JPH08321955A - Facsimile communication method - Google Patents

Abstract

PURPOSE: To allow surely a receiver side to receive data in ciphering communication by ciphering a head part, sending the ciphered part and allowing a transmitter side to discriminate whether or not the ciphered head part can be accurately decoded by the receiver side on the signal returned from the receiver side. CONSTITUTION: When a transmitter side discriminates it that whether or not a receiver side has the same manufacturer's model and a ciphering communication function in steps #101-107, an image of a head is ciphered and the ciphered part is sent in the step #108 by a transmitter side. The receiver side converts the ciphered image of the head part into a plain sentence. When ciphering keys are coincident with each other, the ciphered sentence is correctly converted into the plain sentence so as to be decoded. When the ciphering key is coincident, the receiver side returns a CFR signal representing the receptible state in the step #107. When not coincident, a FTT signal in the step #114 is returned and a transmitter side sends a DCN signal in the step #113 to interrupt the line. When the CFR signal is returned, since the ciphering key is coincident, the remaining ciphered image is sent to the receiver side in the step #110.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile communication method, and more particularly to a facsimile communication method having a cryptographic communication function.

[0002]

2. Description of the Related Art In recent years, in facsimile communication using a telephone line, a function of performing encrypted communication has been attracting attention. Such a function is a so-called "G3 facsimile" defined by CCITT (International Communication Advisory Committee).
This is a function that has come to be adopted in the standard, and it is an effective function only when both the transmitting side and the receiving side are unified by the same manufacturer and both have an encryption communication function. This is called "in-house non-standard communication".

The structure of a facsimile apparatus having the function of performing such non-standard communication between companies is generally represented by a block diagram as shown in FIG. In the figure, reference numeral 1 is a control unit composed of a microcomputer or the like, and controls the entire control.

As shown in FIG. 5, the control unit 1 includes a central processing unit (hereinafter abbreviated as "CPU") 2, a program read-only storage element (hereinafter abbreviated as "ROM") 3, and a random access memory. (Hereinafter abbreviated as “RAM”) 4. Further, the RAM 4 is used as a work area as one form of a storage area, a storage area for the encryption key K, and the like, as shown in FIG.

Returning to FIG. 4, reference numeral 5 denotes an operation unit having a key array operated by the user. Reference numeral 6 denotes an encoding / decoding circuit, which is a circuit for performing compression / expansion of communication image data. Reference numeral 7 denotes an encryption / plain culture circuit, which performs encryption when the facsimile communication device operates as a transmitting side and performs plain culture when it operates as a receiving side. 8
Is a modem unit, 9 is an NCU (network control unit), and 10 is a telephone line.

FIG. 7 shows a procedure of general cryptographic communication. In the figure, 91 to 93 are signal processing procedures on the transmission side, and 91 encodes image data. Then, in order to make it a secret communication, at 92, it is encrypted with the key and
Send at 3.

Signals 94 to 96 are signal processing procedures on the receiving side, and the encrypted received data received at 94 is flattened at 95. This plain culture is to decrypt the ciphertext using the same key as the sender. The plain-text data is decrypted at 96 to become the original image data. The key here is a kind of data.

A reading unit 11 has a scanner 11a for reading a document. An image processing unit 12 performs processing such as shading correction on the read image data.
Reference numeral 13 is a transmission function unit, 14 is a reception function unit, and 15 is a recording unit having a printing unit 15a and the like. The operation unit 5 described above,
The modem unit 8, the NCU 9, the scanner 11a, the printing unit 15a and the CPU 2 are connected via a data bus 17, as shown in FIG.

Now, FIG. 6 is an explanatory diagram showing a communication procedure of a conventional example in the facsimile apparatus of the present invention. The communication operation of the conventional facsimile apparatus configured as described above will be described with reference to FIG. It should be noted that FIG. 6A shows normal encrypted communication, and FIG. 6B shows the case where the receiving side does not have the encrypted communication function even in the other company's machine or the own machine. Also,
All signal name abbreviations used in the following description are CC
ITT Recommendation T. It is defined by 30.

