JPH07121006B2 - Confidential device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a secret talk device, and more particularly to a secret talk device that transforms a voice signal at a transmission side and restores it at a reception side.

[Prior Art] In order to prevent a third party from knowing the contents of a call even if the voice signal of the call is intercepted during transmission, the voice signal to be transmitted is transformed by a secret circuit to make it confidential. A secret-talking device is used that is transmitted and the transmitted signal is restored by a secret-restoring circuit to restore the original voice signal.

The highly confidential signal transformation operation method (history scheme) usually uses a time variable for the signal transformation operation. In this case, the confidential circuit and the confidential restoration circuit synchronize the signal transformation operation and the signal restoration operation with each other. Need to The synchronization pull-in time is generally longer in the confidential communication system with high confidentiality. The line connection time becomes longer by this synchronization pull-in time.

The conventional confidential talk device is configured by one secret talk system that satisfies the required high confidentiality.

By the way, the canonicality of the message is used for the third party to restore (decrypt) the encrypted signal. Immediately after the line is connected, extremely standardized messages are exchanged, and there is no important message exchange that requires confidentiality. Also, the regularity of important messages is low. Therefore, most of the information for decryption is obtained from the message immediately after the line connection.

[Problems to be Solved by the Invention]

The above-mentioned conventional secret-talking device has a drawback that if a secret-talking system with high confidentiality is adopted, the line connection time becomes long, and if a line-connecting time is shortened, a secret talk system with low confidentiality must be adopted.

An object of the present invention is to provide a confidential communication device that has high confidentiality for important messages and has a short circuit connection time.

[Means for Solving the Problems]

The confidential data device of the present invention does not require initial value exchange for synchronization with the corresponding confidential data restoration circuit, and does not require initial value exchange for synchronization with the corresponding confidential data restoration circuit. A secret communication means including a second secret communication circuit; a switching means for switching and transmitting a transmission signal from the first secret communication circuit to the second secret communication circuit immediately after the line connection; and an initial stage required for the second secret communication circuit. Means for transmitting the value prior to the time when the first confidential circuit is switched to the second confidential circuit.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the embodiment shown in FIG. 1, a voice encoder 1 for inputting a voice signal 101 and a control signal 201 for inputting call connection information 102
A timer 2 that outputs 202, an initial value setting circuit 3 that receives the control signal 201 and has two output terminals, and a switch 4 that is controlled by the control signal 202 to switch the output signal of the speech coder 1 in two directions. , A secret circuit 5a for inputting one of the switching outputs of the switching 4 and the key signal K1, and a secret circuit for inputting the other switching output of the switching device 4, a signal from one output terminal of the initial value setting circuit 3 and the key signal K2. Circuit 5b, switching device 6 controlled by control signal 202 to selectively output either the output signal of confidential circuit 5a or 5b, and the selected output of switching device 6 and the other output terminal of initial value setting circuit 3 A framing / multiplexing circuit 7 for inputting a signal from the input terminal, a modulator 8 to which an output signal of the framing / multiplexing circuit 7 is input and an output terminal of which is connected to a subscriber line (not shown), and an input end of which is added. Of the demodulator 18 connected to the power line (not shown) A frame synchronization / separation circuit 17 that receives an output signal and has two output terminals and a signal from one output terminal of the frame synchronization / separation circuit 17
Initial value detection circuit 13 having an output terminal and initial value detection circuit
The memory 12 which inputs the control signal 203 which is a signal from one output terminal of 13 and outputs the control signal 204, and the signal from the other output terminal of the frame synchronization / separation circuit 17 which is controlled by the control signal 204 Switch 16 for switching in the direction, a secret output restoration circuit 15a for inputting one switching output of the switch 16 and the key signal K1, another switching output of the switch 16, an initial value detection circuit 1
A secret story restoration circuit 15b that inputs the signal from the other output terminal of 3 and the key signal K2, and a switcher 14 that is controlled by the control signal 204 and selectively outputs one of the output signals of the secret story restoration circuit 15a or 15b. , And a voice decoder 11 which inputs the selected output of the switch 14 and outputs a voice signal 103.

The secret story restoring circuit 15a corresponds to the secret story circuit 5a, and the secret story restoring circuit 15b corresponds to the secret story circuit 5b.

Immediately after the line connection, the confidential communication circuit 5a and the confidential communication restoration circuit 15a are used, and after a certain period of time, the confidential communication circuit 5b and the confidential communication restoration circuit 15b are used. Switches 4 and 6 and 16 and 14 are used to make this switch.

