An information leakage protection apparatus and method for a power line

Abstract

The present application belongs to the field of electromagnetic information security, and relates to a device and method for protecting information leakage of power lines, characterized in that: at least comprising a noise source for generating wideband noise, a noise source, a power line coupling circuit and a power line, the noise source for generating wideband noise is coupled with the power line through the noise source and the power line coupling circuit, and transmits wideband noise to the power line to absorb information leakage caused by the power line. The device provided by the present application has low cost and high efficiency, and can effectively complete the protection of electromagnetic information leakage of power lines, which is of great significance to electromagnetic information security.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic information security and relates to a device and method for protecting power lines from information leakage. Background Technology

[0002] With the rapid development of computer technology, single computer devices have evolved into broader computer systems (computers, computer peripherals, network devices, etc.). As these broader computer systems operate on wider frequency bands, have larger information transmission capacities, and are used more extensively, electromagnetic information security issues have arisen. Research has shown that the electromagnetic conduction and radiation generated by these systems during operation carry a great deal of operational information, which can be intercepted and even recovered under certain conditions, leading to information leakage and compromising information security.

[0003] Traditional electromagnetic information leakage protection mainly targets shielding of space radiation fields and using jammers to generate external radiation noise interference. These technologies can protect against electromagnetic information leakage caused by space radiation fields within a certain range. However, they are insufficient for electromagnetic information leakage caused by conduction. Generally, only low-frequency filtering protection is applied to power lines in the 150k~30MHz band.

[0004] In recent years, information leakage caused by power lines at high frequencies has gradually attracted the attention of researchers. Numerous engineering tests have proven that power lines can be used as transmission lines to transmit useful electromagnetic signals over a certain distance, causing information leakage. With the advancement of power line carrier technology, broadband power line communication technology using OFDM modulation can now transmit large-capacity communication signals over a certain distance in a frequency band ranging from tens of MHz to hundreds of MHz. Since the signals transmitted by generalized computer systems are digital pulse trains, their spectral characteristics are very similar to those of power line carrier signals. Therefore, generalized computer systems face a high-frequency, broadband information leakage threat, posing a significant security risk.

[0005] For power line protection, the conventional method is to use passive electromagnetic leakage protection power filters to filter the coupling signals generated by generalized computer systems on the power line. However, research shows that because generalized computer systems couple very strongly to high-frequency signals from power lines, and many power strips installed in classified office spaces with electromagnetic leakage protection power filters cannot achieve proper grounding and can only be grounded through a grounding wire, which is usually very long, the grounding impedance increases exponentially when transmitting high-frequency signals. This causes the electromagnetic leakage protection power filter to lose its suppression effect on high-frequency signals, resulting in a vulnerability in power line protection. Summary of the Invention

[0006] The purpose of this invention is to provide a simple, easy-to-use information leakage protection device and method for power lines that prevents electromagnetic information leakage.

[0007] The objective of this invention is achieved as follows: an information leakage protection device for power lines, characterized in that it includes at least a noise source that generates broadband noise, a noise source, a power line coupling circuit, and a power line. The noise source that generates broadband noise is coupled to the power line through the noise source and the power line coupling circuit to transmit broadband noise to the power line in order to absorb information leakage caused by the power line.

[0008] The noise source that generates broadband noise includes a PN junction semiconductor device, a noise amplifier circuit, and a circuit that causes the PN junction to reverse break down. The circuit that causes the PN junction to reverse break down is loaded onto the PN junction semiconductor device, causing the PN junction semiconductor device to generate broadband noise. The noise amplifier circuit receives the amplified broadband noise signal and couples it to the power line through the noise source and power line coupling circuit to transmit the broadband noise to the power line in order to absorb the information leakage caused by the power line.

[0009] The noise amplification circuit includes at least two stages, and after injection, the noise signal level on the power line is stabilized between 55dBμV and 75dBμV.

[0010] The broadband noise coverage frequency range is 30MHz to 400MHz.

[0011] It further includes: power supplies for noise sources that generate broadband noise, circuits that cause reverse breakdown of PN junctions, noise amplification circuits, and power line coupling circuits.

