RU18036U1 - SECRET COMMUNICATION SYSTEM - Google Patents

Description

Secret Communication System.

The utility model relates to communication technology and can be used to organize the secret transmission of speech, data and documentary information over a public telephone network.

Known confidential communication devices 1, 2, 3J, containing a telephone installation, switching elements, a speech-converting device (RPU), an encoder, a decoder, a signal conversion device, providing a connection between subscribers of a public telephone network (PSTN) and conducting secret telephone conversations. The disadvantage of these devices is their limited functionality, since they provide for the secretion of only one type of information - speech.

A 4J duplex communication system transceiver is known that provides the transmission of two types of information: data and documentary information via a pre-connected classified communication channel while protecting the transmitted information from channel interference and from imposing false information by the adversary.

The disadvantage of this device is its low functionality, since voice transmission is not provided, and a dedicated secret communication channel is also required.

Closest to the proposed technical solution and chosen as a prototype is a confidential communication system 5, which ensures the transmission and classification of speech, data and documentary information on PSTN, as well as protecting data and documentary information from channel interference and from imposing false information by the adversary.

The known communication system comprises a telephone installation, a first switching unit, connected in series with two-way communications. RPU. a second switching unit, a cryptographic unit, a third switching unit and a matching unit connected to a communication channel with the exchange. The system also includes a power supply, a closed-circuit sensor and a transceiver, made according to certificate No. 10965 4, containing a mode input unit, data terminal equipment, a nmith protection unit and a data reliability increasing unit.

When the telephone set (telephone set) of the telephone set (MGT) is picked up, power is supplied to all units of the system, which is set in a state in which it is possible to establish a connection using the PSTN method and maintain both open and classified ones (by pressing a button in the closed mode sensor ) telephone conversations.

If it is necessary to transfer data and documentary information, subscribers agree on this by telephone, and then set the required mode by the switching elements of the data transceiver mode input block 4. In this case, a data transceiver is connected to the cryptographic block instead of the RPU and it becomes possible to transmit information as described in 5. Upon completion of data transfer and documentary information, subscribers can switch to telephone mode by pressing the corresponding buttons in the data transceiver, at the same time, the data path is disconnected and the voice path is connected. At the end of telephone conversations, subscribers put MTT, as a result of which the power turns off and the system returns to its original state.

A feature of the well-known classified communication system is the location of the cryptographic unit n RPU in close proximity to the source of information and thereby the implementation of subscriber classification, providing the greatest security of information transfer. Such inclusion of a cryptographic unit and RPU is advisable in case of a large traffic of information to be classified.

In conditions of low traffic, the use of a cryptographic block, which is the most expensive element of the system, becomes inefficient, since this block will be idle most of the time. Given the need to manufacture, distribute a large amount of key information, service the cryptographic unit with specialized personnel in a separate room, and repair it, a secret communication system built using subscriber security, when each subscriber is equipped with a cryptographic unit, becomes unreliable.,

The objective of the proposed technical solution is to increase the reliability of the secret communication system.

The technical result achieved by the proposed classified communication system is to use a cryptographic unit to classify group paths, which is achieved by including it not in the subscriber field, as in the prototype, but in the channel field of the telephone exchange (PBX), so the cryptographic block will be effectively used in mass service mode of a number of subscribers. Because

the required number of sets of cryptographic blocks is equal to the number of communication channels between the exchanges. which is much smaller than the number of subscribers, the communication system is much simpler and more reliable.

In addition, due to the possibility of placing all sets of cryptographic blocks in one room, the costs of operating the system are reduced (repair, security, manufacturing and distribution of key information ...).

The features of the proposed technical solution, common with the features of the prototype, are: a telephone, a data transceiver, an automatic telephone exchange, a speech-converting device, a first, second and third switching unit and a cryptographic unit, while the input and output of the telephone are connected respectively to the first output - input the first switching unit, the second input and output of which are connected respectively to the output and input of the data transceiver, the signal input and output of the secret communication system ineny respectively to the control input and output of the automatic telephone exchange. The first information and clock outputs of the speech-converting device are connected respectively to the first and second inputs of the third switching unit, the first output of which is connected to the first information input of the cryptographic unit, connected by the second information output and input, respectively, to the information output and input of the secret communication system.

