JPS62173834A - Special code generating system - Google Patents

Abstract

PURPOSE:To prevent the deviation of synchronism of a special code even in case of bit deviation between transmission data and reception data by detecting a signal indicating the divisions of data blocks and generating the special code by this signal to decode a cipher. CONSTITUTION:Ciphered reception data is inputted from an input terminal 11 and is inputted to a block signal generating part 1 and an exclusive OR circuit 3. The generating part 1 monitors a block division signal in reception data and detects this signal to output a block signal 101. At the time of receiving the block signal 101, a special code generating circuit 2 generates the decoding special code within a time shorter than a time corresponding to the length of one block. The special code generated by this circuit 2 is inputted to the exclusive OR circuit 3 for the purpose of decoding ciphered data in the next block.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention transmits data on a data communication line having a frame structure after encrypting it using a special code, and restores the original data on the receiving side. This invention relates to a reception jlljl special code generation method for a cryptographic device.

(Prior art) Since JJC, data communication has had problems such as information leakage, so in order to ensure confidentiality, the transmitted data is specially converted with an encryption device, and the transmitted data is encrypted (as a hidden signal). On the 6 receiving side, which is on a public road, this is inversely converted and restored to its original state, and the received data is output.

Here, the use of special codes is generally widely used as a means of encryption.

For example, there is a method in which the special code generated in the encryption device and the transmitted data are exclusive-ORed to perform the encryption. Reception 1
According to the rules, a special code that is the same as the special code generated on the transmitting side is generated, and the original data is inverted by exclusive ORing this with the encrypted data.In this case, the receiving side As a special code, data cannot be restored unless the special code used at the time of encryption 1 and the special code used on the sending side at the same time are used. .

A similar operation is performed to match the special codes on the sending and receiving sides.

Further, the conventional special code generation system is a so-called 1-bit asynchronous system in which a special code is generated 1 bit at a time according to a clock indicating the timing of data.

(Problem to be solved by the invention) For this reason, the received data does not respond to the transmitted data! There was a drawback that whenever a deviation occurred, the synchronization of the special code would be lost. In other words, in general data lines, there are frequent opportunities for bit shifts to occur due to various causes such as instantaneous interruptions, phase jitter, and noise contamination, and each time, the synchronization of special codes is lost, and as a result, However, there is a problem in that the synchronization operation is frequently performed.

However, if this synchronization operation is performed frequently, it will cause serious trouble to the communication line. During a synchronization operation, it is necessary to put a synchronization signal on the line, which not only causes the data to be stopped, but also allows a third party to successfully break the code by analyzing the synchronization signal flowing on the line. This is because there is a risk of causing

One way to solve this problem is to improve the quality of the line in use, but it is usually unlikely that this can be easily implemented. SUMMARY OF THE INVENTION An object of the present invention is to provide a special code generation system in which the synchronization of special codes is not disrupted even when the above-mentioned deviation force occurs in order to resolve the problem described above.

(Means for Solving the Problems) The present invention has the following means configuration to achieve the above object. That is, the special code generation method of the present invention is a special code generation method for decoding on the receiving side when communication data is encrypted using a special code and transmitted/received, and is a special code generation method for decoding the data in the received input data. a block signal generating circuit that monitors a signal indicating the block signal, and outputs a pro-y signal indicating the time position of the pro-c break in accordance with the signal; A special code generation circuit that generates a predetermined special code for decoding to be used within one block in a time shorter than the time equivalent to one block length for each block; This is a special code generation method.

(Function) The function of the special code generation system of the present invention will be explained below. The disadvantage of the prior art is that the special code generation system is a so-called 1-pitch start-stop synchronization system in which a special code is generated bit by bit in accordance with a clock indicating the timing of data.

Therefore, in order to solve the above problem, the generation of special codes on the receiving side is divided into blocks, the timing of special code generation is set at the block break, a so-called asynchronous system is used for each block, and one block It can be seen that the time required to generate the special code can be made shorter than the time required for one block minus the time corresponding to the amount of bit shift expected to occur within one block.

Therefore, in the method of the present invention having the above-described means, the block signal generation circuit monitors the received input data, and generates a block signal as a timing signal every time it detects a signal indicating a data block division. Send to special code generation circuit.

The special code generation circuit receives this block signal and generates the special code necessary for decoding the received data within one block within a time shorter than one block. Therefore, if the generated special code is used in a block after the next data block (for example, the immediately next data block), a bit shift corresponding to the shortened time will occur, and the interval between block signals will change by that amount. However, the received data and special code for each block can be completely synchronized.