[0012] The power supply for the noise source that generates broadband noise, the circuit that causes the PN junction to break down in reverse, the noise amplification circuit, and the power line coupling circuit is further connected to the power line. The power line provides AC power, which is then supplied to the DC voltage source of the above circuits via an AC / DC conversion circuit.

[0013] The noise source that generates broadband noise, the circuit that causes the PN junction to break down in reverse, the noise amplification circuit, the power line coupling circuit, and the DC voltage source are all fixed inside the housing.

[0014] The housing is a power distribution box, and the DC voltage source input AC power terminal inside the power distribution box is the power line terminal of the power distribution box.

[0015] It also includes a power supply abnormality alarm circuit, which is optically connected to a DC voltage source through an optocoupler to monitor whether there is an abnormality in the power supply of the noise injection module. If there is a power supply abnormality, an audible and visual alarm will be triggered. If the power is cut off, the working indicator light will turn off.

[0016] A method for protecting against information leakage over power lines, characterized by: at least a noise source generating broadband noise, a noise source, a power line coupling circuit, and a power line; the noise source generating broadband noise is coupled to the power line through the noise source and the power line coupling circuit; the noise source generating broadband noise includes a PN junction semiconductor device, a noise amplification circuit, and a circuit that causes reverse breakdown of the PN junction; the circuit that causes reverse breakdown of the PN junction is applied to the PN junction semiconductor device, causing the PN junction semiconductor device to generate broadband noise; the PN junction semiconductor device uses diode D3 as the noise source, and 12V is adjusted by a sliding rheostat R3 to make it operate in a reverse critical conduction state; the generated noise signal is coupled into the subsequent circuit through C4; three resistors R9, R12, and R13 form an impedance transformation unit, transforming the impedance value of the circuit to 50Ω, enabling the subsequent circuit to work normally; the noise signal enters the first-stage amplifier after passing through C5, and the first-stage amplifier operates at 30MHz. The noise signal is stably amplified within a frequency range of 400MHz. Resistor R4 is responsible for voltage division, ensuring the amplifier operates at a suitable voltage point. L1 blocks high-frequency noise from the power supply from affecting the amplifier. Similarly, the noise signal is amplified by the second and third stage amplifier circuits. Finally, the signal is coupled through capacitor C8 and output to the impedance transformation unit composed of R8, R10, and R11. After transforming the line impedance to a suitable value, it is injected into the power line through coupling capacitors C9 and C10, resulting in stable white noise interference on the power line.

[0017] The advantages of this invention are: it uses a combination of a passive electromagnetic leakage protection module and an active broadband noise interference module to protect against electromagnetic information leakage from power lines. The final form is a power socket, with all modules concentrated inside the socket. Users can use the device like a regular socket. It can not only effectively filter out electromagnetic interference signals in the power network, but also prevent generalized computer systems from transmitting useful electromagnetic information to the power grid through power lines, thus providing effective protection for information security in confidential locations. Attached Figure Description

[0018] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings: Figure 1 This is a circuit block diagram (schematic diagram of active broadband interference noise module) of an embodiment of the present invention.

[0019] Figure 2 This is a circuit diagram of an active broadband interference noise module according to an embodiment of the present invention;

[0020] Figure 3 This is a test diagram of the effect of an active broadband interference noise module.

[0021] In the diagram, 1 is the noise source that generates broadband noise; 2 is the power line coupling circuit; 3 is the power line; 4 is the PN junction semiconductor device; 5 is the noise amplification circuit; 6 is the circuit that causes the PN junction to reverse break down; 7 is the power supply; 8 is the housing; and 9 is the power supply abnormality alarm circuit. Detailed Implementation

[0022] like Figure 1 As shown, an information leakage protection device for power lines includes at least a noise source 1 that generates broadband noise, a noise source, a power line coupling circuit 2, and a power line 3. The noise source 1 that generates broadband noise is coupled to the power line 3 through the power line coupling circuit 2 to transmit broadband noise to the power line 3 in order to absorb information leakage generated on the power line 3.

