JPH0677952A - Secret talk transmitter - Google Patents

Abstract

PURPOSE:To provide a secret talk transmitter which generates a ciphering code from the contents of plural stored slots in the case of cable or radio data communication for transmitting data decomposed into the unit of a slot. CONSTITUTION:On the transmission side, n-th bit data of stored digital data decomposed for the unit of a slot are stored in a shift register 4 by an n-th bit select circuit 3, and the ciphering code is generated by a ciphering code generating circuit 6. Further, the ciphering code generated there and the digital data extracted from a memory cell 1 are logically calculated and turned to secret talk. Afterwards, the ciphering code is extracted from the n-th bit of the received and stored digital data on the reception side, and decoding logical arithmetic is performed in the inverse order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes it possible to easily know the contents of communication by a third party other than the sender or the receiver when transmitting by wire or wireless communication for digital data divided into slots. The present invention relates to a confidential transmission device intended to prevent gains.

[0002]

2. Description of the Related Art In a conventional confidential communication transmission device, a portion corresponding to an encryption code is set on the subscriber side and an exclusive OR is taken to decrypt the encrypted data (for example, Japanese Patent Laid-Open No. 63-237633). (See the official gazette).

[0003]

However, in the conventional system as described above, if the encrypted code becomes clear for some reason, the decryption can be uniquely performed. There was a chipped surface. Therefore, an object of the present invention is to provide a low-cost confidential communication transmission device that improves the above problems and has a hardware configuration that can be realized by an existing semiconductor device.

[0004]

In order to achieve this object, the confidential transmission apparatus of the present invention uses a cryptographic logical operation by extracting a cryptographic code from an n-th bit data string of a slot of accumulated data on the transmitting side. The receiving side has an encryption code extracting means for generating an encryption code for performing the decoding from the stored data itself, and the receiving side generates an encryption code for a decryption logical operation based on the n-th bit data string of the received stored data. It has a configuration including an encryption code restoring means for performing.

[0005]

According to the present invention, in the above construction, the fact that the nth bit of the data divided into slot units has a low correlation with the nth bit of the next data is used as the encryption generation code for the encryption logical operation. Therefore, at the time of decryption, the encryption code for decryption is obtained when all the data used for generating the encryption code are available.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the confidential transmission apparatus of the present invention will be described below with reference to the drawings. The components of FIG. 1 will be described. On the transmitting side, 1 is a storage element for accumulating data, 2 is an address generation circuit for controlling writing or reading of data in the storage element, and 3 is divided into slots. The n-th bit select circuit for selecting the n-th bit from the selected data and generating the clock for controlling the writing of the value to the shift register 4, and 6 is a timing based on the n-th bit data string obtained by the shift register 4. An encryption code generation circuit that executes a logical operation at the timing of the generation circuit 5 to generate an encryption code, and 7 is based on the encryption code generated by the encryption code generation circuit 6 for the data read from the storage element 1. An encryption circuit that performs an encryption logical operation according to the timing of the timing generation circuit 5, and 8 is suitable for a transmission medium because the encrypted data is transmitted by the transmission medium. Modulation circuit for modulating the, 9 is a transmission circuit for transmitting by converting electric signals radio waves. The nth bit select circuit 3
The shift register 4 and the encryption code generation circuit 6 together form an encryption code extraction means.

Next, on the receiving side, 10 is a receiving circuit that receives radio waves and converts them into electric signals to correct errors that occur during transmission and reception, and 11 demodulates the modulation applied by the modulation circuit 8 and outputs from the encryption circuit 7. A demodulation circuit for reproducing encrypted data equal to, a storage element 12 for storing demodulated data,
Reference numeral 13 denotes an address generation circuit and timing generation circuit for controlling writing or reading of data in the storage element 12, and 14 selects an encryption code component at the nth bit from the data divided in slot units and shifts it to the shift register 15. An nth bit select circuit for generating a clock for controlling the writing of the value, 17 is a shift register 15
An encryption code decoding circuit that reproduces the n-th bit data string from the encryption code obtained in step 18 is based on the encryption code that the encrypted data read from the storage element 12 is reproduced by the shift register 15. This is a decoding circuit that performs a decoding logical operation at the timing of the timing generation circuit 16. The nth above
The bit select circuit 14, the shift register 15, and the encryption code decoding circuit 17 together form an encryption code restoring means.

[0008] The constituent elements as described above will be described. Next, the mutual relation and operation of the constituent elements will be described. The transmitting side inputs the data decomposed into the storage element 1 and the shift register 4 in slot units. The storage element 1 is controlled by the address generation circuit 2 and stores data at a predetermined address. On the other hand, the nth bit of the data input to the storage element 1 is sequentially input to the shift register 4 at the timing controlled by the nth bit select circuit 3. Eventually, when the input of data for the number of stages of the shift register is completed, the n-th bit data string necessary for the encryption code generation in the encryption code generation circuit 6 is obtained, and its logical conversion is as shown in FIG. Bit inversion, rearrangement of the bit string shown in FIG.
An encryption code is generated by using the storage element shown in FIG. 6A, by a logical operation with a user-defined encryption code shown in FIG. 6B, or by a combination thereof.
The timing is controlled by the timing generation circuit 5, and when the generation of the encryption code is completed, the encryption circuit 7 performs a logical operation with the data read from the storage element 1, and the data of the nth bit is the encryption code. The data encryption is completed by using itself.

Here, as the method of the logical operation of the encryption circuit, as shown in FIG. 7, the data from the storage element 1 and the encryption code generated by the encryption code generation circuit 6 are exclusive ORed and encrypted. Method is available. The encrypted data is subjected to modulation suitable for the transmission medium in the modulation circuit 8 and converted into radio waves in the transmission circuit 9 for transmission.

