JPH04114531A - Data communication system - Google Patents

Abstract

PURPOSE:To prevent the interception of data by providing cover means which cipher data transferred on a communication line and which decode data between a pair of data communication equipments transmitting/receiving data. CONSTITUTION:A transmission system consists of a cover circuit 1a in a master station 31, a data communication equipment 23a, a port disk 21a in the data communication equipment 23a and a data terminal equipment 401 connected to the master station 31. A reception system consists of a cover circuit 1b in a slave station 34, a data communication equipment 23b, a port disk 21b in the data communication equipment 23b and a data terminal equipment 411 connected to the slave station 34. When plural data communication equipments transmit and receive data through the common communication line, the cover means 1a and 1b cipher data transferred on the communication line and data is restored and is communicated between a pair of the data communication equipments transmitting and receiving data. Thus, the interception of data is prevented.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a data communication system in which a plurality of data communication devices transmit and receive data via a common communication line, and particularly relates to a data communication system that prevents data interception. Regarding the system.

[Prior Art] A conventional communication system of this type will be described below with reference to the drawings.

FIG. 2 is a diagram showing a connection state of a conventional multidirectional multiplex wireless data communication system using a time division multiplexing/time division multiple access system.

In the figure, a slave station 34 and a relay station 32 are connected to a master station 31, and two slave stations 33 and 35 are further connected to the relay station 321.

These master stations 31. Relay station 32 and slave station 33゜3
4.35, the data terminal devices 401 to 4 are connected as shown in the figure.
05 411 to 415 are connected, and now data terminal devices with the same lowest digit, such as between data terminal devices 401 and 411 and between data terminal devices 402 and 412, are connected to the master station 31. and slave station 34 or between master station 3
1 and relay station 32 are communicating.

Between the master station 31 and the relay station 32, between the master station 31 and the slave station 34,
Wireless lines 3 are connected between the relay station 32 and slave stations 33 and 35, respectively.
01,302 and 303.304, and in the downstream direction, that is, from the master station to the relay station, from the master station to the slave station, or from the relay station to the slave station, multiple communication channels are simultaneously transmitted for all communication channels. It is sent out all at once by radio waves in the same direction. On the other hand, in the upstream direction, that is, in the direction from the slave station or relay station to the master station, only the communication channel in use is intermittently transmitted by radio waves from the corresponding station in burst mode.

Assuming that the signals passing through the wireless line are communicating in accordance with the communication frame format l-a shown in FIG. 4, each data terminal device has a A communication having a number equal to the lowest digit indicating each data terminal device is assigned a communication channel l shown in 7 frame format d from among the communication channels of communication frame format a in FIG. 4. Suppose a channel is assigned. Then, the wireless lines 301, 302, 303.30 shown in FIG.
Communication channels shown in frame formats b, c, d, and e in FIG. 4 are used in the uplink direction of 4, respectively.

That is, the wireless line 301 uses frame format b.
Communication channel 2. 3. 4. 5 were used,
The wireless line 304 uses a frame former, and a communication channel 3 shown in /e is used. In addition, a control channel for line control is used for all the lines mentioned above.

The downlink wireless lines 301 to 304 all include all the communication channels 1 to 5 described above, and
With respect to the communication channel that uses the data, meaningless data is multiplexed and transmitted.

In the master station 31, relay station 32, and slave stations 33 to 35,
A data communication device 23 shown in FIG. 3 is used.

The data communication device 23 includes m data terminal devices 400.
are each made by data communication! m mounted inside 123
The port board 21 is connected to the port board 21.

Each of the m port boards 21 converts the signal input from the corresponding data terminal device 400 into a signal according to the communication frame format, outputs it onto the transmission data bus 201, sends it to the wireless transceiver board 24, and sends it to the outside. antenna 2
5 as radio waves.

On the other hand, the radio waves received by the antenna 25 pass through the radio transmitter/receiver board 24 and are output onto the reception data bus 202. Each of the m port boards 21 connects to this receiving data bus 2.
Of the received signals on 02, only the signals of the communication channels assigned to each of the corresponding data terminal devices 4.0 to which they are connected are separated and selected and sent to the above-mentioned data terminal devices 4.0.

Each of the m port boards 21 described above is provided with a communication channel selection switch 22 connected thereto. Each of the m port boards 21 described above can select any communication channel by using these communication channel selection switches 22 to perform transmission and reception.

[Problems to be Solved] In the conventional multidirectional multiplex wireless data communication system described above, there is no measure to prevent data communication from being intercepted by subscribers other than the communication partner, and the problem is that data can be easily intercepted. was there.