Signs of the proposed technical solution that differ from the prototype are a discrete information transceiver and a signal analysis unit, while the first and second control inputs of the secret communication system are connected respectively to the first and second control inputs of the first switching unit, the third output and input of which are connected respectively to the first input and the output of an automatic telephone exchange. The second input of the automatic telephone exchange is connected to the output of the second switching unit, the second output to the first input of the transceiver of discrete information and the information input of the RPU. The second information output of the RPU is connected to the first input of the second switching unit, and the second information and first clock inputs, respectively, to the third information and first clock outputs of the cryptographic block, the second clock and third information output of which are connected respectively to the second and third inputs of the transceiver of discrete information. The fourth input of the latter is connected to the second output of the third switching unit, the first and second outputs, respectively, with the second input of the second switching unit and the fourth input of the third switching unit, the third output is with the third input of the third unit

switching and the first input of the signal analysis block, the fourth output with the first clock input of the cryptographic block and the fifth input of the signal analysis block, and the fifth with the second clock input of the cryptographic block and the second input of the signal analysis block. The first and second outputs of the signal analysis unit are connected respectively to the control inputs of the second and third switching units, and the third and fourth inputs are respectively connected to the control output of the automatic telephone exchange and the signal input of the secret communication system.

The essence of the proposed technical solution lies in the inclusion of RPU and cryptographic unit in the channel field of an automatic telephone exchange, thereby reducing the total number of equipment used. At the same time, to ensure the transmission of data and documentary information through the data transceiver located at the subscriber, the RPU is switched off according to the commands allocated by the signal analysis unit, which is also included in the channel field of the automatic telephone exchange.

On fng.1 presents a functional diagram of the proposed technical solution,

figure 2, 3, respectively, of the second, third switching units,

figure 4 - output device

in Fig.5 - input device.

in FIG. 6 - signal analysis unit.

in FIG. 7 - matching device

in FIG. 8 - node alarm

in FIG. 9 - analyzers of occupation and hang up.

in FIG. 10 - blocks allocation teams.

The proposed secret communication system contains the following nodes:

1 - telephone set

2. 3, 4 - respectively, the first, second and third switching units,

5- automatic telephone exchange,

6 - speech-transforming device,

7- cryptographic block,

8 - transceiver of discrete information,

9- signal analysis unit,

The proposed system has the following connections (Fig. 1).

The input and output of the telephone set 1 are connected respectively to the first output and input of the first 2 switching unit, the second input and output of which are connected respectively to the output and input of the data transceiver 10. The first and second control inputs of the first 2 switching unit are connected respectively to the first 11 and second 12 the control inputs of the secret communication system, and the third output and input, respectively, with the first input and output of the automatic telephone exchange 5. The second input of the automatic telephone exchange 5 is connected to the output the second 3 switching units, and the second output - to the first input of the transceiver of discrete information 8 and the information input of the speech-converting device b, the first information and clock output of which are connected respectively to the first and second inputs of the third 4 switching unit. The second information output of the speech-converting device 6 is connected to the first input of the second 3 switching units, and the second information and first clock inputs, respectively, to the third information and first clock outputs of the cryptographic unit.

The second clock and third information outputs of the cryptographic unit 7 are connected respectively to the second and third inputs of the discrete information transceiver 8, the fourth input of which is connected to the second output of the third 4 switching units, the first and second outputs, respectively, with the second input of the second 3 switching units and the fourth input of the third 4 switching units, the third output - with the third input of the third 4 switching units and the first input of signal analysis unit 9, the fourth output - with the first clock input of the cryptographic unit 7 and the fifth input of the signal analysis unit 9. and the fifth output with the second clock input of the cryptographic unit 7 and the second input of the signal analysis unit 9.

The first and second outputs of the signal analysis unit 9 are connected respectively to the control inputs of the second 3 and third 4 switching units.

Information input 13 and output 14 of the secret communication system are connected respectively to the second input and output of the cryptographic unit 7.

