JPH0678071A - Facsimile communication equipment - Google Patents

Abstract

PURPOSE:To provide a facsimile(FAX) communication equipment capable of attaining highly reliable secret communication without interrupting communication with a terminal which does not support ECM. CONSTITUTION:In a negotiation before the start of FAX communication, whether ECM with a communicated terminal 1B has been established or not is detected based upon a result obtained by decoding a slow signal by a slow decoding part 24. When the ECM has not been established yet, an image signal sent from a G3 terminal 1A is directly sent to a line through a change-over switch 22, and when the ECM has been established, the image signal from the G3 terminal 1A is entered into a cipher processing part 27 through change- over switches 22, 23 and a rapid decoding part 25, ciphered by a ciphering part 28, coded by a rapid coding part 26, and then sent to the line through the switches 23, 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile communication apparatus which is connected to the outside of a facsimile terminal and serves as a function of preventing leakage of facsimile communication information.

[0002]

2. Description of the Related Art Conventionally, a facsimile terminal as disclosed in Japanese Patent Laid-Open No. 63-104579 has been proposed as a measure for preventing communication information leakage in facsimile communication. This facsimile terminal has an encryption processing unit inside the terminal and encrypts the image signal by the encryption processing unit and transmits the image signal so that another terminal cannot decrypt the image signal.

However, in the conventional facsimile terminal of this type, since the image signal is encrypted by the encryption processing unit and transmitted in all communications, communication is performed with a facsimile terminal that does not have a decryption means for the encrypted data. However, the wide area communicability of G3 facsimile communication for general facsimile terminals is impaired. Further, in the above-mentioned conventional facsimile terminal, for encryption, for example, although a process of changing the transmission order of image signals for each line is performed, no measures are taken against such an error in transmission of image signals. It was not taken.

Therefore, although the image signal is transmitted after being encrypted, there is no guarantee that the encrypted data will be correctly received by the receiving side, and the secret leakage prevention function is extremely unreliable.

[0005]

As described above, since a facsimile terminal internally having an encryption processing unit has been used as a measure for preventing information leakage in facsimile communication, a decryption processing unit suitable for the encryption processing unit is conventionally used. There is a problem in that it is not possible to communicate with a terminal that does not have it, and the wide area communication of general G3 facsimile communication is impaired. Further, in the conventional facsimile terminal of this type, in the standard G3 mode facsimile communication, when an error occurs on the transmission line, it does not have a function of correcting the error and retransmitting it, and thus it is difficult to be familiar with the encryption processing. There is also a problem that only an extremely reliable information leakage prevention function can be realized.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above problems and to provide a facsimile communication apparatus capable of realizing a highly reliable information leakage prevention function without impairing the wide area communication property of general G3 facsimile communication.

[0007]

A facsimile communication apparatus of the present invention is a facsimile communication apparatus which is connected to the outside of a facsimile terminal so as to be located on the front side of a line, and is transmitted from the connected facsimile terminal. An encryption / decryption processing means for encrypting an image signal to be transmitted to the line and decrypting the encrypted signal coming from the line for reception at the connected facsimile terminal; and an error occurred on the transmission line during communication. In this case, the detecting means for detecting whether or not the facsimile terminals involved in the communication support the error correction mode capable of coping with the resending process prior to the communication, and the detecting means supports the error correction mode. Depending on whether or not it is detected, the signal path and the route via the encryption / decryption processing means are determined. It constituted a non signal path selectively and a switching control means for switching formed.

[0008]

As is well known, CCITT SG (VIII)
In ECM (Error Correction Mode), which is an optional standard method of G3 mode, which was provisionally recommended in 1987, an error correction method of retransmitting an image signal in frame units is presented. Therefore, in the present invention, focusing on the ECM, a facsimile communication device having an encryption / decryption processing means is connected to the outside of the facsimile terminal in order to perform secret communication limited to the ECM.

