JPS62154829A - Voice concealing communication system - Google Patents

Abstract

PURPOSE:To remove the generation of an error due to cipher pull-out even if instantaneous quality deterioration such as hit is generated in a transmission line by transmitting cipher synchronizing information prior to the start of communication to synchronize a voice concealing communication system, and then self-traveling a block cipher unit on the receiving side on the basis of self- synchronization during the transmission and operation of voice cipher data. CONSTITUTION:Prior to the transmission of cipher data, data of n bits in an output n-bit shift register 6 are sent to an input n-bit shift register in each bit and stored in an input n-bit shift register 9 on the receiving side 2', and during the transmission and operation of the voice cipher data, the block cipher unit 10 on the receiving side 2' is self-traveled on the basis of the self- synchronization. Since the cipher synchronizing information is transmitted prior to the start of the voice concealing communication and the block cipher unit 10 in a deciphering device 2' is self-traveled on the basis of the self- synchronization after starting the voice concealing transmission, the generation of an instantaneous trouble in a transmission line 3 does not exert influence upon the cipher synchronizing information and the influence is not spreaded.

Description

[Detailed Description of the Invention] [Summary] To synchronize the voice secret communication method, cryptographic synchronization information is transmitted before the start of communication, and during subsequent voice encrypted data transmission operation, the block cipher on the receiving side is self-enabled. It is designed to run freely in synchronization, so that in the event of an instantaneous failure in the transmission path, errors due to loss of synchronization will not spread.

[Industrial Field of Application] The present invention relates to an improvement in a confidential voice communication system for communicating by encrypting voice.

The cryptographic synchronization information used in the audio secret communication method does not have redundancy like voice signals, so even if there is a momentary failure in the transmission path, this cryptographic synchronization information will not be momentarily interrupted, resulting in errors due to loss of synchronization. It is desirable not to cause any repercussions.

[Conventional technology]

Figure 3 is a block diagram of a conventional audio secret communication system;
The figure is a time chart for the case of FIG.

In the figure, 1 is an encryption device, 2 is a decryption device, 3 is a transmission path, and 4
．． 9 is an input 64-bit shift register, 5.10 is a block cipher, 6 and 11 are output 64-bit shift registers, 7.13 is an exclusive OR circuit, 8 is a cipher synchronization information adder, and 12 is a cipher synchronization information extractor. Show the vessel.

In the case of conventional voice secret communication, as shown in FIG. 4, for each frame, one bit is input as cryptographic synchronization information from the output 64-bit shift register 6 of the encryption device 1 shown in FIG.
It is sent to the 4-bit shift register 4 and added to the ciphertext by the cipher synchronization information adder 8, and then sent to the transmission line 3. It is input to the input 64-bit shift register 9 of the decoding device 2 via the cryptographic synchronization information extractor 12, and then the exclusive OR of the audio signal and the contents of the output 64-bit shift register 6 is sent to the exclusive OR circuit 7. , it becomes a ciphertext, is sent to the exclusive OR circuit 13 via the transmission line 3, is exclusive ORed with the contents of the output 64-bit shift register 11, and is output as a decoded audio signal. be done.

Each time encryption synchronization information is input to the input 64-bit shift register 4.9 on both the encryption device 1 and decryption device 2 sides, the stored signal is shifted one bit at a time, and this shifted content is transferred to the block encryption device 5. 10, a random number sequence is created, and sent to the output 64-bit shift register 6.11, and the ciphertext obtained by exclusive ORing the contents of the output 64-bit shift register 6 and the audio signal is On the decoding side, exclusive OR with the contents of the output 64-bit shift register 11 is performed to decode the original audio signal.

[Problem that the invention seeks to solve]

However, during confidential voice communication, as shown in Figure 4,
For example, if a momentary interruption occurs in the transmission line 3 at an i frame because the cryptographic synchronization information is sent every frame,
The cipher synchronization information does not go to the decryption side, and the cipher synchronization is lost. This loss of synchronization spreads until the i+63rd frame when the contents of the input 64-bit shift register 4.9 are replaced, and during this period, there is a problem that the cipher text cannot be decrypted. be.