The control output of the automatic telephone exchange 5 is connected to the third input of the signal analysis unit 9 and the signal output 15 of the secret communication system, the signal input 16 of which is connected to the fourth input of the signal analysis unit 9 and the control input of the automatic telephone exchange 5.

N fl

Telephone set 1 is intended for the day of establishing a connection and conducting telephone conversations on PSTN. As a telephone set, for example, a TA-68M 6 telephone set can be used.

The first 2 switching unit is designed to connect either the telephone set 1 or the data transceiver 10 to the automatic telephone exchange 5, depending on the control signals received at the control inputs of the first 2 switching unit, and can be performed, for example, in the form of a switch or a button when exposed to the operator

The second 3 switching unit is designed for switching to the input of an automatic telephone exchange 5, either signals from the output of the RPU 6, or signals from the output of the transceiver of discrete information 8. depending on the presence of a signal at its control input. The second 3 switching unit (figure 2) contains a key implemented on the transistor VI, in the collector circuit of which is included the relay coil K1. When a signal is received at the control input, the key is opened and relay K1 is activated, for example, type RES-80, the contacts of which switch the corresponding circuits.

The third switching unit 4 (FIG. 3) is intended for switching to the input of the cryptographic unit 7 either signals from the input of the RPU 6 or signals from the output of the transceiver of discrete information 8, depending on the presence of a signal at its control input and contains two switches. The first 41 switch commutes the clock frequency, the second 42 information signals according to the signal received at the control input of the third 4 switching unit (inverter 43 input).

ATS 5 is designed to establish a connection route between PSTN telephone subscribers. As automatic telephone exchanges, stations of a ten-step or coordinate system 7 produced by industry can be used.

As known. 7. Fig. 7.1, 7.2 p. 156-166 such stations include relay sets of connecting lines having information circuits used for transmitting and receiving information (in Fig. 1 these are the second input and output of ATS 5) and signal circuits, used for transmitting and receiving interaction signals and the called number (in Fig. 1, this is the first and second control outputs).

RPU b is designed to convert an analog speech signal to a discrete one using a transmitting RPU 62 and an inverse transform when receiving using a receiving 61 RPU and can be implemented, for example, by author. testimonial. USSR YOU 088061 MKL G10L J / 06.

the encoder 74 and the modulator 75 in the path, and the decoder 71 in the receive path, the automatic frequency control unit 72 and the demodulator 73. Examples of the implementation of the AFT system are a demodulator for a special case of two-interval codes, for example, bi-pulse at the C1-FL joint (GOST 27232-87) are given 8. The encoder 74 and the decoder 71 are similar to those used in the prototype 5.

When receiving voice information, the information and clock frequency FT are issued respectively for the third and first outputs, and when receiving data, for the third and second (2 FT for bi-pulse signal) outputs of the cryptographic block

The transceiver of discrete information 8 is designed to receive information from the telephone exchange and transmit it to the side of the telephone exchange and contains in the receiving path (Fig. 1) an input device 81, a demodulator 82, an AFC unit 83. and in the transmitter, an output device 84 and a modulator 85.

Input 81 and output 84 devices are designed for matching the electrical parameters of the signals transmitted through information circuits between the PBX 5 and the transceiver 8. Demodulator 82, modulator 85 and block АПТЧ 83 can be performed similarly to the corresponding nodes of cryptographic block 7 (if the modulation and demodulation methods are equal, used on the side of the communication channel and on the side of the exchange). At the same time, the information and clock frequency necessary for classifying information are issued on the third and fifth outputs, and the clock frequency (2 FT for bi-pulse coding) for the modulator 75 is on the fourth output of the discrete information transceiver 8.

The output device 84 (Fig. 4) contains operational amplifiers D1 (microcircuit 1401CA1) and D2 (microcircuit 544UD2A), a Zener diode VI (type 2C147A), resistances that specify the operating mode (R1-R6 for the amplifier Dl, R7-R9 for the amplifier D2).

The input device 81 (Fig. 5) contains a transformer T, a comparator D1 (chip 521 SAZ 9), designed to form the fronts of incoming signals, a Zener diode VI (type 2C147A), a transistor V2 (type 2T316 9), a Schmidt trigger D2 (chip 564TL1 9 ), elements R1-R6. C, setting the mode of operation of the comparator and R7.R8 - transistor V2).

