JPH04185137A - Cryptographic device - Google Patents

Abstract

PURPOSE:To attain cryptographic communication between facsimile equipments of different device kinds by providing a format discrimination meant and a format conversion means converting a signal format into a signal format of a special criterion when the result of discrimination of the means represents a signal format other than the signal format of the special criterion to the cryptographic device. CONSTITUTION:A digital identification signal (DIS) including a unique communication protocol request sent from a receiver side facsimile equipment 20 is fetched by a CPU 47 via a facsimile side interface 41b, an NCU 41 and a MO DEM 42. Succeedingly the CPU 47 uses a format discrimination means 47a to check the signal format of the DIS. As a result, when the format of the DIS is not a signal format by the CCITT recommendations, a format conversion means 47b uses to delete the unique signal format defined freely by the user and the signal format of the CCITT recommendations is newly generated. Thus, the cryptographic communication between the existing facsimile equipments of every manufacture is attained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is used in facsimile communication, etc., and is provided between a terminal device and an exchange, and encrypts data to be transmitted to maintain the confidentiality of communication. This relates to a conversion device.

(Prior Art) In recent years, as the value of information has increased, there has been a growing demand for confidentiality of communications not only in the political field such as diplomacy, but also in the business community.

Conventionally, as technology in this type of field, the Mitsubishi Electric catalog "Facsimile NELFAS980/970/960
There was something written in J.

In the facsimile machine as shown in the above document,
It has a built-in encryption device that has an encryption communication function that can encrypt and transmit image signals when a high degree of confidentiality is required for communication.

(Problems to be Solved by the Invention) However, the above encryption device has the following problems.

CCIT as a standard communication protocol for facsimile machines
T (International Telegraph and Telephone Advisory Committee) Recommendation T.

However, in order to maintain their own superiority, facsimile manufacturers communicate with their own facsimile machines of the same model using a proprietary communication protocol whose transmission speed, bit definition, etc. are not made public.

The above-mentioned encryption device is installed in the same type of facsimile machine on both the sending and receiving sides, and even if the communication protocol is a proprietary communication protocol that is not disclosed, encrypted communication is possible because the communication protocols are the same. However, there is a problem in that encrypted communication is not possible between different types of facsimile machines because their communication protocols are different.

The present invention provides an encryption device that solves the problem E of the prior art in that encrypted communication is not possible between different types of terminal devices due to different communication protocols.

(Means for Solving the Problems) In order to solve the above problems, the present invention is provided in a communication system that transmits data between a sending terminal device and a receiving terminal device via an exchange, An encryption device that performs predetermined encryption processing on data takes the following measures.

inputting a digital identification signal including a communication protocol to be output from the receiving terminal device to the transmitting terminal device;
a format determining means for determining whether or not the signal format of the digital identification signal is a signal format of a specific standard; and a format conversion means for converting the format into the signal format of the specific standard.

(Operation) Since the present invention has the encryption device configured as described above, the format determination means inputs a digital identification signal including a communication protocol, and determines that the signal format of the digital identification signal is a signal format of a specific standard. Determine whether or not. When the determination result of the format determining means is a unique signal format other than the signal format of the specific standard, the format conversion means converts the signal format into the signal format of the specific standard, and converts the unique communication protocol into the specific standard signal format. communication protocol (.This allows for communication between different types of terminal devices.
Since the communication protocol is unified to a specific standard communication protocol, encrypted communication becomes possible. Therefore, the above problem can be solved.

(Embodiment) FIG. 1 is a block diagram of a configuration of an encryption device showing an embodiment of the present invention, and FIG. 2 is a diagram of a communication system of a facsimile machine.

In FIG. 2, this communication system includes facsimile machines 10.20 of different models, and the facsimile machine 1
An exchange 30 for line connection is installed between 0.20 and 20.00. And the exchange 8! 30 and facsimile machine 10
An encryption device 40 is connected between the exchange 30 and the facsimile machine 20.