In the facsimile communication apparatus of the present invention, a signal path which does not pass through the encryption / decryption processing means can be selectively formed in the case other than the ECM to cope with normal G3 facsimile communication. It does not impair the wide area communication of the communication. Further, in the case of ECM, a signal path passing through the encryption / decryption processing means is selectively formed, all image signals are encrypted, and secret communication is performed to prevent leakage of communication information. . Here, in detecting the ECM, attention is paid to a low-speed signal (procedure signal) used in negotiation before transmitting / receiving an image signal in G3 facsimile communication.

That is, the facsimile communication apparatus of the present invention has a low-speed decoding unit, and the low-speed decoding unit allows the ECM of the option standard system of the G3 mode from the low-speed signal.
To detect. When it is confirmed that the ECM has been established, the image signal is taken into the encryption processing unit through the high-speed decryption unit before being sent to the line, and the data encrypted by this encryption processing unit is transmitted through the high-speed encoding unit. Send to.

On the other hand, on the receiving side, the image signal coming from the line is taken into the encryption processing section through the high-speed decoding section, and the data decoded here is received by the receiving-side facsimile terminal via the high-speed encoding section.

In the present invention, when an error occurs on the transmission line during the secret communication during the ECM, the above ECM is used.
Since the image signal for the error correction is retransmitted according to the procedure of (1), the encrypted data will surely arrive at the other terminal, and the reliability of the information leakage prevention function can be significantly improved.

[0013]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of a facsimile communication system using a facsimile communication device according to an embodiment of the present invention. In FIG. 1, the facsimile communication devices 2A and 2B of the present invention are connected to the outside of the corresponding G3 facsimile terminals 1A and 1B so as to be located on the front side of the line, so that they are accommodated in the public network 3. There is. Here, as the G3 facsimile terminals 1A and 1B, particularly, the ECM of the G3 mode option standard system is used.
A terminal that supports is assumed.

The facsimile communication devices 2A and 2B have the same configuration, and each has an external connection terminal 21, changeover switches 22 and 23, a low speed decoding unit 24, a high speed decoding unit 25, a high speed encoding unit 26, and an encryption processing unit. 27, an encryption unit 28, a decryption unit 29, signal lines 30, 31, 32, a tone signal generation detection unit 33, a network control unit (NCU) 34, and a man-machine interface unit 35. Here, the changeover switch 22 is normally on and is controlled to be off at the time of encryption / decryption of the image signal, that is, at the time of secret communication.

The change-over switch 23 is a switch for deciding the direction of encryption / decryption of the image signal, and is changed over to the side a during transmission of the facsimile terminals 1A and 1B and to the side b during reception. The changeover switch is composed of two switches, SW2 and SW2 ', which are interlocked and controlled for changeover.

The low speed decoding section 24 is for decoding low speed signals of the G3 protocol. The high speed decoding unit 25
It decodes a high-speed signal, that is, an image signal in G3 facsimile communication. Similarly, the high speed encoding unit 26 encodes a picture signal which is a high speed signal.

The encryption processing unit 27 has a function of partially buffering high-speed and low-speed data and a function of deciphering the contents of the high-speed and low-speed data.
Data is exchanged on the route to the route No. 6 and on the route from the high speed decoding unit 25 to the high speed encoding unit 26 via the decoding unit 29.

The encryption unit 28 is for encrypting the data transmitted on the data exchange path. The decryption unit 29 decrypts the encrypted data transmitted on the data exchange path and decrypts it.

The signal line 30 is a line for detecting a fallback of the high-speed modem by the G3 protocol and transmitting a switching control signal for the high-speed decoding unit 25 and the high-speed encoding unit 26. According to the ECM protocol, the signal line 31 has a path from the high speed decoding unit 25 to the high speed encoding unit 26 via the encryption unit 28 and a path from the high speed decoding unit 25 to the high speed encoding unit 26 via the decoding unit 29. Is a line for transmitting a control signal for selectively switching the changeover switch 23 in accordance with the data exchange direction in. The signal line 32 is a control signal transmission line for switching the changeover switch 22 to the off side when the data exchange path is switched based on the control signal on the signal line 31.