The signal analysis unit 9 is designed to isolate the interaction signals between the telephone exchanges when establishing a connection between telephone subscribers, highlighting the data transmitted by the transceiver for disconnecting and connecting the RPU, and generating control signals for this connection and disconnection.

the first 91 and second 92 matching devices,

signaling unit 93,

first 94 and second 95 occupation analyzers,

first 96 and second 97 hang up analyzers,

generator 98,

unit for selecting Data Transfer and Phone 99 commands.

trigger 910. elements OR 911 and 912.

The data transfer and Phone 99 command isolation block contains:

the first 991 and second 992 combination analyzers,

first 993 and second 994 counters,

trigger 995.

Matching devices 91 and 92 (Fig. 7) are designed to match the electrical parameters of the signals transmitted; on signal circuits between the PBX 5 and the signal analysis unit 9. The matching device contains a diode bridge V1-V4, switch K1. optocoupler pair V5 (ZOT110B) integrating the R4 chain. C, Schmidt trigger D1, resistances Rl, R2, R3 and R5, specifying the operation mode of the optocoupler pair V5. Switch K1 is designed to establish the appropriate polarity of the signal received from the telephone exchange.

The V5 optocoupler is designed for galvanic isolation of ATC circuits and the proposed device

The signaling unit 93 (Fig. 8) is designed to signal the reception of a signal. Occupation and is implemented on the transistor V2, the collector circuit of which includes LED VI.

Occupation analyzers 94 and 95 are designed to isolate the Occupation signal (a pulse of 40-60 ms duration) received at the third and fourth inputs of the signal analysis unit 9. When the Occupation signal is detected, trigger 910 is triggered through the OR 911 element, the output signal of which triggers the alarm unit 93.

The hang up analyzers 96 and 97 are designed to isolate the End signal (a signal with a duration of 600-1000 nsec), which arrives at the third or fourth inputs of the signal analysis unit 9. When the End signal is detected, the end analyzer 96 (97) via the OR 912 element resets trigger 910, as a result which turns off the LED in the alarm unit 93.

The combination analyzers 991 and 992 are designed to highlight the combinations Data transfer on the Phone (for example, combinations F09A. 46B1 in the hexadecimal system).

Combination counters 993 and 994 are designed to count the number of combinations in a specific time interval. The signal from the counter 993 triggers the trigger 995, reset by the signal from the output of the counter 994.

Figure 9 presents the electrical circuit diagrams of the analyzers of occupation 94 (95) and rebound 96 (97) (implementation example).

The occupation analyzer contains a shift register 941, triggers 942-944, a counter 945, AND elements 947 - 9412. Inverters 9413, 9414, OR elements 9415 - 9421.

The inverter 9413 and the And 948 element select the leading edge of the signal entering the occupation analyzer, the inverter 9414 and the And 949 element the trailing edge. In the initial state, the trigger 910 (Fig.6) is in a position in which the signal And 947 (fng. 9) opens with a signal from the inverse output, while at the input D of the trigger 942 there is a signal that, when a leading edge is allocated, passes to the output of the trigger 942 , which through the element And 9411 is attached to the frequency fl. and through the AND 9412 element, it starts the counter 945, which, after counting 40 pulses, gives a signal that sets the trigger 943 to state 1, the output of which trigger 944 is prepared for the arrival of the trailing edge of the Occupation or End call signal. If the trailing edge is allocated in the range from 40 to 60 ms, then a signal appears at the output of trigger 944, setting the trigger 910 (Fig. 6) to a position in which a signal appears at the direct output of trigger 910, which is then sent to the signaling unit. If the trailing edge is highlighted after 60 ms. then the counter 945 through the elements OR 9418. 9420 (Fig.9) is reset trigger 943. which means that the incoming signal is not a signal Occupation.