For example, in the downlink direction, the same data is simultaneously sent in multiple directions, so all relay stations and all slave stations can receive all data. Further, in the uplink direction, for example, the relay station 32 is connected to data terminal devices 414 and 415 connected to the slave station 33 and to the slave station 35 in addition to the data terminal device 412 that directly belongs to the relay station 32. It is also possible to receive data from the data terminal device 413.

Further, when the data communication device 23 shown in FIG. 3 is used, it is also possible to easily intercept the data of communication between other data terminal devices. That is, data communication [23
According to the above, all the port boards share communication data on the receiving side via the reception data bus 202, so each port board 21 can intercept other communication data that is not the target of communication by simply switching the wireless channel selection switch 22. Is possible.

The present invention has been made in view of the above problems, and aims to provide a data communication system that can prevent data interception.

[Means for solving the problem] In order to achieve the above object, the invention according to the first claim provides a data communication device in which a plurality of data communication devices transmit and receive data via a common communication line. This configuration includes a concealment means that encrypts the data transferred and makes it possible to restore the data only between a pair of data communication devices that mutually transmit and receive data.

Further, the invention according to a second claim is the data communication system according to claim 1, wherein the secrecy means includes a storage means for storing an identification code unique to a pair of data communication devices that transmit and receive data; an encryption means for encrypting data when transmitting the data to the communication line based on the identification code stored in the storage means; and an encryption means for encrypting data from the communication line based on the identification code stored in the storage means. and a decoding means for decoding the data when receiving the data, and the data communication device is also configured to include the concealment means.

[Operation] In the invention according to claim 1 configured as described above, when a plurality of data communication devices transmit and receive data via a common communication line, the concealment means is transferred over the communication line. Data is encrypted, and the data is restored and data communication is performed only between a pair of data communication devices that exchange data with each other.

Further, in the invention according to claim 2 configured as described above, in the secrecy means included in the data communication equipment, the storage means stores an identification code unique to a pair of data communication equipment that transmits and receives data, The encryption means encrypts the data when transmitting the data to the communication line based on the identification code stored in the storage means, and the decryption means encrypts the data when transmitting the data to the communication line based on the identification code stored in the storage means. Decodes the data when it is received from the line.

[Example] Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 shows a block diagram of a secret device in a data communication system according to an embodiment of the present invention, in which a data terminal device 401 transmits data to a data terminal device 411 via a wireless line 3. An example of application is shown.

The transmission system is composed of a secret circuit 18 and a data communication device 23a in the master station 31, a port board 21a in the data communication device 238, and a data terminal device 401 connected to the master station 31. The reception system is slave station 3.
4, the secret circuit 1b and data communication device 23b, and the port board 21b inside this data communication device 23b.
Data terminal device 411 connected to this slave station 34
It is made up of. Note that the wireless signal is transmitted through the antenna 25a.
, 25b.

The configurations of the data communication devices 23a and 23b are the same as the data communication device 23 already explained in FIG.
Illustrations of other components such as are omitted.

Although a plurality of port boards 21m in Data Communication Co., Ltd.@23a and port boards 21b in data communication device 23b are normally used, only one is shown as a representative, and the others are omitted. Also, a secret circuit 1a for the transmitting system and a secret circuit 1b for the receiving system.
are connected to each of the port boards 21a and 21b, but the reception system concealment circuit in the master station 31 and the transmission system concealment circuit in the slave station 34 are not shown.

In this embodiment, it is assumed that the data communication device 238 is connectable to a maximum of 256 data terminal devices 401 and 411.

Transmission identification number generation circuit 1.1 a is transmission identification number 101
a as a parallel signal, and the reception identification number generation circuit 11b generates the reception identification number 101b as a parallel signal, and the transmission identification number 101m and the reception identification number 101b are used to generate data for a maximum of 256 units as described above. In order to assign a different identification number to each terminal device, the number is composed of an 8-bit binary number.

The transmission identification number 101a, which is this parallel signal, is input to the upper address as an address signal of the transmission read-only memory (ROM) 13a, and the lower and upper addresses of the ROM 13m are input from the transmission address counter 12a, which generates a time-series parallel signal. The parallel signal to be output is being input.

The ROM 13a stores the information stored in the corresponding address based on the parallel signal input to the address, that is, the random data 1 corresponding to each transmission identification number 1018.
Outputs 03a.

Random data 5103a and transmission data 104a are processed by an exclusive OR circuit (hereinafter referred to as EX-OR).

The random data 10 corresponding to each transmission identification number 101a described above is input as a logical operation input to the scrambler 148 configured with
3a and transmission data 104a, and after scrambling, a serial binary signal is output as transmission data 105a.

