RU2290766C1 - Method for protecting technical means from information loss across primary electric power grid and device for realization of method - Google Patents

Abstract

FIELD: confidential communications, possible use for protecting technical means for processing information, in secondary power source of which compensating voltage stabilizer is used, from loss of information via primary electric power grid and via channels of collateral electromagnetic radiations and inductions.

SUBSTANCE: in the method, voltage of primary electric power grid is rectified, filtered, modulated by noise signal, after that subjected to compensation stabilization with impulse adjustment and is used for powering the load. Device for realization of method (dwg.2) contains, serially connected: primary electric power grid 1, rectifier 2, filter 3, voltage modulator 4, compensating voltage stabilizer 6 and load 7. To second input of voltage modulator 4 the output of generator of noise signal 5 is connected.

EFFECT: decreased power of noise signal used for concealing information loss signals.

2 cl, 3 dwg

Description

The invention relates to techniques for confidential communication and can be used to protect technical means, the secondary power source of which contains a compensation voltage stabilizer, from information leakage through the primary power supply network and through the channels of spurious electromagnetic radiation and interference (PEMIN).

Power supply of information processing equipment (TSOI) is carried out from built-in or external sources of secondary power supply (IWEP). The secondary power source, as a rule, is a system for automatically controlling the voltage on the output buses of the source, and therefore the law of change in the energy taken by the IWEP from the primary power supply is strictly correlated with the law of the change in the power consumed by the TSOI from the IWEP.

An analysis of the spectrum of incident electromagnetic waves generated in the power supply network and in the PEMIN leakage channels by operating IEPs, which are part of the information processing equipment, shows that the current consumption changes simultaneously with the processed information and a spectrum of incident electromagnetic waves forms, which propagates through the wires of the primary power supply network and through PEMIN leakage channels, by receiving and analyzing which it is possible to recover information processed in the TSOI. To protect confidential information from unauthorized removal through the wires of the power supply network and through the PEMIN channels, technical means and methods of protection are used that prevent the interception of information through leakage channels.

A means of protection against information leakage on the wires of the power network is a network electrical protection filter [1]. The disadvantage of the filtering method is that the protection filters must have a sufficiently large attenuation for side signals, which can be achieved only with a significant increase in the weight and size characteristics of the IWEP and TSOI. In addition, the electric filter does not provide suppression of spurious electromagnetic radiation from IVEP.

Another way of protecting against electromagnetic radiation from side electromagnetic oscillations is the protective shielding of IVEP and TSOI [2], [3]. The disadvantage of the method of shielding is the presence of local violations of the electrical leakage of the screen in the installation of covers, hatches and indicators. In these places, electromagnetic waves go beyond the screen and can be intercepted by electronic intelligence. To ensure a high degree of electrical leakage of the screen, design complexity and an increase in the weight and size characteristics of IVEP and TSOI are required. In addition, metal screens of technical equipment are subject to mandatory grounding, which is not always feasible at the place of operation of the TSOI.

There is a method of protection against electronic intelligence, by which the power supply stabilizer is connected to the power circuits of the TSOI nodes processing confidential information [4].

The disadvantage of this method is its complexity, which leads to the complication and appreciation of TSOI. The situation is aggravated by the fact that the stabilizer of the consumed current [4] automatically ensures the constancy of the consumed current of the TSOI, at the level of the maximum peak value of the consumed current when processing information signals, which leads to an increase in energy consumption and requires the use of a more powerful IVEP to power the TSOI.

There is a method of actively countering radio intelligence, which generate electromagnetic noise and direct them towards the likely location of the radio intelligence [5], [6].

The known method has several disadvantages.

The continuous emission of noise masking signals with a power exceeding the power of the side signals worsens the electromagnetic environment at the location of the TSOI and creates obstacles to the normal functioning of both the protected and other technical means.

In addition, noise electromagnetic radiation worsen the environmental situation at the location of the TSOI.

There is a method of protecting information received via wired communication channels, and a system for its implementation, based on noise in the speech frequency range of the wire line by connecting a noise generator to it [7]. The known method and device provide noise of the communication line through which information signals of low power are transmitted and are unsuitable for noise of the power line, for example 220 V.

Known methods of protecting information processed by a PC and LAN from leakage through the power supply network, based on the use of generators for masking information noise signals in phase circuits and the neutral of the power supply system [8, p.70]. The use of a noise generator allows you to create a level of a masking signal of the order of 40-60 dB, which is considered sufficient for reliable protection of this channel of information leakage [8, p. 71]. The disadvantage of network noise generators is the large radiated power, which worsens the environmental and electromagnetic environment around the protected technical means.