[0023] To achieve the generation and stabilization of broadband interference noise, a noise amplification circuit 5 is included. This circuit amplifies the generated original noise signal, stabilizing the interference noise from noise source 1 and ensuring that the noise signal level on the power line is stabilized between 55dBμV and 75dBμV after injection. The broadband noise coverage frequency range is 30MHz to 400MHz.

[0024] To power the entire circuit, an AC / DC switching power supply 7 is used to convert the input 220V AC power into 12V DC power for the entire circuit.

[0025] The active broadband interference noise circuit for power lines also includes a power supply abnormality alarm circuit 9, which monitors whether there is an abnormality in the power supply of the noise injection module through optocouplers. If there is a power supply abnormality, an audible and visual alarm will be triggered. If the power is cut off, the working indicator light will turn off.

[0026] like Figure 2 As shown, a specific circuit of an embodiment of the present invention is given. The power supply 7 used in the entire circuit is 12V. The noise source 1 that generates broadband noise includes a PN junction semiconductor device 4, a noise amplification circuit 5, and a circuit 6 that causes the PN junction to reverse break down. The PN junction semiconductor device 4 uses a diode D3 as a noise source. The 12V is adjusted by a sliding rheostat R3 to make the voltage applied to D3 work in the reverse critical conduction state.

[0027] The generated noise signal is coupled into the subsequent circuit through C4. The three resistors R9, R12, and R13 form an impedance transformation unit, which transforms the impedance value of the circuit to 50Ω, enabling the subsequent circuit to work normally.

[0028] After passing through C5, the noise signal enters the first-stage amplifier, which stably amplifies the noise signal within a frequency range of 30MHz to 400MHz. Resistor R4 is responsible for voltage division, ensuring the amplifier operates at a suitable voltage point, while L1 blocks high-frequency noise from the power supply from affecting the amplifier. Similarly, the noise signal is amplified by the second and third-stage amplifier circuits. Finally, the signal is coupled through capacitor C8 and output to the impedance transformation unit composed of R8, R10, and R11. After transforming the line impedance to a suitable value, the signal is injected into the power line through coupling capacitors C9 and C10, resulting in stable white noise interference on the power line.

[0029] After the active broadband interference noise injection module was built, it was powered on and tested. A spectrum analyzer and current clamps were used to measure the noise level on the power line. The final measured noise level on the power line was as follows: Figure 3 As shown, based on the magnitude of electromagnetic information leakage in a generalized computer system, the level of injected noise needs to be between 55dBμV and 75dBμV, covering the original signal in the frequency range of 30MHz to 400MHz, so that the electromagnetic information leakage signal cannot be detected on the power line, thus achieving effective protection against electromagnetic information leakage.

[0030] The noise source 1 that generates broadband noise, the circuit that causes reverse breakdown of the PN junction, the noise amplification circuit, the power line coupling circuit, and the DC voltage source are all fixed inside the housing 8. The housing is a power distribution box, and the AC input terminal of the DC voltage source inside the power distribution box is the power line terminal of the power distribution box.

[0031] Diode D3 is a Zener diode. Zener diodes have the characteristic of generating a lot of noise at the critical value of reverse conduction. A noise generation circuit is built using the diode, and the voltage applied to the diode is adjusted so that the diode outputs a wide-bandgap flat noise signal.

[0032] The noise amplifier circuit 5 adopts a three-stage amplifier circuit: a three-stage amplifier is used to stabilize the noise signal, so that the noise level is stable and meets the injection quantity requirements.

[0033] Power line coupling circuit 2 uses a capacitor to couple and inject the amplified noise signal generated by the diode onto power line 3, ensuring a stable noise signal on power line 3. The use of capacitor coupling takes reliability into consideration. To prevent short circuits in the capacitor and direct entry of the high voltage from power line 3 into the circuit, a safety capacitor with an open-circuit failure mode must be used for coupling and injection.

[0034] The power supply abnormality alarm circuit 9 is responsible for monitoring the operation of the entire circuit and whether there is any abnormality in the power supply. If an abnormality in the power supply of the AC / DC switching power supply is detected, an audible and visual alarm will be triggered.