The tone signal generation / detection means 33 is for generating and detecting various tone signals corresponding to a secret communication activation command or the like in accordance with the command operation. NCU34
Is for performing network control between the G3 facsimile terminal 1 and the public network 3. Man-machine interface 35
Is provided with a ten-key pad, various switches, an indicator lamp, etc., and functions as an input unit for a secret communication activation command and the like.

An outline of the communication procedure in the communication system having such a configuration will be described with reference to FIG. First, at the start of communication, the operator on the transmitting side uses the facsimile communication device 2
The ID number of the partner terminal 1B is input by the ten-key pad of the man-machine interface unit 35 of A.

The encryption processing unit 27, based on the above input,
From the telephone number / ID table prepared in advance,
The telephone number corresponding to the D number is read and dialed [Fig. 2 (a)]. NCU34 by this dialing
Starts, and the communication path between the facsimile communication devices 2A and 2B is first connected (S201).

Next, the facsimile communication apparatus 2A operates the man-machine interface section 35 to start secret communication [FIG. 2 (b)]. By this operation, the facsimile communication device 2A sends a secret communication start instruction to the receiving side facsimile communication device 2B by the tone signal generated from the tone signal generation detection unit 33 (S202).

In the receiving side facsimile communication device 2B,
In accordance with the above instruction, the tone signal generation detection unit 33 in the own device
Sends back the ID number of its own device to the sending side (S20
3). Further, the facsimile communication device 2A on the transmitting side performs a confirmation process of the ID number received from the receiving side [FIG. 2 (c)].

Here, if it is found that the ID number matches the ID of the terminal registered in advance as the target terminal for the secret communication, the facsimile terminal 1A on the transmitting side.
The call path between the facsimile terminal 1B and the facsimile terminal 1B on the receiving side is connected (S204).

After that, the ECM procedure is started between the facsimile terminals 1A and 1B, and first, the negotiation between the two terminals is performed by the communication of the low speed signal prior to the transmission of the image signal (S205). After the completion of this negotiation, the transmission of the image signal from the facsimile terminal 1A to the facsimile terminal 1B is started. At this time, the image signal is encrypted on the transmitting side and the encrypted data is decrypted on the receiving side to keep it secret. Communication is realized (S206).

The specific processing of this secret communication will be described in detail with reference to FIG. That is, FIG. 3 shows an example of the ECM procedure executed after the communication path between the transmitting side facsimile terminal 1A and the receiving side facsimile terminal 1B is connected through the procedure shown in FIG. 2 (S204). Is.

The ECM procedure shown in FIG. 3 is composed of the processes of S301 to S312.
In the process of progressing to the step, the facsimile communication device 2A on the transmission side pays attention to the digital command signal (DCS) and
The encryption processing unit 27 recognizes through the low-speed decryption unit 24 that the above has been established.

Thereafter, in the facsimile communication device 2A, when it is confirmed that the procedure has proceeded to S305,
Control signals are sent from the cryptographic processing unit 27 through the signal lines 31 and 32, respectively, whereby the changeover switch 22 is turned off and the changeover switch 23 is changed over to the a side.

After that, when the image signal is transmitted from the facsimile terminal 1A (S306), the image signal is fetched from the high speed decryption unit 25 to the encryption processing unit 27 via the changeover switches 22 and 23. An example of the format of the image signal at this time is shown in FIG.

In the encryption processing unit, the received image signal is encrypted by the encryption unit 28, and this is encrypted by the high speed encoding unit 2.
6. Send to the line through the changeover switches 23 and 22. At that time, the encryption by the encryption unit 28 is as shown in FIG.
Only the facsimile information D1 in the image signal shown in FIG.

On the other hand, in the facsimile communication apparatus 2B which receives the above-mentioned encrypted data, the changeover switch 22 is turned off and the changeover switch 23 is changed to the b side. Therefore, the received encrypted data in the facsimile communication device 2B is fetched from the high speed decryption unit 25 to the encryption processing unit 27 through the changeover switches 22 and 23.
Here, the encryption processing unit 27 decrypts the encrypted data by the decryption unit 29, and then makes it arrive at the facsimile terminal 1B through the high-speed encoding unit 26 and the changeover switches 23 and 22. After that, the facsimile communication device 2 on the transmission side
In A, the encrypted data obtained by the above-described encryption processing is transferred to S31.
It continues to send it to the facsimile communication apparatus 2B on the other side until the procedure of 2.

