in synchronization with the clock signal generated from the clock generation unit 91c,
The exclusive OR of the display data and the display data is obtained by the exclusive OR circuit 92b and is output to the noise generating unit 74 (see FIG. 7) as a diffusion pattern.

As described above, also in this embodiment, even if a third party sniffs or taps the information contained in the unnecessary radio wave 15 radiated from the electronic device 70A, the SN ratio is deteriorated by the noise 55. Therefore, it becomes impossible to reproduce the information, and it is possible to prevent information snooping and wiretapping, and it is possible to obtain the same effect as that of the first embodiment.

Embodiment 3. In the second embodiment described above,
An example has been described in which the electronic device 70A directly inputs the synchronization signal that is the information of the display data to the noise generating means 52A and outputs the noise corresponding to the signal synchronized with the synchronization signal. However, in this embodiment, Further, as shown in FIG. 11, a power switch section 94 interlocked with the operation key switch 93 of the electronic device 70B is provided in the noise generating means 52 and interlocked with the operation key switch 93 of the electronic device 70B. The noise generating means 52 is operated. Here, as the operation key switch 93 of the electronic device 70B, specifically, when the electronic device 70B is a personal computer, for example, an operation key when a resume function or the like is used and a power supply switch key are used. In the case where the electronic device 70B is a facsimile, a detection switch for detecting the start of output of paper and a detection switch for detecting the start of reading of a transmission original are used. If the electronic device 70B is a printer,
A detection switch or the like for detecting when the paper is output may be used. The other structure is similar to that of the second embodiment, and therefore its description is omitted here.
In this embodiment, the operation key switch 93 constitutes a first switch section provided in the electronic device, and the power switch section 94 is an on / off switch of the first switch section. A second switch unit for switching on / off of the power supply of the noise generating means is configured in conjunction with the switching off.

The operation will be described. The unnecessary radio wave 15 radiated from the electronic device 70B is output from the electronic device 70B by the synchronization signal output unit 91 as in the second embodiment.
The sync signal of the display data is input to the spreading pattern generating unit 92, the display data is spread by the signal synchronized with the sync signal by the spreading pattern generating unit 92, and then input to the noise generating unit 74. At this time, the noise 55 is generated based on this synchronization signal, so that the SN ratio (signal-to-noise ratio) of the unnecessary radio wave 15 including the information of the display data can be deteriorated, and a third party snoops or sniffs. Can be prevented.
Further, in this embodiment, the ON / OFF of the switch 93 of the operation key of the electronic device 70B is turned on / off.
The power switch 9 of the noise generating means 52B is interlocked with the switch.
6 turn on / off automatically at the same time.

As described above, this embodiment has the same effects as those of the first and second embodiments, and further, the switch 9 of the operation key of the electronic device 70B.
Since the operation / non-operation of the noise generating means 52B is switched in association with turning on / off of 3, the noise generating means 52B automatically operates when the electronic device 70B is used, without requiring the user to perform any particular operation. Emits noise 55,
The noise 55 automatically degrades the SN ratio (signal-to-noise ratio) of the unnecessary radio wave 15, and even if a third party intercepts the unnecessary radio wave 15 and tries to reproduce the information contained therein, the information Can not be reproduced, and it is possible to prevent information snooping and wiretapping.

Fourth Embodiment In the third embodiment described above,
As shown in FIG. 11, the noise generating means 52B is operated in conjunction with the operation key switch 93 of the electronic device 70B. However, in this embodiment, instead of the operation key switch 93 of FIG. When the electronic device 70B is a laptop type or notebook type personal computer as the first switch section, the opening / closing switch of the lid is used, and the noise generating means 52B is linked with the opening / closing switch of the lid. To work.

The structure of this embodiment is similar to that of the third embodiment shown in FIG. 11, and therefore will be described below with reference to FIG. The operation will be described. The unnecessary radio wave 15 radiated from the electronic device 70B is the same as in the third embodiment described above.
Based on the display data synchronization signal, the diffusion pattern generator 92
By radiating the noise generated by the noise transmitting means 54, the SN ratio of the unnecessary radio wave 15 (signal-to-noise ratio)
Can be degraded. The operation / non-operation of the noise generating means 52B is switched in association with opening / closing of the lid of the electronic device 70B.