This transmission data 1058 is transmitted to the data communication device 2 of the master station 31.
The transmitted data is input to the port panel 21a in the wireless line 3a, and the transmitted data is converted to a preset communication channel and sent to the wireless line 3a.
03.

The transmitted data 105B reaches the data communication device 123b of the slave station 34 via the wireless line 303, and the received data 104B is sent to the port board 21b in this data communication device 23b.
is extracted as.

The received data 104b is the same as the aforementioned transmitted data 105 itself, and is output from the port board 21b in the data communication device 23b to the descrambler 14b.

On the other hand, the reception identification number generation circuit 1it) generates a reception identification number 101b, which is a parallel signal and is equal to the transmission identification number 101a described above, and outputs the reception identification number 101b to the reception address counter 13.
Also, counter b performs the same operation as the transmission address counter 12a described above, and generates a reception address signal 102b that is equal to the transmission address signal 102a.

And ROMI a b is also the above-mentioned ROMI 3a
The descrambler 14b stores random data 103b corresponding to each reception identification number 101b based on the input reception identification number 101b and the address specified by the reception address signal 102b.
Add to.

The descrambler 14b is composed of the same EX-OR circuit as the scrambler 148 described above, and
4b and the random data 103b corresponding to each reception identification number 101t) to calculate the exclusive OR of the received data 1.
05b and outputs this received data 105t) to the data terminal device 411.

It is clear that the received data 105b matches the transmitted data 1048.

In this way, by making the transmission identification number match the receiving m-separate number and performing communication, it is possible to restore and receive the same data as the transmission data.

In addition, a switch is provided in the sending occupational number generation circuit 11 so that the sending identification number can be changed depending on the desired communication destination, and this switch allows the sending identification number to be changed to the same sending identification number as the receiving identification number of the other party. It may also be configured to set.

In this way, in this embodiment, a master station, one or more relay stations, and one
When performing digital communication with the above-mentioned slave stations using a time division multiplexing/time division multiple access method, a transmission identification number generation circuit that generates a unique parallel transmission identification number corresponding to an identification number on the receiving side; a transmission address counter that outputs a transmission count signal in response to data;
a transmitting side storage device consisting of a ROM that uses the transmission identification number as an upper address signal and uses the transmission count signal as a lower address signal to output the dumb data stored at the address specified by the same address signal; The transmission system includes a scrambler that scrambles transmission data supplied from the terminal device based on random data output from the transmission side storage device and inputs the scrambled output to a port board in the data communication device. In addition, a receiving identification number generation means for generating a parallel receiving identification number unique to the receiving side, a receiving address counter that outputs a receiving count signal in response to received data, and a receiving identification number generating means for generating a parallel receiving identification number unique to the receiving side; A reception side storage device consisting of a ROM that is stored at the address specified by the signal and outputs the same random data as that stored in the transmission side storage device, and scrambled reception data output from the port board. The receiving system includes a descrambler that descrambles based on random data output from the receiving side storage device and outputs the descrambled output to the data terminal device.

[Effects of the Invention] As explained above, in the present invention, a unique value is given to each port board as a reception identification number, and when communicating, the transmission data is scrambled and transmitted according to the reception identification number of the communication partner. It is possible to provide a data communication system in which received data cannot be correctly restored by a terminal device other than the desired transmission destination, and data cannot be intercepted from a data terminal device other than the communication destination.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a secret device of a data communication system according to an embodiment of the present invention, and FIG. 2 is a diagram showing a connection state of a multidirectional multiplex wireless data communication system in a time division multiplexing/time division multiple access system. , FIG. 3 is a block diagram of the data communication device, and FIG. 4 is a diagram showing the communication format. 11a...Transmission identification number generation circuit, llb...Reception identification number generation circuit, 12m...Transmission address counter, 12b...Reception address counter, 13a, 13b...ROM, 14a...Scrambler , 14b...
・Descrambler.

Claims (2)

[Claims] (1) In a data communication system in which multiple data communication devices send and receive data via a common communication line, a pair of data communication devices encrypt the data transferred on the communication line and send and receive data to each other. A data communication system characterized by being equipped with a concealment means that allows data to be restored only between the parties. (2) In the data communication system according to claim 1,
The above-mentioned concealment means includes a storage means that stores an identification code unique to a pair of data communication devices that transmit and receive data, and a storage means that stores an identification code unique to a pair of data communication devices that transmit and receive data, and a storage means that stores the identification code unique to the pair of data communication devices that transmit and receive data, and a storage means that stores the same identification code when transmitting data to the communication line based on the identification code stored in the storage means. The device comprises: an encryption means for encrypting data; and a decryption means for decoding the data when receiving the data from the communication line based on the identification code stored in the storage means; A data communication system characterized in that a data communication device is configured to include the concealment means.