JPH0380752A - Information exchange transmission system - Google Patents

Abstract

PURPOSE:To eliminate the need of installing a cipher device in every terminal equipment by inserting the cipher device between a junction circuit trank and a junction circuit of each exchange, respectively, and enciphering the information transmitted between the terminal equipments by these cipher devices. CONSTITUTION:To the trunks to which each junction circuit 40 of an exchange is connected, a cipher device 50 is connected, respectively, information sent out of the exchange 30 is enciphered in accordance with a prescribed encipher algorithm and sent out to the junction circuit 40, and also, the information sent through the junction circuit 40 is decoded in accordance with a prescribed decoding algorithm and outputted to the exchange 30. In such a way, since the cipher device 50 is provided on every junction circuit trunk 32 of the exchange 30, the number of cipher devices to be installed in the system can be decreased remarkably, comparing with a conventional system in which the cipher device 50 is provided on every terminal equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an information exchange transmission system having a function of encrypting transmitted information.

(Prior art) In systems that exchange and transmit various data information such as call information and facsimile information, encryption devices are installed on the transmission path to protect the transmitted information from eavesdropping and information destruction. There is a device in which transmission information is encrypted using this encryption device.

FIG. 3 is a schematic configuration diagram showing an example thereof. In the figure, each terminal device 1 such as a telephone or a facsimile device is connected to an exchange 3 via a subscriber line 2, and this exchange 3 is connected to another exchange 3 to which a plurality of terminal devices 1 are similarly connected. They are mutually connected via a relay line 4. Further, each of the terminal devices 1 is provided with an encryption device 5. These encryption devices 5 encrypt the information sent from the terminal device 1 according to a predetermined encryption algorithm and output it to the subscriber line 2, and also encrypt the information received from the terminal device of the communication partner via the subscriber line 2. It is decoded according to a predetermined decoding algorithm and supplied to the terminal device 1. Furthermore, when using the cryptographic device 5 in this manner, the terminal device 1 is provided with a cryptographic operation control circuit. This control circuit supplies a gate signal to the encryption device 5 via the gate line 6 when the terminal device 1 sends out a connection signal that does not require encryption, such as a subscriber registration signal, and thereby encrypts the signal. Device 5
This is to stop the encryption operation of the connection signal so that the connection signal is not encrypted.

With a system having such a configuration, only communication information such as facsimile image information can be encrypted between the terminal devices 1, and this communication information can be transmitted in a confidential state.

(Problem to be solved by the invention) However, in such a conventional system, each terminal device 1
Since the encryption device 5 must be installed in each case, the system configuration becomes large-scale and expensive, and if the subscriber bears the installation cost of the encryption device 5, the financial burden on the subscriber increases. There was a point.

Therefore, the present invention focuses on the above-mentioned circumstances, eliminates the need to install an encryption device for each terminal device, thereby reducing the number of encryption devices installed, simplifying the system configuration and lowering the cost, and making it possible for subscribers to The purpose is to provide an information exchange transmission system that can reduce the burden.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention connects a plurality of exchanges each connected with a plurality of terminal devices via a trunk line, and connects these exchanges with each other via a trunk line. In an information exchange transmission system in which information is transmitted between the terminal devices via The information to be transmitted is encrypted, and transmission information identification means and encryption operation control means are provided corresponding to each of the above-mentioned encryption devices, and it is possible to determine whether the information sent from the terminal device is communication information or a connection signal. identify whether there is one by the above-mentioned identification means,
The cryptographic operation control means sets the corresponding cryptographic device to an active state when the transmitted information is identified as communication information by the identification means, and sets the cryptographic device to an inactive state when the transmitted information is identified as a connection signal. It is set to .

(Function) As a result, according to the present invention, an encryption device need only be provided for each trunk of the exchange, not for each terminal device, so that the number of encryption devices installed in the entire system can be reduced. This makes it possible to simplify the system configuration and reduce the cost. Furthermore, since each subscriber does not have to bear the cost of installing an encryption device, the financial burden on the subscriber can also be reduced.

(Embodiment) FIG. 3 shows the configuration of an information exchange transmission system in an embodiment of the present invention. In the same figure, switch 3
An encryption device 50 is connected to each trunk to which each trunk line 40 of No. 0 is connected. These cryptographic devices 50
When the information sent from the exchange 30 is encrypted according to a predetermined encryption algorithm and sent to the relay line 40, the information sent via the relay line 40 is decoded according to a predetermined decryption algorithm and sent to the exchange 30. Note that each terminal device 10 is directly connected to the exchange 30 via a respective joining line 20.

By the way, as shown in FIG.
A plurality of subscriber circuits 31 provided for each relay line 40, a plurality of trunks 32 provided for each trunk line 40, and a communication path for selectively connecting these subscriber circuits 31 and trunks 32. switch 33, and each subscriber line 2o
It has a first signal circuit 34 for transmitting and receiving various connection signals to and from the relay line 40, a second signal circuit 36 for transmitting and receiving various connection signals to and from the relay line 40, and a control circuit 35. The control circuit 35 mainly performs switching control of the communication path switch 33, etc., and this switching control is performed in response to a connection signal sent from the terminal device 1o or the relay line 40 side.