As described above, also in this embodiment, the noise generating means 5 is interlocked with the on / off switch of the lid of the electronic device 70B without any special operation by the user.
Since 2B is made to operate, the SN ratio (signal-to-noise ratio) of the unnecessary radio wave 15 can be automatically deteriorated while the information device 70B is being used. Even if a third party tries to reproduce the information, the information cannot be reproduced, and it is possible to prevent the third party from snooping or wiretapping the information. In addition, in the present embodiment, the electronic device 7
Since the noise 55 is generated by the open / close switch of the 0B lid, especially in the case of a laptop computer,
When the CRT display 9 and the computer main body 1 are integrated, the lid 55 can be opened and closed to generate the noise 55 only when it is used, which requires no user operation and Sometimes it is possible to prevent eavesdropping and wiretapping.

Embodiment 5 FIG. In the above-described first to fourth embodiments, the example in which the noise 55 is generated to deteriorate the SN ratio (noise-to-signal ratio) regarding the unnecessary radio wave 55 has been described, but in this embodiment, it is shown in FIG. As described above, when the display data generating means 75 ′ outputs the display data, the data is scrambled, that is, encrypted and then output on the signal line 7c, and the display means 76 ′ returns to the original display data. By displaying it,
The unnecessary radio wave 15 is leaked from the cable 7A connecting the display data generating means 75 'and the display means 76' and is scrambled even when a third party intercepts the leaked radio wave 15. Disable the reproduction of the information contained in.

The configuration will be described. In FIG.
70C is an electronic device such as a personal computer, and 75 '
Is a display data generating means composed of a main body such as a personal computer, and 76 'is a display means such as a CRT display. A clock source 2 for oscillating a clock, a display data memory 3 for storing the display data, a display data memory 3 for reading the display data from the display data memory 3, and scrambling it in the display data generating means 75 '. Scrambler 95 which is a scramble means
Are provided. Further, in the display means 76 ', a descramble section which is a descramble means for returning the scrambled display data received from the scramble section 95 via the signal line 7c in the cable 7A to the original display data. 96, and a display circuit 10 for displaying the display data restored by the descrambling unit 96.
Are provided.

Next, the operation will be described. The display data stored in the display data memory 3 is scrambled by the scrambler 9
5, the display data is scrambled to generate a scrambled signal. This scrambled signal is input to the descramble section 96 in the display means 75 ′ via the connector 6, the cable 7A and the connector 8, where the scramble is released to obtain the original display data, and the display circuit 10 sends it. Is displayed.

As described above, in this embodiment, since the cable 7A connecting the display data generating means 75 'and the display means 76' is composed of a metal cable or the like, this cable 7A is an aerial wire. And the display data is radiated from there as unnecessary radio wave 15. Therefore,
Since the display data is diffused by scrambling the display data itself transmitted via the cable 7A, even if a third party intercepts the unnecessary radio wave 15,
The information contained in the unnecessary radio wave 15 cannot be reproduced, and it is possible to prevent information snooping and wiretapping. In addition,
In this embodiment, the scrambled dummy signal may be sent together with the display data, and the descramble unit 96 may remove the dummy signal.

Embodiment 6 FIG. In the above described fifth embodiment,
The cable 7A is a metal cable, but in this embodiment, the optical cable 101 is used instead. The configuration will be described. In FIG. 13, 70D is an electronic device, 75 ″ is a display data generating means, and 76 ″ is a display means. Reference numeral 103 denotes an electric / optical conversion unit which is provided in the display data generating means 75 ″, reads the display data from the display data memory 3, and converts it from an electric signal into an optical signal (optical conversion). Yes, 100 is an optical connector provided in the display data generating means 75 ″, 102 is an optical connector provided in the display means 76 ″, 101 is an optical cable connected between the optical connector 100 and the optical connector 102. , 104 is
The electric / optical conversion unit 103 is provided in the display means 76 ″.
An optical / electrical conversion unit for converting an optical signal received from the optical cable 101 via the optical cable 101 into an electric signal.

Next, the operation will be described. Electronic device 70
At D, on the side of the display data generating means 75 ″, the electric / optical conversion unit 103 reads the display data stored in the display data memory 3, performs optical conversion of the display data, and converts it into an optical signal. Next, the optical signal is transmitted to the display means 76 ″ via the optical cable 101, the optical signal is converted into an electric signal by the optical / electrical conversion unit 104 on the display means 76 ″ side, and further displayed. When the means 76 '' is a CRT display, it is converted into a CRT display display signal (R, G, B, horizontal, vertical) as required and displayed on the screen. In this embodiment,
Since the optical cable 101 is used as the connection cable, the unnecessary radio wave 15 (see FIG. 12) does not leak.