The closest in purpose and technical essence to the proposed technical solution and therefore selected as a prototype is a method of protecting a technical device from information leakage on the primary power supply network, according to which the primary power supply network is noisy using a noise signal generator that is turned on at the connection point of the technical means to the primary power supply network. At the same time, in the primary network there is a vector addition of the noise signal with information signals penetrating the power supply network [9].

Figure 1 presents an example of a device that implements the known method (product NG-201 [9]).

The device is connected to the primary power supply network 1 and contains a switching device 2, TSOI 3, the generator 4 noise signal.

The output of the primary power supply network 1, for example, an alternating current source of voltage 220 V, 50 Hz, is connected through a switching device 2 to the input of the TSOI 3. The output of the noise generator 4 is connected to the second input of the switching device 2. Switching device 2 is designed to connect the noise generator 4 and TSOI 3 to the primary power supply network and is a conventional power outlet in products of type NG-201.

Figure 1 also presents an example implementation of TSOI 3, used later in the description of the proposed method and device.

TSOI 3 contains series-connected IVEP 3.1 and the load, for example, a portable PC 3.2. IVEP 3.1 contains series-connected rectifier 3.1.1, filter 3.1.2 and compensation voltage stabilizer 3.1.3. The input of the rectifier 3.1.1 is the input of the IVEP 3.1 and the input of the TSOI 3, the output of the compensation voltage stabilizer 3.1.3 is the output of the IVEP 3.1.

The rectifier 3.1.1 of the alternating voltage of the primary network 1 generates a constant voltage containing ripple (frequency harmonics 50 Hz). These ripples are smoothed out by a filter 3.1.2, at the output of which a primary constant voltage is generated, which in the compensation voltage stabilizer 3.1.3 is converted to the required value with simultaneous voltage stabilization, resulting in a secondary constant voltage used to power the load 3.2.

Masking of information leakage signals appearing in the primary power supply network due to changes in the load current is carried out by additively superimposing (summing) the input network resistance of the primary network of information leakage signals and noise signals generated by the generator 4.

The disadvantage of this method and device that implements it, is as follows.

Firstly, high-quality noise requires a significant power of the noise signal, commensurate with the power consumed by the technical means. For example, for the network noise generators described in [9], it is from 2 to 10 watts. The need to provide high power noise signal complicates the design of the generator 4 noise signal and increases the cost of its manufacture.

Secondly, since the wires of the primary power supply network are an antenna, a part of the power of the noise signal is emitted into the surrounding space, which worsens the environmental situation at the location of the technical equipment, as well as the electromagnetic environment, as it interferes with electronic equipment.

Thirdly, the noise signal, penetrating the protected TSOI along the power supply circuit, makes it necessary to filter this signal in the TSOI to prevent a decrease in noise immunity of signal processing, which further complicates the technical tool and increases the cost of its manufacture. It should also be noted that the fact of the use of a high-power noise signal in the TSI is easily detected by radio intelligence, which unmasks the object on which such tools are used, indicating the confidentiality of information processing in the object. In addition, the main purpose of network noise generators is to protect against technical means of tacit information retrieval installed in eavesdropping rooms. These tools transmit information over the power network in the high frequency range, of the order of 50 ÷ 500 kHz. Network noise generators generate interference in the same frequency range. However, information leakage signals caused by a change in the power consumed from the IVEP, and consequently, the power from the AC network, occupy the frequency band from 100 Hz to f _sq / 2 Hz, where f _sq is the pulse repetition rate in the voltage stabilizer converter [15, p. 141-142]. The selection of power from the power supply network takes place during the time measured by units of milliseconds [10, p.17, Fig. 4] at the moments of maximum voltage in the power supply network. At these moments, fragments of information messages penetrate the power network. Known noise generators do not provide the formation of noise signals of the required power (about 10 W) in a wide range from 100 Hz to 50 kHz and therefore cannot prevent information leakage caused by uneven load current.

The situation is aggravated by the fact that when using pulse-width modulation (PWM) or pulse-frequency modulation (PFM) methods in voltage converters in the case of constant power consumption, the pulse width of the converter remains constant and pulse sequences are formed in the leakage channels (front and rear harmonics) fronts) with a constant shift in time. When changing the current taken by the technical means from the IVEP, the invariance of the time shift between the pulses in the leakage channel is violated and thus information about the law of change in the consumed current appears in it.

The objective of the proposed method and device for its implementation is to protect the technical means from information leakage on the primary power supply network while fulfilling the requirements for environmental and electromagnetic safety.