As will be described later in detail, the time data and the initial value data are necessary for the confidential data restoration circuit 15b to synchronize with the confidential data circuit 5b. The time data and the initial value data are generated by the initial value setting circuit 3. The framing / multiplexing circuit 7 frames and multiplexes the time data and the initial value data output from the initial value setting circuit 3 and the voice data signal encrypted by the confidential circuit 5a into a data signal of 9600 bps.

FIG. 2 is an explanatory diagram showing the structure of a frame created by the framing / multiplexing circuit 7.

The number of bits in one frame is 192 bits, and the frame rate is (9600 ÷ 192 =) 50 frames / s. When the time slots are sequentially numbered from 0 to 191 from the beginning of each frame, the time bit 0 is assigned to the frame bit F of the fixed pattern for frame synchronization, and the time data bit C1 forming the time data is numbered 1 The initial value data bits that make up the initial value data
The second time slot is assigned to C2. No. 3 to 191
The numbered time slot is assigned to the constituent bits of the encrypted voice data signal output by the confidential circuit 5a (or 5b).

FIG. 3 is a time chart of the call connection information 102 and the control signals 201 to 204.

When the line connection between the subscriber line connected to the modulator 8 and the subscriber line connected to the demodulator 18 is completed, the call connection information 102 rises, at which time the control signals 202 and 204 become the state "0". The switches 4 and 6 are tilted to the side of the confidential circuit 5a, and the switches 16 and 14 are tilted to the side of the confidential restoration circuit 15a.

The voice encoder 1 encodes the voice signal 101 into a voice data signal of 9600 × 189/192 bps with high efficiency, and outputs this voice data signal to the confidential circuit 5a via the switch 4.

The confidential circuit 5a frames the input voice data signal
In the frame unit formed by the multiplexing circuit 7, bits are exchanged in a confidential manner by an exchange pattern based on the key signal K1, and the confidential voice data signal is output to the framing / multiplexing circuit 7 via the switch 6.

The framing / multiplexing circuit 7 converts the speed of the input voice data signal, arranges it in each of the 3rd to 191st time slots of each frame, and outputs it. The signal output from the framing / multiplexing circuit 7 is converted into a modulated signal by the modulator 8 and transmitted, demodulated by the demodulator 18 and input to the frame synchronization / separation circuit 17. The frame synchronization / separation circuit 17 performs frame synchronization with the input signal, speed-converts the bits of each time slot from No. 3 to No. 191 of each frame into a continuous audio data signal, and restores the secret story via the switch 16. Output to the circuit 15a.

The confidential data restoration circuit 15a reverses the bit exchange performed by the confidential data circuit 5a to the input voice data signal to restore the voice data signal before the encryption by bit exchange and restore the voice data via the switching device 14. Output to the device 11.

The voice decompressor 11 decodes the input voice data signal and outputs it as a voice signal 103.

On the other hand, the timer 2 raises the control signal 201 when the time t _{1 has} elapsed after the rise of the call connection information 102. This time t ₁ is the demodulator 18
And frame synchronization / separation circuit for modulator 8
It is a time required for 17 frame synchronization to be established, and is usually about 1 to 2 seconds.

The initial value setting circuit 3 is activated by the rising edge of the control signal 201 and generates 255-bit time data and 85-bit initial value data of one pattern of the M series whose repetitive synchronization is 2 ⁸ −1 = 255. To do. Time data bit
C1 and the initial value data bit C2 are respectively placed in the first and second time slots of each frame by the framing / multiplexing circuit 7, and the modulator 8, demodulator 18, frame synchronization, and
It is transmitted to the initial value detection circuit 13 via the separation circuit 17 at a rate of 1 bit / frame. The 85 bits of the initial value data C2 are repeatedly transmitted three times at the time t ₂ (= 5.1 seconds) required to transmit all 255 bits of the time data bit C1. The initial value detection circuit 13 receives the initial value data by judging the majority of the input initial value data bits C2 for three times, and at the same time when the reception is completed, the pattern of the time data is detected and the pulse-shaped control is performed. The signal 203 is output, and 85 bits of the received initial value data are transferred to the confidential story restoration circuit 15b. The memory 12 stores the input of the control signal 203 and stores the control signal 2
04 is started up, and the switches 16 and 14 are switched to the secret story restoration circuit 15b side by this rising. The timer 2 also raises the control signal 201 and raises the control signal 202 when time t _{2 has} elapsed after the control signal 201 rises, and the initial value setting circuit 3 causes the initial value data generated by the fall of the control signal 201 to be 85 bits of the initial value data. To the confidential circuit 5b, and the switches 4 and 6 switch to the confidential circuit 5b side by the rise of the control signal 202. As a result, the initial value data is simultaneously input to the confidential talk circuit 5b and the confidential talk restoration circuit 15b except the shift of the transmission delay, and the switches 4 and 6 and 16 and 14 are switched. By using a relatively long pseudo-random pattern for the time data, it is possible to reliably set the time even if there is a considerable transmission bit error.
The initial value data can be surely transmitted by the majority decision for three times.