In FIG. 1, this encryption device 40 is connected to a communication line (regular interface 41a, a line switching NCU (Net) connected to a facsimile side interface 41b).
work ControlUnit, network control device) 4
1, and a modem 42 having an analog/'digital conversion function is connected to the input side of the Net '41. Further, on the output side of the modem 42, a data buffer 43 for data driving, an encryption LSI 44 for encrypting data output from the data buffer 43, and an encryption LSI 4 are provided.
a buffer 45 for driving data encrypted by 4;
and a modem 46 having a digital/analog conversion function are sequentially connected. The output side of the modem 46 is connected to the output side of the NCU 41.

On the other hand, the modem 42 is connected to a CPU that controls the operation of the entire device.
(Central processing unit) 47, stores control programs and data, etc. RAM (random access, memory) and ROM
It is commonly connected to a memory section 48 (read-only memory) and a modem 46.

Further, the CPU 47 includes a format determining means 47a and a format converting means 47b. The format determination unit 47a receives a digital identification signal including a communication protocol that is output from a receiving terminal device, such as the facsimile device 20, to a transmitting terminal device, such as the facsimile device 10.
ati.

n Signal (hereinafter referred to as DIS),
The format conversion means 47b has a function of determining whether or not the signal format of this DIS is a signal format of the CCITT recommendation (specific standard), and the format conversion means 47b converts the signal format into a signal format other than the signal format of the CCITT recommendation if the judgment result of the format judgment means 47a is a signal format other than the signal format of the CCITT recommendation. format, it has a function of converting the signal format to the signal format recommended by CCITT. Here, DIS is a signal that informs the transmitting facsimile machine 10 of the capabilities (communication speed, unique communication protocol, etc.) of the receiving facsimile machine 20.

FIG. 3 is a signal sequence diagram for CCITT Recommendation T.30. The operation of the encryption device 40 will be explained with reference to this figure.

The dial pulse emitted from the sending facsimile machine 10 is transmitted to the receiving facsimile machine! 20, the receiving facsimile machine 20 activates the auto-answer function and enters an off-hook state. Furthermore, a link back tone is sent to the sending facsimile device 10, and then a DIS is sent to inform the sending facsimile device 10 of its own capabilities such as transmission speed and unique communication protocol.

The receiving side encryption device 40 is the receiving side facsimile device 20
DI containing a unique communication protocol request sent by
S, facsimile side interface 41b, NCU4
1. Receive via modem 42 and import into CPU 47.

Subsequently, the CPU 47 uses the format determining means 47a to check the signal format of the DIS. As a result, if the DIS is not in the CCITT standard signal format, the format conversion means 47b is used to convert the DIS to an original signal format (N
SF, C5I, etc.) and generate a new CCITT standard signal format.

The DIS converted into the CCITT standard signal format in this way is sent to the exchange 30 via the modem 46, NCU 41, and line-side interface 41a. Further, this DIS is sent to the sending side cryptographic device 4 via the exchange 30.
0 and is sent to the sending facsimile machine 10. The sending facsimile device 10 receives the CCITT standard DIS, and uses a digital command signal (DC8) to inform the receiving facsimile device 20 that it will thereafter transmit using the CCITT standard protocol. From now on, communications will be made public to CCI.
It is executed using the TT standard protocol.

First, a training TCF signal (Traini) is sent from the sending facsimile machine 10 to the receiving facsimile machine 20.
ng Check, Training Check) is sent, and in response, the receiving facsimile machine 20 sends a CFR (Configuration to R).
When a signal (eceive, reception preparation confirmation) is sent, it means that the pre-communication procedure has been completed, so the sending facsimile machine 10 reads the original to be sent and starts the sequence to send the image data that is its contents. will transition.

When image data is sent from the sending facsimile device 10 to the receiving facsimile device 20, the image data is compressed using a predetermined compression method. The image data compression method is CCI.
The MH method (Modified
Huffman c.

de, -dimensional encoding method) and MR method (Modify
d Read code, two-dimensional encoding method). Image data is sent to the receiving facsimile device 20 using these methods.

The image data sent from the sending facsimile device 10 is input to the encryption LSI 44 via the facsimile interface 41b, N(, U41, modem 42, and buffer 43) of the sending encryption device 40. Then, in the encryption LSI 44, the 58th bit of the input image data is transposed to the 1st bit, the 50th bit to the 2nd bit, etc., and the image data is encrypted.