The technical result achieved by the method and device is to reduce the power of the noise signal.

The essence of the proposed technical solution lies in the operation of modulating the rectified voltage of the rectified voltage of the primary power supply network at the input (on the power buses) of the compensation voltage regulator with a noise signal.

The modulation operation is carried out using a voltage modulator connected between the output of the filter and the input of the compensation voltage stabilizer, the second input of which is connected to the output of the noise signal generator.

The modulation of the voltage on the power buses of the compensation voltage stabilizer according to a random law leads to a random change in the current consumed by the stabilizer due to the use of the stabilizer to compensate for any changes due to negative feedback: when the supply voltage decreases, the current consumption increases, and when the supply voltage increases, the current consumption decreases. It is known that stabilizers must maintain a constant voltage at the output, even if the input voltage fluctuates significantly, for example, for the stabilizer μA 7805 [10, p.23] the output voltage will change no more than 4.65 V to 5.35 V when the input voltage fluctuates from 8 to 20 V. Therefore, a change in the voltage at the input of the stabilizer in the above range under the influence of the voltage of the noise generator will mask the changes in the power consumed by the stabilizer due to changes in the load current consumed Go technical means while maintaining the specified requirements for the output voltage. In addition, connecting the noise generator to the input of the voltage modulator allows you to decouple from the 220 V network and switch to a lower power noise generator, which greatly simplifies the design of the device as a whole.

Moreover, if pulse regulation methods (PWM or PFM) are used in the compensation stabilizer, the parameters of these pulses will randomly change in accordance with the voltage at the stabilizer input, which creates a continuous noise spectrum of spurious emissions that mask information leakage through the PEMIN channels.

Achieving the claimed technical result, which is to provide protection against information leakage using low-noise noise signals (compared to the prototype), is based on the use of the operation of modulating the voltage supply voltage of the compensation stabilizer with a noise signal. As is known, modulating (multiplicative) interferences have higher masking properties than additive ones used in the prototype [11, pp. 8-9]. This kind of interference is characteristic of fading communication channels. A comparative assessment of the effect of additive and multiplicative noise (fading) on the reliability of the communication channel, at a fading rate commensurate with the signal duration, is given in [12]. If the dispersion of the signal and noise in the communication channel is equal, that is, with the signal-to-noise ratio β = 1 (0 dB), it follows from the graph given in [12, p. 152, Fig. 5.6] that, with additive noise, the reliability of the channel communication is E _b = 4 · 10 ^-1 , and in the presence of fading E _b = 2 · 10 ^-3 . The given values of E _b show that in channels with multiplicative noise at a signal-to-noise ratio β = 1, the probability of correct transmission of an information unit is 200 times less than in channels with additive interference at a similar signal-to-noise ratio.

Figure 1 presents the functional diagram of the device of the prototype,

figure 2 - of the inventive device that implements the proposed method,

figure 3 is an example implementation of a voltage modulator.

The claimed device (figure 2) contains the following blocks:

1 - primary power supply network;

2 - rectifier;

3 - filter;

4 - voltage modulator;

5 - noise generator;

6 - compensation voltage stabilizer;

7 - load.

The output of the primary power supply network 1 through a series-connected rectifier 2, filter 3, voltage modulator 4, compensation stabilizer 6 is connected to the input of the load 7. The output of the noise generator 5 is connected to the second input of the voltage modulator 4.

Compensation voltage stabilizer 6 contains the following blocks:

6.1 - voltage reference source,

6.2 - driver imbalance signal,

6.3 - adjustable converter

6.4 - rectifier,

6.5 - filter.

The output of the reference voltage source 6.1 through the imaging device 6.2 mismatch is connected to the first input of the adjustable transducer 6.3, the second input of which is the input of the compensating voltage regulator 6, and the output through a series-connected rectifier 6.4 and the filter 6.5 is connected to the second input of the imaging mismatch 6.2. The output of the filter 6.5 is the output of the compensation voltage regulator.

An example of the implementation of a compensation voltage regulator with pulse regulation on the K 142EP1 chip is given in [13, p.128, Fig.5.4], a description of the operation of which in the PWM mode is given in [13, p.129] and therefore is not described here.

An example of the implementation of rectifier 2, filter 3, voltage modulator 4 is taken from [14, p. 219, Fig. 10.11 and 10.12], which provides a detailed description of the operation and calculation of blocks. Some difference is introduced into the circuit of the voltage modulator 4, namely, that the reference voltage source is made on the divider R _C and R _D [Fig.3].