On the receiving side, the receiving circuit 10 receives a target radio wave, amplifies it to an appropriate level, corrects a transmission error occurring between transmission and reception, and sends it to the demodulation circuit 11, where it is input to the modulator 8. Reproduce data equal to the time point. The storage element 12 is controlled by the address generation circuit 13 and stores data at a predetermined address. On the other hand, the nth bit of the data input to the storage element 12 is set to the nth bit select circuit 14
Are sequentially input to the shift register 15 at the timing controlled by. Eventually, when the input of data for the number of stages of the shift register is completed, the n-th bit data string required for decoding is obtained at the output, and the n-th bit data string and the storage element 12 are obtained.
Decoding circuit 1 for exclusive logic operation with data read from
8 and the n-th bit data string itself is decrypted by the encryption code decoding circuit 17 by a method corresponding to FIGS. 5 (a), 5 (b), 6 (a) and 6 (b), and is input to the storage element 1. The reconstructed data. The timing is the timing generation circuit 1
Controlled by 6.

In the above embodiment, the case of wireless communication has been described, but it goes without saying that it is also applicable to wired communication. Further, as the n-th bit data string extracting means on the transmitting side, in the above description, the extraction of the n-th bit data string is input to the shift register 4 in parallel with the storage in the storage element, but instead, as shown in FIG. After being once stored in the storage element, the n-th bit data string may be selectively extracted from it. Further, as shown in FIGS. 3 and 4, the n-th bit extraction circuit 19 including an address decoder and a latch is used as a detection means for detecting the address of the data input to the storage element 1 or the address of the data stored in the storage element 1. Data may be selectively extracted. As a matter of course, the n-th bit data string extracting means on the receiving side may also use the configuration mentioned on the transmitting side or a combination thereof.

In the case of FIGS. 3 and 4, the encryption code extracting means is composed of the nth bit extracting circuit 19 and the encryption code generating circuit 6, and the encryption code restoring means is the nth bit extracting circuit 1.
9 and the encryption / decryption circuit 17.

Further, the nth bit select circuits 3 and 14 on the transmitting side and the nth bit extracting circuit 19 on the receiving side are controlled by an external control signal so that "n" of the nth bit can be arbitrarily changed. If so, the confidentiality can be further enhanced.

[0014]

As described above, according to the present invention, an encryption code is generated by using a plurality of slot unit data, an encryption logical operation is performed, and all data used in the encryption code generation is generated. Since it cannot be decoded unless the transmission is completed correctly, it is possible to realize a confidential transmission device that has highly accurate confidentiality and does not increase the amount of information to be transmitted.

[Brief description of drawings]

FIG. 1 is a block diagram of a confidential transmission device according to an embodiment of the present invention.

FIG. 2 is a block diagram of another embodiment.

FIG. 3 is a block diagram of another embodiment.

FIG. 4 is a block diagram of yet another embodiment.

FIG. 5 (a) is a logic diagram of an encryption code generation circuit by similarly inverting each bit thereof. (B) is a logic diagram of an encryption code generation circuit by similarly rearranging the bit strings.

FIG. 6A is a logic diagram of an encryption code generation circuit that also uses the storage element; FIG. 6B is a logic diagram of an encryption code generation circuit that also uses a logical operation with the encryption code defined by the user.

FIG. 7 is a logic diagram of the encryption circuit of the same.

[Explanation of symbols]

 1 Storage Element 2 Address Generation Circuit 3 nth Bit Select Circuit 4 Shift Register 5 Timing Generation Circuit 6 Encryption Code Generation Circuit 7 Encryption Circuit 8 Modulation Circuit 9 Transmission Circuit 10 Reception Circuit 11 Demodulation Circuit 12 Storage Element 13 Address Generation Circuit 14 Nth bit select circuit 15 shift register 16 timing generation circuit 17 encryption code decoding circuit 18 decoding circuit 19 nth bit extraction circuit

Claims (6)

[Claims] 1. A storage device at a transmitting side, an address generation circuit for controlling writing and reading of the storage device, and an encryption for extracting an n-th bit data string from input data and generating an encryption code by a logical operation. Code extraction means,
An encryption circuit for performing an encryption logical operation on the data read from the storage element based on the encryption code generated by the encryption code extraction means, and the output data of the encryption circuit on the receiving side. A storage element that stores the data, an address generation circuit that controls writing and reading of the storage element, a decoding circuit that performs decoding using the nth bit data string of the demodulated data, and the nth bit data string. That is, it has an encryption code restoring means circuit for decoding the encryption code itself, and the transmitting side extracts the n-th bit data string of the data divided and accumulated in slot units as the encryption generation code by the encryption code extracting means. And perform an encrypted logical operation,
A secret-speech transmission apparatus configured so that the receiving side extracts an encryption code from the n-th bit data string of the slot received and accumulated by the encryption code restoring means and performs a decryption logical operation. 2. The n-th data from the input data or the data once stored in the storage element via a shift register.
The confidential transmission device according to claim 1, which extracts a bit data string. 3. The confidential transmission apparatus according to claim 1, wherein the n-th bit data string is extracted by using the address of the data input to the storage element as the detection means. 4. The confidential transmission apparatus according to claim 1, wherein the n-th bit data string is extracted by using the address of the data stored in the storage element as the detecting means. 5. The secret channel transmission device according to claim 1, wherein a storage element is used in a portion for performing a logical operation of the encryption code generation circuit of the encryption code extraction means or the encryption code decoding circuit of the encryption code restoration means. 6. The confidential transmission device according to claim 1, wherein the number of the data bit of the transmitting side and the receiving side to be extracted can be changed by a control signal from the outside.