[0035] The housing of this invention is in the form of a power socket, with all circuits concentrated inside the socket. Users can use the device just like using a conventional socket. It can not only effectively filter out electromagnetic interference signals in the power network, but also prevent generalized computer systems from transmitting useful electromagnetic information into the power grid through power lines, thus providing effective protection for information security in confidential locations.

Claims

1. A device for protecting against information leakage from power lines, comprising a noise source (1) that generates broadband noise, a power line coupling circuit (2), and a power line (3), wherein the noise source (1) is coupled to the power line (3) through the power line coupling circuit (2), characterized in that: The noise source (1) includes a PN junction semiconductor device (4), a noise amplification circuit (5), and a bias circuit (6) that causes the PN junction to reverse break down. The bias circuit (6) includes a sliding rheostat (R3) for precisely adjusting the reverse bias voltage across the PN junction semiconductor device (4) so ​​that it operates in the critical state of reverse breakdown. The noise source (1) also includes a first impedance transformation unit composed of three resistors (R9, R12, R13) to precisely transform the output impedance of the noise signal to 50Ω. The noise amplification circuit (5) includes a three-stage amplifier, wherein the first stage amplifier includes a resistor (R4) and an inductor (L1). The resistor (R4) is used to provide a suitable voltage division, and the inductor (L1) is used to block high-frequency noise in the power supply to ensure stable amplification of the noise signal in the frequency range of 30MHz-400MHz. The power line coupling circuit (2) includes a capacitor coupling circuit composed of capacitors (C9, C10). The capacitors (C9, C10) are safety capacitors used to safely inject the amplified noise signal into the power line (3).

2. A device for information leakage protection of power lines according to claim 1, characterized in that: The PN junction semiconductor device (4) is a Zener diode (D3), whose reverse breakdown voltage is precisely adjusted to the critical conduction state by a sliding rheostat (R3).

3. The information leakage protection device for power lines according to claim 1, characterized by: The three-stage amplifier amplifies the noise signal to a level range of 55dBμV~75dBμV.

4. The information leakage protection device for power lines according to claim 1, characterized by: The broadband noise coverage frequency range is 30MHz~400MHz.

5. The information leakage protection device for power lines of claim 1, wherein: It also includes a power supply (7), which is electrically connected to the power line (3) and converts the 220V AC power provided by the power line into a 12V DC voltage source through an AC / DC conversion circuit.

6. The information leakage protection device for power lines according to claim 1, characterized in that: It also includes a power supply abnormality alarm circuit (9), which is connected to a DC voltage source through an optocoupler to monitor the power supply status in real time. When a power supply abnormality is detected, it triggers an audible and visual alarm and turns off the working indicator light when the power is cut off.

7. The information leakage protection device for power lines according to claim 1, characterized in that: All circuit components of the device are fixed inside the housing (8), which is a power distribution box structure, and its power input terminal is directly connected to the power line (3).

8. A method for information leakage protection of power lines, using a protection device according to any one of claims 1 to 7, characterized in that Includes the following steps: The reverse bias voltage applied to the two ends of the PN junction semiconductor device (4) is precisely adjusted by the sliding rheostat (R3) to make it work in the reverse breakdown critical state and generate a broadband noise signal; the output impedance of the generated noise signal is precisely transformed to 50Ω by the impedance transformation unit composed of three resistors (R9, R12, R13); the noise signal is amplified step by step by a three-stage amplifier circuit, in which the first stage amplifier stably amplifies the noise signal in the frequency range of 30MHz-400MHz; the amplified noise signal is injected into the power line (3) by the coupling circuit composed of safety capacitors (C9, C10); the noise signal level injected into the power line (3) is controlled to be stable between 55dBμV-75dBμV, effectively covering the original information leakage signal.

9. The method of claim 8, wherein: The PN junction semiconductor device (4) uses a Zener diode (D3), and the sliding rheostat (R3) is adjusted to make it work in the reverse breakdown critical state.

10. The method of claim 8, wherein: It also includes real-time monitoring of the device's power supply status through a power supply abnormality alarm circuit (9), and automatically triggering an audible and visual alarm when a power supply abnormality is detected.

Images