As described above, in the present embodiment, in the electronic device 70D, for example, the connection cable for connecting the display data generating means 75 "and the display means 76" is changed from the conventional metal cable to the optical cable 101. By doing so, the emission of the unnecessary radio wave 15 is eliminated, and even if a third party sniffs or sniffs the information of the display data, the information cannot be reproduced and the sniffing or sniffing of the information can be prevented.

[0049]

According to the first aspect of the invention, the electric wave receiving means for receiving the leaked electromagnetic wave radiated from the electronic device and containing the information data in the electronic device, and the electric wave receiving means for receiving the electromagnetic wave. Noise generating means for generating wide-area noise according to electromagnetic waves, and intercepting the electromagnetic waves in order to prevent information data from being illegally used by a third party intercepting the electromagnetic waves. Since the SN ratio at the time of doing so is deteriorated, there is an effect that it is possible to prevent snooping and wiretapping of information data. Further, it can be applied to all electronic devices, and versatility can be improved.

According to the second aspect of the present invention, the signal detecting section detects the output level of the received electromagnetic wave, and the noise generating section outputs the noise level based on the output level of the noise generating section. So that
By changing the output level of noise according to the output level of the leakage electromagnetic wave and radiating, the signal-to-noise ratio when intercepting the leakage electromagnetic wave is intentionally changed, and the information data contained in the leakage electromagnetic wave is changed. I tried not to reproduce it, so
The effect that it is possible to prevent snooping and wiretapping of information data by a third party is exerted.

According to the third aspect of the present invention, a noise is generated by the synchronizing signal output section for outputting the synchronizing signal synchronized with the signal of the information data in the electronic device and by spreading the information data by the synchronizing signal. And a diffusion pattern generating unit for radiating noise generated by diffusing the information data, thereby deteriorating the signal-to-noise ratio when intercepting the leaked electromagnetic wave and being included in the leaked electromagnetic wave. Since the information data is prevented from being reproduced and the information data is prevented from being sniffed or sniffed, it is possible to prevent the third party from sniffing or sniffing the information data.

According to the fourth, fifth and sixth aspects of the present invention, the second switch section which operates in conjunction with the first switch section provided in the electronic device is provided, whereby the noise generating means is provided. Since the power is turned on / off, the noise generation means automatically operates to generate noise when the electronic device is used, and the signal when intercepting a leaked electromagnetic wave is used even if the user does not perform any operation. Since the noise-to-noise ratio is deteriorated so that the information data included in the leaked electromagnetic waves cannot be reproduced, there is an effect that it is possible to prevent a third party from snooping or tapping the information data.

According to the seventh aspect of the present invention, when the information data generated in the information data generating section is scrambled and outputted, the original information data is reproduced when the information data is displayed in the display section. Since the electromagnetic wave leaks from the connection part between the information data generating part and the display part where the electromagnetic wave leaks is scrambled, a third party analyzes it and illegally uses it. Since it is not possible to do so, there is an effect that it is possible to prevent a third party from sniffing or wiretapping the information data.

According to the invention of claim 8, since the connection between the information data generating section and the display section is made by the optical cable, the electromagnetic wave does not leak, so that a third party illegally copies the information data. Since I made it impossible to use it,
The effect that it is possible to prevent snooping and wiretapping of information data by a third party is exerted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wiretapping / tapping prevention apparatus according to a first embodiment of the present invention for preventing wiretapping / tapping by interception of unnecessary radio waves leaking from an electronic device.

FIG. 2 is a block diagram showing an example of an electronic device (personal computer).

FIG. 3 is a block diagram showing an example (facsimile) of an electronic device.

FIG. 4 is a block diagram showing an example (printer) of an electronic device.

FIG. 5 is a diagram showing a relationship between levels of unnecessary radio waves and noise emitted from the wiretapping / tapping prevention device of the present invention when the reception level of the unnecessary radio waves is low.

FIG. 6 is a diagram showing a relationship between levels of unnecessary radio waves and noise radiated from the wiretapping / tapping prevention device of the present invention when the reception level of the unnecessary radio waves is high.

FIG. 7 is a block diagram showing a configuration of a wiretapping / eavesdropping prevention device including an electronic device according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a vertical synchronizing signal and a horizontal synchronizing signal in the second embodiment.