Further, the exchange 30 is provided with a gate signal generation circuit 37. This gate signal generation circuit 37 is connected to the signal circuit 3
6 to the trunk 32, a gate signal GS of, for example, "L" level is generated, and this gate signal GS is supplied to the corresponding encryption device 50 to stop the encryption operation of the encryption device 50. It is something that makes you

With such a configuration, suppose now that the terminal device 10 sends out a connection signal such as a subscriber registration signal. This connection signal is then introduced to the exchange 30 via the subscriber line 20 and detected by the first signal circuit 34. This connection signal is transferred from the first signal circuit 34 to the second signal circuit 36 via the control circuit 35, and is sent from the second signal circuit 36 to the trunk line 40 via the trunk 32. By the way, at this time, the gate signal generation circuit 37 outputs a gate signal GS having a length corresponding to the transmission period of the connection signal, as shown in FIG.
0. Then, the encryption device 50 becomes inactive only during the period when the gate signal GS is at the “L” level, so that the connection signal passes through the encryption device 50 without being encrypted and is sent to the trunk line 40 as it is. .

Therefore, the problem that unnecessary encryption is performed on the connection signal does not occur.

On the other hand, when the terminal device 10 sends a message such as facsimile image information, this message is sent from the subscriber circuit 31 in the exchange 30 to the trunk line 40 via the call path switch 33 and the trunk 32. . That is, no connection signal is output from the signal circuit 36 during the transmission period of the message.

Therefore, the gate signal GS from the gate signal generation circuit 37
is not generated, and as a result, the encryption device 50 enters the encryption operation state as shown in FIG. Therefore, the above-mentioned message is sent to the relay line 40 after being subjected to a predetermined encryption process in the encryption device 50. Therefore, there is no worry that the above-mentioned message will be viewed and viewed by eavesdropping while being transmitted on the relay line 40. do not have.

As described above, in this embodiment, the encryption device 50 is
Since the encryption device 50 is provided for each trunk 32 for a trunk line, the number of encryption devices installed in the system can be significantly reduced compared to a conventional system in which an encryption device 50 is provided for each terminal device.

Therefore, the system configuration can be simplified and the cost can be reduced. Furthermore, since there is no need to attach an encryption device to the terminal device, the subscriber does not have to bear the cost of installing the encryption device, thereby reducing the financial burden on the subscriber.

Furthermore, a gate signal generation circuit 37 is provided in the exchange 50,
Since the operation of the cryptographic device is controlled, the cryptographic device 50 does not encrypt connection signals such as subscriber registration signals, but can encrypt and transmit only messages.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, a case was explained in which a message such as facsimile image information was transmitted between terminal devices.
The same method can be applied to telephone signals, computer data, and the like. Further, in the above embodiment, the encryption device 50 is installed outside the exchange 30 and the gate signal generation circuit 37 is installed inside the exchange 30, but the encryption device 50 may be installed inside the exchange 30, and the gate signal generation circuit 37 is installed inside the exchange 30. The circuit 37 may be installed outside the exchange. Furthermore, the control circuit 35 of the exchange may have the function of a gate signal generation circuit. In addition, the configuration of the means for identifying communication information and connection signals, the configuration and control procedure of the means for controlling the operation of the cryptographic device, the configuration and type of the information exchange transmission system, the configuration of the cryptographic device and the encryption method etc., can be implemented with various modifications without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, an encryption device is inserted between the trunk line of each of the exchanges and the relay line, and data is transferred between terminal devices using these encryption devices. information transmitted from the terminal device is encrypted, and transmission information identification means and encryption operation control means are provided corresponding to each of the above-mentioned encryption devices, and whether the information sent from the terminal device is communication information or a connection signal. If the transmitted information is identified as communication information by the identifying means, the corresponding cryptographic device is set to an operating state, and the cryptographic operation control means sets the corresponding cryptographic device to an operating state when the transmitted information is identified as communication information by the identifying means. In some cases, by setting the encryption device to a non-operating state, it is possible to eliminate the need to install an encryption device for each terminal device, thereby reducing the number of encryption devices installed and simplifying the system configuration. Accordingly, it is possible to provide an information exchange transmission system that can reduce the burden on subscribers, and reduce the cost.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing the main configuration of an information exchange and transmission system according to an embodiment of the present invention, FIG. 2 is a timing diagram used to explain the operation of the system, and FIG. 3 is the overall configuration of the system. FIG. 4 is a schematic diagram of a conventional information exchange transmission system. 10... Terminal device, 20... Joining line, 30...
exchange, 31... subscriber circuit, 32... trunk,
33... Communication path switch, 34... First signal circuit, 35... Control circuit, 36... Second signal circuit, 37... Gate signal generation circuit, 40... Relay line ,
50... Encryption device, GS... Gate signal.

Claims (1)

[Scope of Claims] An information exchange and transmission system in which a plurality of exchanges each connected to a plurality of terminal devices are connected via a communication line, and information is transmitted between the terminal devices via these exchanges, a plurality of encryption devices each inserted between the communication line trunk of each of the exchanges and the communication line for encrypting information transmitted between the terminal devices; and a plurality of encryption devices provided corresponding to the encryption devices. , an identification means for identifying whether the signal sent from the terminal device is communication information or a connection signal; and when the identification means identifies the transmission information as communication information, the encryption device is put into an operating state. 1. An information exchange and transmission system comprising: an encryption operation control means for setting an encryption device to a non-operating state when the encryption device is set to a connection signal and is identified as a connection signal.