First, in step # 501, on the transmitting side, dialing is carried out as a normal telephone operation by operating the keys on the operating section 5, and a calling instruction is sent to the modem 8 to send a predetermined pulse from the NCU 9 to the telephone line 10. To send a call to the receiving side and connect the line. After this, step # 5
In 02, a single tone CNG (calling tone) signal is transmitted, and in response thereto, a single tone CED (callee identification) signal is transmitted from the receiving side in step # 503. As a result, it is confirmed that the facsimile machines have communicated with each other and the line has been connected.

Next to this, from the receiving side, step # 5.
At 04, low-speed signals indicating reception capability such as NSF (non-standard function) signal, CSI (callee identification) signal and DIS (digital identification) signal are returned. here,
The NSF signal is an optional signal including information for performing non-standard communication, and informs the transmitting side that, for example, confidential communication is possible or relay instruction communication is possible. The CSI signal is an optional signal indicating the telephone number of the called terminal. Further, the DIS signal is a signal for notifying the transmitting side of the receiving capability of the called terminal, for example, the receivable recording size and the communication speed.

On the transmitting side, each bit of these NSF signal, CSI signal and DIS signal is inspected, and only in the case of its own machine and the cipher receiving function, the low speed TSI (transmitting terminal identification) signal and NSS ( A non-standard function setting) signal is sent, a bit for encrypted communication is set in the information field of the NSS signal, and encrypted communication is set. In other cases, as shown in FIG. 5B, the process jumps to step # 511, transmits a DCN (disconnect command) signal to the receiving side, disconnects the line, and ends all processing.

After that, in step # 506, the transmitting side sends a TCF (training check) signal of all 0s at high speed for 1.5 seconds to the receiving side to check the receiving ability.
The TCF signal is a signal sent from the transmission side to the reception side, and is a signal for confirming whether or not the image data is normally sent at the same transfer speed as the image transmission before the image transmission. "0" for 1.5 seconds at a transfer rate of 14400-2400bps (21600 "for 14400bps)
0 "), and the receiving side inspects the TCF signal,
Whether or not it was received correctly, that is, all received data is "
Check if it was 0 ”. If the line condition is bad and there is a lot of noise, the value of“ 0 ”for 1.5 seconds will be garbled and will change to“ 1 ”.
It can be judged that reception is impossible.

The receiving side returns a CFR (reception preparation confirmation) signal if reception is possible, and an FTT (training failure) signal if reception is not possible. When the FTT signal is sent, the sending side returns the processing to step # 505,
After reducing the transmission speed, the TSI signal, NSS signal and TCF signal are transmitted again. These repeating processes are performed until the CFR signal is returned from the receiving side as in step # 507. Such an operation is called "fallback".

From the receiving side, as in step # 507, C
When the FR signal is returned, in step # 508 the transmitting side transmits the image encrypted by the encryption circuit 7 using the predetermined encryption key (16-digit numerical value) to the receiving side,
When all the originals have been transmitted, an EOP (procedure end) signal is sent to the receiving side in step # 509. In response to this, the receiving side returns an MCF (message confirmation) signal in step # 510. After this, on the sending side,
In step # 511, the DCN signal is sent, the line is disconnected, and the communication is ended.

As described above, in the conventional facsimile apparatus, the information field of the NSF signal issued by the receiving side is provided with a bit indicating whether or not there is an encrypted communication function to inform the transmitting side, and whether or not the transmitting side performs the encrypted communication. Has been provided in the information field of the NSS signal to notify the receiving side, and it has been decided whether or not to carry out encrypted communication. Note that these communication procedures are also used for non-standard communication only between own machines, such as confidential transmission and relay instruction transmission.

[0017]

However, in the conventional facsimile apparatus as described above, even if the plaintext cannot be accurately obtained without knowing the encryption key, the encryption can be performed only if the encryption reception function is available. There is a problem that image data is received.

For the receiving side who does not know the encryption key, even if the image data with the encryption key is received, it is completely useless, and from the transmission side's point of view, the image data is sent to the wrong party even if it is encrypted. Is dangerous. In order to prevent such a problem, it is necessary to confirm whether or not the other device has the same encryption key, but there is a problem that the other device cannot be notified of the encryption key in the above communication procedure. is there. This is because there is no point in encrypted communication by notifying even the person who does not know the encryption key.