[Means for solving problems]

As shown in FIG. 1, before sending the encrypted data, the data in the output n-bit shift register 6 is sent one bit at a time to the input n-bit shift register 4, and at the same time, the data is sent to the input n-bit shift register 4. The voice secret communication system of the present invention is configured such that the data is transmitted so as to be stored in the n-bit shift register 9, and the block cipher 10 of the decryption device 2' runs by itself in self-synchronization during the subsequent voice encrypted data transmission operation. Solved by

[Effect]

According to the present invention, the cryptographic synchronization information is transmitted before the start of secure voice communication, and when the secure voice communication starts, the block cipher 10 of the decryption device 2'' runs by self-synchronization. Even if a momentary failure occurs in the transmission path 3, the cryptographic synchronization information will not be affected, and this effect will not spread.

〔Example〕

FIG. 1 is a block diagram of a confidential voice communication system according to an embodiment of the present invention, and FIG. 2 is a time chart for the case of FIG.

In the figure, 1° is the encryption device, 2° is the decryption device, SWl, S
W2. SW3 indicates a switch, and the same reference numerals indicate the same functions throughout the drawings.

In the case of Figure 1, the switch SWI is
, SW2. SW3 is connected to the solid line side, and 1 bit of the output 64-bit shift register 6 on the encryption device 1 side is input as cryptographic synchronization information to the input 64-bit shift register 4.
It is also sent to the input 64-bit shift register 9 on the decoding device 2'' side and is stored therein.

When this operation is repeated 64 times as shown in Figure 2,
The contents of the input 64-bit shift register 4 on the encryption device 1' side are the same as the contents of the input 64-bit shift register 9 on the decryption device 2' side.

At this time, switches SWI, SW2. Connect SW3 to the dotted line side and secure voice communication begins.

In this case, the encryption synchronization information is not sent, but the output 64-bit shift register 11 of the decryption device 2' side is sent one bit at a time to the input 64-bit shift register 9, and the contents are sent to the block cipher 10 to generate a random number sequence. occurs, output 64
It is sent to the bit shift register 11 and enters a synchronized self-running state that operates in the same way as the encryption bag W1' side.

In this state, for example, even if a momentary interruption occurs in the transmission line 3 at the i-th frame shown in Figure 2, the encryption synchronization information will not be affected, so only the decoded audio of this i-frame will be affected. It will not affect.

〔Effect of the invention〕

As explained in detail above, according to the present invention, even if instantaneous quality deterioration such as momentary interruption occurs in the transmission path, it is possible to eliminate the spread of errors due to loss of cryptographic synchronization.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a confidential voice communication system according to an embodiment of the present invention, FIG. 2 is a time chart for the case of FIG. 1, FIG. 3 is a block diagram of a conventional confidential voice communication system, and FIG. is a time chart for the case of FIG. In the figure, 1.1" is an encryption device, 2.2" is a decryption device, 3 is a transmission line, 4.9 is an input 64-bit shift register, 5.10 is a block cipher, 6.11 is an output 64 A bit shift register, 7.13 is an exclusive OR circuit, and SWI, SW2 and SW3 are switches.

Claims (1)

[Claims] The data of the input n-bit shift register (4) is input to the block cipher (5), becomes a random number sequence, and is input to the output n-bit shift register (6), and this output is the normal voice In a voice secret communication method in which exclusive OR (7) is taken with the data and output as encrypted data, the input n-bit shift register (4) is sent bit by bit to the input n-bit shift register (4). The data in the shift register (6) is sent one bit at a time to the input n-bit shift register (4), and is also transmitted so as to be stored in the input n-bit shift register (9) on the receiving side (2'). Receiving side (2') during voice encrypted data transmission operation
A voice secret communication system characterized in that the block cipher (10) is self-synchronized and runs on its own.