Thereafter, the encrypted image data is transferred to the buffer 4, the modem 46, the NCU 41 . and line interface 41a
The data is sent to the exchange 30 via the network.

Then, it is sent to the receiving side encryption device 40 via the exchange 30, and the line interface 4: La, NCU 41,
The signal is input to the encryption LSI 44 via the modem 42 and buffer 43. The image data inputted to the encrypted LSI 44 is decoded after being transposed in the opposite manner to the transposition performed in the above encryption process, and then sent to the buffer 45, the motif 46, and the NCU 4.
1. It is sent to the receiving facsimile machine 20 via the line interface 41a. This decoded image data is printed in plain text by the facsimile machine 20 on the receiving side.

As described above, when the image data for the second page continues after the first image data is printed, the multi-page signal (MPS> is sent from the sending facsimile machine 10 to the receiving facsimile machine 20. On the other hand, the receiving facsimile machine 20 uses MCF (Message C
onfirm-ation, message confirmation). Then, the image data for the second page is sent out in the same way as the first page, and after the sending of all the image data is completed, the sending facsimile machine 10 sends an EPO signal (End of
Procedure, procedure completed) is sent. Then, in the receiving facsimile machine 20, the MCF (
Message Confi rmation on
.

Send a message (confirm message). Further, in the sending facsimile device 10, a DCN (DiscOnnec)
t, a line disconnection command), the communication line is disconnected and the facsimile communication is terminated.

This embodiment has the following advantages.

The encryption device 40 is attached externally to the facsimile machine, and the unique communication protocols of each company's facsimile machines are converted to the CCITT standard within the encryption device 40, so that the encryption device 40 can be used without modifying the existing facsimile machines of each company. This enables encrypted communication between facsimile machines of different companies to maintain the confidentiality of communication.

Note that the present invention is not limited to the illustrated embodiment, and various modifications are possible. For example, there are the following variations.

(I> In the above embodiment, the facsimile machine TO, 20 is used as the transmitting terminal device and the receiving terminal device to perform facsimile communication, but the present invention is not limited to this, and can also be applied to personal computer communication, etc.) can.

(II) Encryption LSI 44 for encryption processing and decryption processing
Although this is described above, it may also be performed by program processing of the CPU. This reduces the circuit formation area.

(III> For example, the image data may be configured not to be input to the encryption LSI 44, and the encryption device 40 may be provided with a mode in which the image data is not encrypted.

(1v) In the above embodiment, the encryption device 40 is configured to be externally attached to the facsimile machine 210.20, but it may also be configured to be built-in.

(V) In the above embodiment, the CCITT recommendation was used as the specific standard, but it is not limited to this as long as it complies with the spirit of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, a digital identification signal outputted from a receiving terminal device to a transmitting terminal device is input, and the signal format of the digital identification signal conforms to a specific standard. It is determined whether the signal format is the same or not, and if the determination result is a signal format other than the signal format of the specified standard, the signal format is converted to the signal format of the specified standard, so that each company's terminal The unique communication protocol of the device, e.g.
It can be converted to the CITT standard, enabling encrypted communication between existing facsimile machines of various companies to maintain the confidentiality of communication.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the configuration of an encryption device showing an embodiment of the present invention, FIG. 2 is a diagram of the communication system of a facsimile machine, and FIG. 3 is a signal sequence diagram based on CCITT Recommendation T.30. 10... Sending side facsimile machine, 20...
... Receiving side facsimile machine, 30 ... Switching machine, 40 ... Encryption device, 47 a ...
Format determination means, 47b...Format conversion means.

Claims (1)

[Scope of Claims] An encryption device that is provided in a communication system that transmits data between a sending terminal device and a receiving terminal device via an exchange, and that performs predetermined encryption processing on the data. , inputting a digital identification signal including a communication protocol to be output from the receiving terminal device to the transmitting terminal device;
a format determining means for determining whether or not the signal format of the digital identification signal is a signal format of a specific standard; An encryption device comprising: format conversion means for converting a format into a signal format according to the specific standard.