The confidential circuits 5b and 15b each have a plurality of M-sequence generators. The total number of stages of shift registers of these M-sequence generators is 85 or more, and the configuration of each M-sequence generator is designated by the key signal K2.

The confidential circuit 5b uses the input initial value data of 85 bits for each M
Input as an initial value to each shift register of the sequence generator (when the total number of stages of the shift register exceeds 85, a fixed value is used as the initial value for the excess), and the output pattern of each M sequence generator is synthesized. A pseudo random pattern having a repetition cycle of ²⁸⁵ −1 or more is created, and the voice data signal input from the voice encoder 1 via the switch 4 is scrambled with this pseudo random pattern and output in a secret manner. The encrypted voice data signal is input to the framing / multiplexing circuit 7 via the switch 6, and the modulator 8, demodulator 18, frame synchronization / separator are used by using the time slots 3 to 191 of each frame. Secret story restoration circuit 1 via circuit 17 and switch 16
It is transmitted to 5b. The secret story restoration circuit 15b creates a pseudo random pattern in synchronization with the pseudo random pattern created by the secret story circuit 5b in the same manner as the secret story circuit 5b, and descrambles the voice data signal from the switch 16 with this pseudo random pattern. Restore the voice data signal before encryption. The restored voice data signal is input to the voice encoder 11 via the switch 14 and decoded into the voice signal 103.

The voice data signal encrypted by the confidential circuit 5b is scrambled by a pseudo-random pattern with an extremely long repeating period, and does not contain many highly-formed messages immediately after the line is connected. Decoding is extremely difficult.

In the embodiment shown in FIG. 1, the time data pattern and the initial value data are transmitted in parallel, and the transmission is completed at the same time. However, the time data pattern and the initial value data may be transmitted in tandem. You can also When the time data pattern is transmitted first, another timer is provided between the initial value detection circuit 13 and the memory 12 to transfer the initial value data to the confidential circuit 5b and the confidential communication restoration circuit 15b, and a switch. Four,
It is necessary to wait for the switching of 6, 16 and 14 until the transfer of the initial value data is completed.

The embodiment of the present invention has been described above in the case where the voice signal is coded into the voice data signal and then encrypted. However, the same effect can be obtained by using the present invention also when the voice signal is analogized. Obtainable.

〔The invention's effect〕

As described above, the present invention is provided with a plurality of confidential talk means and a switching means for switching these secret talk means,
Immediately after the line is connected, the connection can be shortened or the connection time can be shortened by using a secret communication method that does not require the synchronization, and after the line connection, fixed message exchanges are completed, and during this time a highly confidential conversation is possible. When the synchronization of the means is established, there is an effect that it is possible to sufficiently protect the important message exchanged after switching to the secret communication means after the line connection for a while from the decryption by a third party.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory view showing the structure of a frame formed by the framing / multiplexing circuit 7 in the embodiment shown in FIG. 1, and FIG. 3 is the same call connection. 3 is a time chart of information 102 and control signals 201 to 204. 1 ... Speech encoder, 2 ... Timer, 3 ... Initial value setting circuit, 4,6,14,16 ... Switcher, 5a, 5b ... Secret circuit, 7 ...
… Frame conversion / multiplexing circuit, 8 …… Modulator, 11 …… Voice decoder, 12 …… Memory, 13 …… Initial value detection circuit, 15a, 15
b …… Secret story restoration circuit, 17 …… Frame synchronization / separation circuit, 1
8 ... Demodulator.

Claims (1)

[Claims] Claims: 1. A first secret circuit which does not require initial value exchange for synchronization with a corresponding secret story restoring circuit and a second which requires initial value exchange for synchronizing with a corresponding secret story restoring circuit.
And a switching means for switching and transmitting a transmission signal from the first confidential circuit to the second confidential circuit immediately after the line connection, and an initial value required for the second confidential circuit. And a means for transmitting prior to the time when the first confidential circuit is switched to the second confidential circuit.