The noise signal generator 5 can be performed, for example, according to the circuit shown in [15], in which instead of the WA antenna it is necessary to connect the input of voltage modulator 4 via a capacitor C 2 (Fig. 3).

Modulator 4 contains an input divider made on resistors R _C and R _D , an output divider made on resistors R _A and R _B , a through stage 4.1 and a feedback amplifier (OS) 4.2. The input divider from the constant voltage generated by the rectifier 2 generates a reference voltage U _op supplied to the first input of the amplifier OS 4.2, the second input of which receives a voltage U _X generated by the output divider from the output voltage U ₀ .

The device that implements the proposed method is as follows.

The alternating voltage of the primary power supply network 1, for example 220 V, 50 Hz, is converted by the rectifier 2 to a constant. The ripple of this voltage (frequency harmonics of 50 Hz) is smoothed out by a filter 3. The ripple-smoothed voltage is the primary constant supply voltage of the feed-through stage 4.1 and of the OS 4.2 amplifier and is also used to generate voltage U _op .

When exposed to a noise signal generated by the noise generator 5, the voltage at the first input of the OS 4.2 amplifier will contain a random component. The OS amplifier isolates the difference signal between the voltages at the amplifier inputs and outputs it to the 4.1 stage cascade, which changes its conductivity in such a way as to equalize the voltages at the first and second inputs of the OS 4.2 amplifier, while the output voltage U ₀ supplied to the power bus of the compensation stabilizer voltage 6 will also contain a random multiplicative component due to the modulation effect of voltage U _{op by a} noise signal. This component will mask the information leakage signals appearing on the power buses of the compensation stabilizer due to load changes. The amplitude of the random component, on the one hand, should be no less than the amplitude of the information leakage signal, since only in this case the masking properties of the multiplicative noise will appear, as was mentioned earlier, as well as in [12, p. 152], and on the other hand, it must be within the limits not exceeding the allowable change in the supply voltage of the compensating voltage stabilizer, which the latter can compensate (stabilize).

Compensation voltage stabilizer 6 stabilizes the input voltage (if it is within the specified limits) and at its output produces an already stabilized secondary DC voltage supplied to the load 7. As shown by the practice of the TSOI developments, it is advisable to use compensation stabilizers with pulse regulation using PWM methods in which, when the input voltage changes, the pulse duration changes. If the input voltage contains a random component, then the pulse duration will also change according to a random law, as a result of which the spectrum of spurious emissions from deterministic turns into continuous, by which it is impossible to determine the law of information change.

The operation of a compensation stabilizer with pulse regulation is described in detail in [13, p.128-130] and therefore is not given here.

Thus, the first factor affecting the degree of masking of side signals is a random change in the current taken from the power supply due to the noise of its multiplicative (modulating) noise with a power comparable to the leakage current power. At the same time, the limits of changes in the current taken from the power supply network during the protection of the IEDs should be commensurate with the limits of the changes in the current taken from the power supply network during the processing of information and when the protection of the IEDs from information leakage is disabled.

The second factor determining the degree of masking of side electromagnetic oscillations is that the voltage on the supply buses of the compensation voltage stabilizer 6 changes randomly when the voltage modulator is operating, which leads to random changes in the pulse width of the PWM and, accordingly, to the destruction of the information component contained in envelope of side signals.

It should also be noted that since the generator 5 of the noise signal is not galvanically connected to the wires of the power supply network and the compensation voltage regulator, there is no transmission of energy of this generator to the power supply network and to the surrounding area, which does not allow the intruder to use compensation reception methods, and, in addition provides randomness of side signal changes without increasing the energy of these signals, which in turn improves the electromagnetic and environmental conditions at the location of the technical FIR means.

The above confirms the attainability of the technical result, which consists in reducing the power of the masking signal while observing the requirements for electromagnetic compatibility and environmental requirements.

Information sources

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Claims (2)

1. The method of protecting the technical means from information leakage on the primary power supply network, based on the use of the operations of generating a noise signal, converting the voltage of the primary power supply network to primary DC voltage, generating a secondary constant voltage using a compensation voltage stabilizer, characterized in that the operation of forming a secondary constant voltage is carried out after modulation of the primary DC voltage by a noise signal. 2. A device for protecting a technical device from information leakage on the primary power supply network, comprising a noise signal generator, a rectifier, a filter, a compensating voltage stabilizer, a load, while the output of the primary power supply through a rectifier is connected to the filter input, the output of the compensating voltage stabilizer is connected to the load, characterized in that a voltage modulator is introduced into it, the first input of which is connected to the output of the filter, the second to the output of the noise generator, and the output to the input compensation voltage stabilizer.

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