FIG. 9 is a partial block diagram showing a detailed configuration of the second embodiment.

10 is a diagram showing a vertical synchronizing signal, a horizontal synchronizing signal, and a clock signal in FIG.

FIG. 11 is a block diagram showing a configuration of a wiretapping / eavesdropping prevention device including an electronic device according to a third embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration of a wiretapping / tapping prevention device according to a fifth embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a wiretapping / tapping device according to a sixth embodiment of the present invention.

FIG. 14 is a block diagram showing a conventional method of illegally intercepting unnecessary radio waves.

FIG. 15 is a block diagram showing a conventional anti-theft system.

[Explanation of symbols]

1 computer, 2 clock sources, 3 display data memory,
4 signal generators, 5 dummy signal generators, 7 cables, 9 CRT displays, 10 display circuits, 11
Termination circuit, 15 unnecessary radio waves, 20 analyzing means, 21 receiving means, 51 signal detecting means, 52 noise generating means, 53
Radio wave receiving means, 54 noise transmitting means, 55 noise, 7
1 high frequency detector, 72 level detector, 73 transmission level setting unit, 74 noise generator, 75 display data generator, 76 display unit, 77 write unit, 78 reader, 79 modem, 91 sync signal output unit, 92 spreader Pattern generating section, 93 operation key switch, 94 power switch section, 95 scramble section, 96 descramble section, 100, 102 optical connector, 101 optical cable, 103 electric / optical converting section, 104 optical / electric converting section.

Claims (8)

[Claims] 1. A radio wave receiving means for receiving a leaked electromagnetic wave from an electronic device containing information data, and noise for generating a wide area noise according to the electromagnetic wave received by the radio wave receiving means. A snooping characterized by deteriorating an SN ratio when intercepting the electromagnetic wave in order to prevent a third party from intercepting the electromagnetic wave and illegally using the information data. -An eavesdropping prevention device. 2. The noise generating means, a signal detecting portion for detecting an output level of a signal by the electromagnetic wave received by the radio wave receiving means, the noise generating means, and the noise detecting means for detecting the output level of the signal. A noise generator for determining an output level for radiating the noise based on the output level, and a noise emitter for radiating the noise to the outside at the output level determined by the noise generator. The wiretapping / eavesdropping prevention apparatus according to claim 1, wherein 3. The synchronizing signal output section for outputting a synchronizing signal synchronized with the signal of the information data in the electronic device, and the noise generating means for spreading the information data by the synchronizing signal, The eavesdropping / eavesdropping prevention device according to claim 1, further comprising: a diffusion pattern generation unit for generating noise, and a noise emission unit for radiating the noise to the outside. 4. A first switch section provided in the electronic device, and a first switch section for switching on / off of the power supply of the noise generating means in association with turning on / off of the first switch section. The eavesdropping / eavesdropping prevention apparatus according to claim 1, further comprising a second switch section. 5. The eavesdropping / eavesdropping prevention device according to claim 4, wherein the first switch section is composed of a switch of an operation key of the electronic device. 6. The eavesdropping / eavesdropping prevention device according to claim 4, wherein the first switch portion is configured by an opening / closing switch of a lid of the electronic device. 7. An electronic device comprising an information data generating section for generating information data and a display section for displaying the information data, wherein the information data generating section and the display section are connected to each other. A sniffing / eavesdropping prevention device for preventing leaked electromagnetic waves containing the above information data radiated from a connecting part, which is intercepted for sniffing / tapping, and is provided in the above information data generating part. Scrambling means for scrambling the information data to generate a scrambled signal and outputting the scrambled signal to the connection section, and the display section, which receives the scrambled signal via the connection section. And a descrambling means for returning the scrambled signal to the original information data. 8. An electronic device including an information data generating unit for generating information data and a display unit for displaying the information data causes leakage electromagnetic waves containing the information data for sniffing and eavesdropping. A device for preventing eavesdropping / eavesdropping for preventing interception, the optical cable connecting the information data generating unit and the display unit, and the information data generating unit, An electric / optical conversion means for converting the electric signal constituting the optical signal into an optical signal and outputting the optical signal to the optical cable, and the optical signal which is provided in the display unit and receives the optical signal via the optical cable. An eavesdropping / eavesdropping prevention device comprising: an optical / electrical conversion unit for converting into an electric signal.