The hang-up analyzer contains a counter 961, triggers 962-964, AND elements 965. 966, OR elements 967-9610 n and works as follows. The leading edge of the signal arriving at the analysis unit, from the output of the And 948 element, the trigger 964 is set to state 1 and if the polarity of the input signal has not changed, a signal will appear at the output of the And 966 element, which opens the And 965 element while the pulses of frequency fl arrive at the clock the input of the counter 961, which counts the duration of 600 ms and gives a signal to set the trigger 962 to state 1. If the signal received at the input of the analysis unit is the End signal, i.e. its duration is 600 - 1000 ms. then at the time of the trailing edge of this signal from the output of the AND 949 element, the trigger 963 is set to state 1, and the signal from its output through the OR element 912 (Fig.6) trigger 910 is set to O. If the signal duration is more than 1000

ms then the counter 961 (fng. 9) works, setting the triggers 962-964. 910 to state O.

The data transceiver 10 is designed to receive and transmit data and documentary information while providing protection against the imposition of false information and can be performed on a test basis. No. 10965 4.

In FIG. 10 is a schematic electrical diagram of the data transfer and Phone 99 command isolation block. The first command is allocated by the F09A combination analyzer 991, built on register 9911, AND elements 9912 to 9914. OR element 9915, counter 993, counting eighteen sixteen-bit combinations in a row (element 9932), and a counter (element 9931) forming a time interval equal to the length of one combination. The second command is allocated by the analyzer 992 combination 46B1. built on the register 9921, AND elements 9922. 9923 and OR element 9924 and counter 9941 (elements 9941, 9942).

The secret communication system according to the functional diagram of FIG. 1 works as follows.

In the initial state (before the connection was established), sets of channel-forming equipment and the cryptographic unit that are working against each other over the communication channel are in synchronism at the set speed for this communication channel. Establishing a connection for telephone calls is as follows. When the telephone receiver is picked up by the subscriber-initiator of communication (hereinafter referred to as subscriber A), the loop of the subscriber line of the ATS of the site of the initiator of communication (US-1) is closed, the ATS, if it is possible to service the subscriber line, sends a continuous harmonic signal with a frequency of 425 Hz to the handset (Ready signal) . In response, subscriber A dials the PBX number of the incoming communication node (US-2). After dialing the first digit of the PBX number, the US-1 stops issuing the Ready signal. After dialing the last digit of the number, the PBX US-1 determines the direction corresponding to the PBX US-2, connects the telephone circuits of the telephone set of subscriber A to its information channel circuits and transmits the Occupation signal (pulse duration 40-60 ms) through the control output. the system output arriving at channel 15 to the channel-forming equipment and to the third input of the signal analysis unit 9. In the signal analysis unit US-1, the signaling unit 93 and the Occupation signal work through the channel-forming equipment US-1. the communication channel enters into and from the channeling equipment US-2 to the signal input of the classified communication system and to the fourth input of the signal analysis unit 9, as well as to the control input of the automatic telephone exchange US-2. At the same time, in the signal analysis unit 9, the signaling unit 93 also operates.

iu 8UOQ01SIAi54

US-2 in cm-tea of the possibility of servicing this channel gives the second output to the subscriber information (microphone) circuit a continuous harmonic signal with a frequency of 425 Hz (Ready signal), which is fed to the first input of the RPU and converted into a discrete (binary) form in it. Binary signal Readiness is issued on the first information output in RPU 6 accompanied by the FT clock frequency. issued by the first clock output of the RPU 6. and through the third switching unit 4 it is supplied respectively to the first information input and the second clock input of the cryptographic block 7. The Ready signal is classified in the encoder 74, modulated in the modulator 75 in accordance with the adopted modulation method, for example, converted to BI signal, for which the 2Рг frequency is used, which is fed to the first input of the cryptographic block. Secret signal. Readiness for the second information output of the cryptographic block is sent to the informer. Mutation output 14 of the secret communication system to the channel-forming equipment US-1. The signal Readiness received through the communication channel after reverse conversion in cryptographic unit 7 and RPU 6 US-1 through the PBX US-1 through the subscriber (telephone) circuits enters the MTT of subscriber A. who, having heard the Ready signal from the PBX US-2, to which the TA is connected the called subscriber (subscriber B), dials the telephone number of subscriber B. In this case, the numbers from the control output of the PBX US-1 are issued to the channel-forming equipment US-1, which transmits them over the communication channel. The numbers of the subscriber’s number B received from the communication channel, the channel-forming equipment US-2 issues to the signal input 16, from which they enter the ATS-2. The last one after receiving the first digit of the number removes the Ready signal, and after the last digit arrives, it generates and issues the Call signal (intermittent signal with a frequency of 25 Hz) to the telephone set of subscriber B, and the signal to send calls (CPV) for information from subscriber (microphone) circuits ( intermittent harmonic signal 425 Hz) for transmission through the communication channel towards the calling subscriber A. The path of the CPV signal to the MTT of subscriber A is similar to the path of the Ready signal from the PBX US-2.