The present invention has been made in view of the above problems, and it is possible to confirm whether or not the other device has the same encryption key without notifying the other device of the encryption key, and to obtain the same encryption key. An object of the present invention is to provide a facsimile device that performs more secure encrypted communication by performing communication only when there is a communication.

[0020]

In order to achieve the above object, in the facsimile communication method of the present invention, in claim 1, the entire image is encrypted and transmitted in the facsimile communication method having a function of performing encrypted communication. The sending side sends the sending part by encrypting the head part before sending and judging whether the receiving side can correctly decipher the encrypted head part based on the signal returned from the receiving side. The determination step of determining whether or not the same side has the same encryption key, and when it is determined that the same encryption key is possessed in this determination step, the above image is encrypted and transmitted, and when it is determined that it does not have the same, the communication ends. And a control step for

According to a second aspect of the present invention, in the facsimile communication method having the function of performing encrypted communication, the information field of the signal of the pre-communication procedure sent from the transmitting side to the receiving side contains the legitimate information and the encrypted information. A generation stage that creates
Put this encrypted information on the procedure signal and send it to the receiving side,
A determination step of determining whether or not the result decrypted on the receiving side matches the above-mentioned legitimate information based on a signal returned from the receiving side, thereby determining whether or not they have the same encryption key; The determination step of the determination step includes a control step of encrypting and transmitting the image when it is determined that they have the same encryption key and ending the communication when it is determined that they do not have the same encryption key.

[0022]

With the above construction, in the facsimile communication method having the function of performing the encrypted communication, the first portion is encrypted and transmitted before the entire image is encrypted and transmitted in the transmitting step, and in the determining step. By determining whether or not the receiving side can accurately decipher the encrypted head portion based on the signal returned from the receiving side, it is determined whether or not the receiving side has the same encryption key as the transmitting side, In the control step, if it is determined in the determination step that the same encryption key is possessed, the above image is encrypted and transmitted, and if it is determined that it is not possessed, the communication is ended, so that even in the case of encrypted communication, the receiving side is sure to It will be received.

According to a second aspect of the present invention, in the facsimile communication method having the function of performing encrypted communication, the legitimate information is encrypted in the information field of the signal of the pre-communication procedure sent from the transmitting side to the receiving side at the generation stage. Make information that
Put this encrypted information on the procedure signal and send it to the receiving side,
By determining based on the signal returned from the receiving side whether or not the decrypted result on the receiving side matches the above-mentioned regular information, it is determined in the determining stage whether or not the same encryption key is possessed. If the determination result of the determination step is that the image has the same encryption key, the image is encrypted and transmitted, and if it is determined that the same key is not used, the communication is ended in the control step. It will be received by the receiving side.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A facsimile communication apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a communication procedure of a facsimile communication method according to the first embodiment of the present invention. The hardware configuration is shown in FIG. 4 and FIG.
Since it is the same as the block diagram of the general facsimile apparatus shown in FIG.

The operation of this embodiment will be described with reference to FIG. First, steps # 101 to # 107 are the same as steps # 501 to # 507 in the conventional example, and thus the description thereof will be omitted. When the receiving side does not have the cryptographic communication function even in the other company's machine or in the company's machine, it jumps to step # 113 and transmits the DCN signal as shown in (b) of FIG.

When it is determined in steps # 101 to 107 that the receiving side has its own machine and has an encryption communication function,
In step # 108, the transmitting side encrypts and sends the image of the head portion. In addition, as the beginning part, HD
It may be the first one frame when converted to an LC (high-level transmission control procedure) frame, or may be several frames. Further, it may be the first one line when the transmission image is read, or several lines. Here, the data structure of NSS is shown in FIG. It has a form in which an error correction code is added to normal data.

On the receiving side, the encrypted image at the head is plain-cultured, and if the encryption keys match as described with reference to FIG. 6 of the prior art, it is correctly plain-cultured and decrypted. This operation will be described in more detail.