Therefore, if a special code is generated in a short period of time corresponding to the bit shift that is expected to occur, complete decoding can be performed without being affected even if a bit shift occurs. become.

(Implementation PA) Next, the present invention will be described in detail with reference to drawings showing examples. FIG. 1(a) is a block diagram showing the configuration of an embodiment of the special code generation method according to the present invention, and FIG.
) is the timing chart. The block diagram of FIG. 1(a) conceptually shows the receiving circuit of the encryption device, in which received data in an encrypted form transmitted via a communication signature is input from the input terminal 11, The signal is input to block signal generation circuit 1 and exclusive OR circuit 3.

The block signal generation circuit 1 monitors a signal indicating a block break in the received data series, and outputs the following signal:
A block signal 101 indicating the block break position is output. This block signal 101 is input to the special code generation circuit 2.

In this embodiment, a frame signal in the data series is used as a signal indicating a block break in the data series. That is, in general data communication, a frame structure is often employed to distinguish various types of data in a data series.

For example, the PCM-24 system is famous.

Therefore, the data length divided by the frame signal or n times the data length may be determined as one block. The special code generation circuit 2 receives the block signal 101 as a trigger signal for generating a special code, and receives the block signal 101 as a trigger signal for generating a special code.
) A special code is generated at the timing shown in timing chart 1.

The special code generated here is used within the first block.5 Also, the time required to generate the special code is shorter than the time of one block length, as shown in the timing chart.

That is, if the block length is m bits, then n1 bits I-
The time required to generate the special code is equivalent to (m-t) bit length.

However, when the special code of mbi11 generated by the special code generation circuit 2 is used to restore encrypted received data in the next block, the speed of the received data series is output from the special code generation circuit 2 at the same speed as .

Therefore, when the exclusive OR circuit 3 performs the exclusive OR of the received data and the special code, the timings of both will match exactly, and the received data will be restored accurately. become. The restored received data is output from the output terminal 12.

Here, the above numerical value is set to a value larger than the amount of bit shift expected to occur within one block, and the operating clock of the special code generation circuit 2 is m
A bit special code that can be generated within a time period of (m-L) bit length is selected and set. By using this method, when a bit shift as shown in FIG. 2(a) occurs, the special code output 23 will be used from the middle of the special code output 22. It can be seen that the synchronization will not be lost.

In addition, if a bit shift as shown in FIG. 2(b) occurs, after using all the special code outputs 25,
It can be seen that although the idle time 27 occurs, the synchronization of the special code at the time the special code output 26 is used does not collapse.

(Effects of the Invention) The special code generation method according to the present invention uses the so-called start-stop synchronization method for each block in which the timing of special code generation is set for each block by the means structure and operation explained above. The time required to generate a special code for a block is 1
Since the time is set shorter than the time for a block minus the time equivalent to the amount of bit deviation that is expected to occur within one block, a bit deviation of the received data with respect to the transmitted data has occurred. This has the effect that the synchronization of the special code does not collapse even in the case of a special code, which greatly contributes to the efficient operation of encrypted communication lines and communication security.

[Brief explanation of drawings]

FIG. 1(a) is a block diagram showing the configuration of an embodiment of the present invention, FIG. 1(b) is a timing chart for the configuration of FIG. 1(a), and FIG. 2 is a case where a bit shift occurs. 3 is a timing chart illustrating the operation of FIG. 1...Block signal generation circuit, 2...
・Special code generation circuit, 3...Exclusive OR circuit, 11...Input end, 12...Output end, 21-26...Special code Output, 27...
...Playtime Agent Patent Attorney Yoshihiro Yahata (a) (b) Kibatsu Hitachi, Fl'l's J Intervention and Film Seven Etobi...
Throat size - 7913 glue

Claims (1)

[Claims] This is a special code generation method for decoding on the receiving side when communication data is encrypted using a special code and sent/received, and the method monitors a signal indicating a block division of data in received input data and divides the block according to the signal. a block signal generating circuit that outputs a block signal indicating the time position of the block signal; upon receiving the block signal from the block signal generating circuit, a predetermined special code for decoding to be used within one block is assigned to each block of received data; A special code generation method comprising: a special code generation circuit that generates a special code in a time shorter than a time corresponding to one block length;