After the MGT is removed, subscriber B closes the loop of the subscriber line. PBX US-2 detects this fact and removes the Call and CPV signals. connects its information circuits (through RPU 6 and cryptographic unit 7) to the telephone set of subscriber B, and outputs to the signal output 15 of the secret communication system a signal The response of the subscriber, which enters the channel-forming equipment US-2, for transmission through the communication channel to the channel-forming equipment US-1. Signal received on the communication channel Subscriber's response channel-forming equipment US-1 by signal

input 16 gives the PBX US-1. which, by this signal, carries out the connection of its information channel circuits to the microphone circuits of the telephone apparatus of subscriber A. Then it becomes possible to conduct duplex classified telephone conversations between subscribers A and B.

After the negotiations are over, one of the subscribers, for example, B, puts MTT on the telephone first, and the loop of the subscriber line is opened towards the PBX US-2. Having detected a loop open, the PBX US-2 generates a Busy signal (intermittent harmonic signal 425 Hz) through the subscriber information (microphone) circuits through the RPU 6 and the cryptographic unit 7, which goes along the same path as the telephone information and goes to the MTT of subscriber A .. Subscriber A, upon hearing the Busy signal, puts the MTT on the telephone, while the loop of the subscriber line opens towards the PBX US-1. which, upon detecting an open circuit, destroys a previously established connection, generates and issues a control signal on the control output. The signal arriving in the signal analysis unit and channel-forming equipment US-2, through which the signaling unit is turned off in the signal analysis unit 9, and the channel-forming equipment transmits the signal through the communication channel to channel-forming equipment US-2. The last one on the control output gives the End signal to the signal analysis unit 9 US-2 and the automatic telephone exchange US-2, while in the signal analysis unit 9 the signaling unit is also turned off and the previously established connection is destroyed.

The transfer of data and documentary information is carried out as in the prototype. At the beginning, as described above, a telephone connection is established. Subscribers in secret telephone mode agree on a data transfer mode, after which the first switching unit disconnects the telephone 1 from the PBX 5 and connects the data transceiver 10 to the PBX by supplying a control signal to the first 11 control input of the device, and set this mode by switching elements of the data transceiver 10 4. At the same time, the latter issues the Data Transfer command, which through the first 2 switching unit, ATS 5, and the discrete information transceiver 8 enters the signal analysis unit 9. The analysis unit for signals 9 it selects this command and for the first and second outputs it gives signals that set the second 3 and third 4 switching units to a state in which RPU 6 is disconnected from the information path, while the second information input and output of the exchange 5 through the second 3 switching unit , discrete information transceiver 8, third 4 switching unit, cryptographic unit 7 are connected to information output 14 and input 13 of the secret communication system. At the same time, the FT clock frequency necessary for secreting information is issued at the fifth output of the transceiver

discrete information 8 and goes to the second input of the cryptographic input 7 to the encoder 74. The clock frequency is 2Pt. necessary for the operation of the modulator 75, is issued on the fourth output of the transceiver of discrete information and is fed to the first clock input of the cryptographic unit 7.

When receiving data and documentary information, the information is fed to the information input 13 of the classified communication system, demodulated in the demodulator 73. it is declassified in the decoder 71 and accompanied by the clock frequency (2Рг for the BI signal generated by the AHTCH 72 unit), respectively, are transmitted to the third and second inputs of the discrete information transceiver 8. The information is modulated in a modulator 85, for example, by a BI signal and through an output device 84, a second 3 switching unit. ATS 5. The first 2 switching unit enters the transceiver of data and documentary information 10.