The image data is represented by digital data of "1" and "0", and when the image data includes, for example, five 0 (white), it is represented by a code such as "01". (Coding). 1 (black) is represented by the same predetermined rule. When this code "01" is encrypted with a key and is plain-cultured with the key prepared on the receiving side,
When the key is correct, "01" is output by the encryption / plain culture circuit 7 of FIG. 4, "and further decoding of it yields image data of 00000. However, when the keys do not match, "01" is output as plain culture output.
Instead, "00" is obtained. This "00" is 0
If it is a code indicating that three are consecutive, the number of bits will be different from the actual number.

According to such a principle, when the plain culture is performed for one line, for example, when the facsimile mode is the fine mode, the image data is 17 lines per line.
If it is 28 bits, it means that the encryption keys match, but if it is 1728 bits, it means that the encryption keys do not match.

If the encryption keys match, the receiving side returns a CFR signal indicating that the data can be received in step # 107, and if they do not match, the receiving side returns step # 7 as shown in FIG. It jumps to 114 and returns the FTT signal, whereby the transmitting side returns to step # 113 to transmit the DCN signal and disconnect the line.

Now, returning to FIG. 1 (a), when the CFR signal is returned, the encryption keys match, so
In step # 110, the remaining encrypted image is transmitted to the receiving side. Subsequent processing steps # 111 to # 11
Since No. 3 is the same as # 509 to # 511 in the conventional example, the description thereof is omitted.

As described above, according to this embodiment, the head encrypted image encrypted in step # 108 is sent to the receiving side, and whether or not the same key is possessed is determined in step # 109 depending on whether or not the CFR signal is sent back. Since it is checked, the receiving side will not receive unnecessary data that is encrypted and cannot be decrypted, and the transmitting side will not perform encrypted communication to the wrong party, so the effect of improving safety There is. Further, there is an effect that it is possible to prevent that the message is sent to the wrong partner and is not sent to the intended partner.

FIG. 2 is a diagram showing a transmission procedure of the facsimile communication method according to the second embodiment of the present invention. The hardware configuration is the same as that of the conventional example, and a description thereof will be omitted. FIG. 2A is a diagram showing a communication procedure in normal encrypted communication. In the figure, step # 201
# 204 is steps # 501 to # 50 in the conventional example.
The same as No. 4 and its explanation is omitted. If the receiving side does not have a cryptographic communication function even if it is a device of another company or its own device,
As shown in FIG. 2B, the DCN is jumped to step # 211.
It sends a signal and ends.

Now, in step # 205, the NSS
As shown in (b) of FIG. 3, the normal information and the data obtained by encrypting the normal information are inserted into the frame of the NSS signal and transmitted to the receiving side. Here, the NSS signal is a signal including information for performing non-standard communication and is an optional signal. It is a response to the NSF signal, and is a signal for comparing the capability of the receiving side indicated by the NSF signal with the capability of the transmitting side to determine the transmission parameter and notifying the receiving side.

Subsequently, in step # 206, T
The CF signal is transmitted from the transmitting side. Since this signal is a high-speed signal and is sent at a short interval of 75 ms ± 20 ms from the transmission of the NSS signal, it can be considered as a signal that is a set with the NSS signal.

The encrypted information is encrypted / plain culture circuit 7
At the receiving side, it is deciphered by a predetermined key and compared with legitimate information at the receiving side. If they are the same, it is determined that they have the same encryption key, and communication is continued. On the contrary, if no match is found, the process jumps to step # 212 as shown in FIG. 2C, and the receiving side transmits the DCN signal to the transmitting side.

On the contrary, if a match is found, a CFR signal is returned in step # 207, and then an encrypted image is transmitted in step # 208. Subsequent processing steps # 209 to # 211 are the same as steps # 509 to # 511 in the conventional example, and detailed description thereof will be omitted.

As described above, according to the present embodiment, the information to be put on the NSS signal in step # 205 is sent to the receiving side by transmitting the encrypted information, and it is checked whether or not the same information is obtained. Because
The receiving side does not receive unnecessary data that has been encrypted and cannot be decrypted, and the transmitting side does not perform encrypted communication to the wrong party, which has the effect of increasing security. Also, I sent it to the wrong person,
The effect is that it can be prevented from not sending to the intended recipient.

In the above embodiment, in claim 1, the transmission step corresponds to step # 108, the determination step corresponds to step # 109 and step # 114, and the control step corresponds to step # 110 and step # 110. 113 corresponds. Further, in claim 2, the generation step is step # 205.
Corresponds to, the determination step corresponds to step # 207, and the control step corresponds to step # 208 and step # 212.

[0040]

As described above, according to the facsimile communication method of the present invention, in claim 1, in the facsimile communication method having the function of performing encrypted communication, the head portion is encrypted before the entire image is encrypted at the transmission stage and transmitted. Encrypted and sent,
Whether or not the receiving side has the same encryption key as that of the transmitting side can be determined by determining whether or not the receiving side can accurately decrypt the above-mentioned encrypted head portion in the determination step based on the signal returned from the receiving side. In the control step, if it is determined in the control step that the same encryption key is possessed, the above-mentioned image is encrypted and transmitted, and if it is determined that it is not possessed, the communication is ended, so even if it is encrypted communication This has the effect of being received by the receiving side.

Therefore, the receiving side does not receive unnecessary data that has been encrypted and cannot be decrypted, and the transmitting side does not perform encrypted communication with the wrong party, which has the effect of increasing security. is there. Further, there is an effect that it is possible to prevent that the message is sent to the wrong partner and is not sent to the intended partner.

According to a second aspect of the present invention, in the facsimile communication method having the function of performing encrypted communication, the legitimate information is encrypted in the information field of the signal of the pre-communication procedure sent from the transmitting side to the receiving side at the generation stage. Make information that
Put this encrypted information on the procedure signal and send it to the receiving side,
By determining based on the signal returned from the receiving side whether or not the decrypted result on the receiving side matches the above-mentioned regular information, it is determined in the determining stage whether or not the same encryption key is possessed. If the determination result of the determination step is that the image has the same encryption key, the image is encrypted and transmitted, and if it is determined that the same key is not used, the communication is ended in the control step. This has the effect of being received by the receiving side.

Therefore, the receiving side does not receive unnecessary data that has been encrypted and cannot be decrypted, and the transmitting side does not perform encrypted communication with the wrong party, which has the effect of increasing security. is there. Further, there is an effect that it is possible to prevent that the message is sent to the wrong partner and is not sent to the intended partner.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a communication procedure in a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a communication procedure in the second embodiment of the present invention.

FIG. 3 is a diagram showing a structure of a frame in the embodiment.

FIG. 4 is a schematic block diagram showing a general configuration of a facsimile device.

FIG. 5 is a block diagram showing a specific configuration of a control unit and other peripheral components.

FIG. 6 is an explanatory diagram showing a communication procedure in a conventional example of the present invention.

FIG. 7 is a diagram showing a general operation procedure of each of a transmission side and a reception side in encrypted communication.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 control part 5 operation part 6 encoding / decoding circuit 7 encryption / plain culture circuit 8 modulation / demodulation part modem 9 NCU 10 telephone line 11 reading part 12 image processing part 13 transmission function part 14 reception function part 15 recording part

Claims (2)

[Claims] 1. In a facsimile communication method having a function of performing encrypted communication, a transmitting step of encrypting and transmitting a leading portion before encrypting and transmitting an entire image, and a receiving side accurately transmitting the encrypted leading portion. By determining whether or not it can be decrypted based on the signal returned from the receiving side, it is possible to determine whether the receiving side has the same encryption key as the transmitting side, and the same encryption key is used in this determining step. A facsimile communication method comprising: a control step of encrypting and transmitting the image when it is determined to have, and a control step of ending communication when it is determined not to have. 2. A facsimile communication method having a function of performing cryptographic communication, wherein a generating step of creating regular information and encrypted information in an information field of a signal of a pre-communication procedure sent from a transmitting side to a receiving side, Put this encrypted information on the procedure signal and send it to the receiving side,
A determination step of determining whether or not the result decrypted on the receiving side matches the above-mentioned regular information based on a signal returned from the receiving side to determine whether or not the same encryption key is possessed; A facsimile communication method comprising: a control step of encrypting and transmitting the image when it is determined that the determination result of the determination step has the same encryption key, and ending communication when it is determined that the image does not have the same encryption key.