At the end of the transmission of data or documentary information, subscribers can switch to telephone mode by pressing the corresponding buttons in the switching unit of the mode input unit (see Fig. 8 to 4). In this case, the transceiver of data and documentary information transmits the Telephone command, which is allocated by the analyzer 910 of the analysis unit 9, due to which the signal is removed from the first and second outputs of the signal analysis unit, and the third switching unit is set to a state in which the RPU b is again included in the information path. After that, the subscribers using the first 2 switching unit, having fed a signal to the second 12 control input of the system, disconnect the data transceiver 10 from the information path and connect the telephone 1, as a result of which it is possible to conduct classified telephone conversations.

Thus, the inclusion of a cryptographic unit and RPU in the channel field of the PBX made it possible to use these blocks in the mode of mass (group) customer service, which in turn reduced the total amount of equipment required by times, where A is the number of information sources connected to the subscriber side of the PBX. a k is the number of communication channels connected to the channel side of the exchange. In addition, the opportunity to concentrate security equipment in one place (room) made it possible to significantly reduce operating costs (repair, security, maintenance, delivery and storage of key information, and so on), which generally makes it possible to organize a more reliable and cheap communication system.

1. Confidential communication device Certificate No. 8194 for utility model

2. Confidential communication device Certificate No. 7568 for utility model

3. Confidential communication device Certificate No. 11642 for utility model

4. Transceiver duplex communication system Certificate No. 10965 for utility model

5. Confidential communication system. Application No. 2000103721 of February 25, 2000.

6.I.M. Gubenko, E.V. Kuchumov. Telephone sets and payphones Moscow, Tadio and communications, 1981

1. C. L. Tarasova, A. Korneev. TTS transmission systems. Moscow, Radio and Communications, 1981

8.Goryunov V.A., Kolesnikov A.V., Kotov V.I., Troshanov V.A. Device synchronization and decoding. Application No. 2000114448 dated June 19, 2000

9. Catalog Digital and analog microcircuits, part 1. Moscow, Central Design Bureau Dayton, 1999.

3U & 004№lS4

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Sources of literature

Claims (1)

A classified communication system comprising a telephone, a data transceiver, an automatic telephone exchange, a speech-converting device, a first, second and third switching unit and a cryptographic unit, the input and output of the telephone being connected respectively to the first output and input of the first switching unit, the second input and the output of which is connected respectively to the output and input of the data transceiver, the signal input and output of the secret communication system are connected respectively to the control input and the output of the automatic telephone exchange, the first information and clock output of the speech-converting device are connected respectively to the first and second inputs of the third switching unit, the first output of which is connected to the first information input of the cryptographic unit, connected by the second information output and input, respectively, to the information output and input of the secret communication system, characterized in that a discrete information transceiver and a signal analysis unit are introduced into it, wherein the first and second the control inputs of the secret communication system are connected respectively to the first and second control inputs of the first switching unit, the third output and input of which are connected respectively to the first input and output of the automatic telephone exchange, the second input of which is connected to the output of the second switching unit, and the second output to the first the input of the transceiver of discrete information and the information input of the speech-converting device, the second information output of which is connected to the first input of the second switching unit, and the second information and first clock inputs, respectively, to the third information and first clock outputs of the cryptographic block, the second clock and third information outputs of which are connected respectively to the second and third inputs of the digital transceiver, the fourth input of which is connected to the second output of the third switching unit, the first and the second outputs, respectively, with the second input of the second switching unit and the fourth input of the third switching unit, the third output with the third input is a third its switching unit and the first input of the signal analysis unit, the fourth output is with the first clock input of the cryptographic unit and the fifth input of the signal analysis unit, and the fifth output is with the second clock input of the cryptographic unit and the second input of the signal analysis unit, the first and second outputs of which are connected respectively to the control inputs of the second and third switching units, and the third and fourth inputs, respectively, to the control output of the automatic telephone exchange and the signal input of the secret communication system.