Even when an error occurs on the transmission line during the secret communication accompanied with the encryption process, the ECM is established, and therefore the device for facsimile communication on the other side is retransmitted by the retransmission process shown in S308 to S309. The image signal can be reliably transmitted to 2B. Here, as described above, the image signal transmitted to the receiving side is encrypted, and the measures for preventing secret leakage are complete.

As described above, according to the present invention, the low-speed decoding unit for detecting the ECM of the G3 mode option standard system is provided in the facsimile communication apparatus connected to the outside of the facsimile terminal so as to be positioned on the front side of the line. Therefore, as a result of the detection, the encryption process can be performed only during ECM. This means that encryption processing is not performed during non-ECM. Therefore, in non-ECM, general G3 facsimile communication can be dealt with, and the wide area communicability of this type of facsimile communication can be maintained.

Further, since the facsimile communication apparatus of the present invention is provided with the man-machine interface section and the tone signal generation detecting section, if the speed dial is registered in advance, the ID number can be entered to enter the other party's side. It is possible to call the facsimile communication device, confirm the ID, and then notify the start of the secret communication.

Also, the encrypted image signal is decrypted and sent to the corresponding facsimile terminal. At this time, if an error or the like occurs on the line, the resend processing is all performed by the facsimile involved in the communication. Since it can be processed by both terminals,
The reliability of the secret communication function can be enhanced with a relatively simple configuration.

Further, according to the above-mentioned configuration including the man-machine interface section and the tone signal generation / detection section, tone signals corresponding to various commands can be transmitted, and for example, a center apparatus having a storage function as the other party is assumed. If a secondary address or the like required for the service of the center is sent by a tone signal, a facsimile mail system having a secret communication function can be constructed.

FIG. 5 is a schematic view of a facsimile mail system of this type. In the public network 3, facsimile terminals 1A to 1N for connecting facsimile communication devices 2A to 2N according to the present invention, respectively, and a storage exchange device. 4 are accommodated. Here, the storage exchange device 4 is configured to include a facsimile communication control unit 41, a central control unit 42, and an image storage unit 43. For example, an image signal received from the facsimile terminal 1A is temporarily stored in the image storage unit 42. Accumulated in.

When the facsimile terminal 1N attempts to receive the stored information, for example, a secret communication instruction is issued from the facsimile communication device 2N connected to the outside of the terminal 1N by a predetermined operation on the man-machine interface section. You can send it. As a result, the facsimile terminal 1N
Then, the operator can receive the above-mentioned accumulated information at a convenient timing by the secret communication including the ECM procedure, so that the facsimile mail system having the secret communication function can be constructed. Further, in this system, when the encryption device requires a key, the storage / exchange device side can manage the key to provide a facsimile mail system having a confidentiality function.

[0040]

As described above, according to the facsimile communication apparatus of the present invention, it is arranged as the external connection device of the facsimile terminal on the front side of the line, the ECM of the G3 mode option standard system is detected, and the ECM is detected. Since the encryption / decryption processing is performed only at times, the encryption / decryption processing can be canceled during non-ECM to deal with general G3 facsimile communication, and the wide area communication property of this type of communication can be maintained.

Further, in the ECM, communication information can be prevented from leaking by performing secret communication by encryption / decryption processing. At that time, even if an error occurs on the transmission path, the above-mentioned EC
Since the retransmission process can be dealt with by the M procedure and the retransmission process can be entrusted to the control between the facsimile terminals involved in the communication, the reliability of the secret communication function can be significantly improved with a relatively simple configuration. it can.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a communication system using a facsimile communication device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of a communication procedure in the communication system shown in FIG.

FIG. 3 is a diagram showing details of an ECM procedure included in the communication procedure shown in FIG.

FIG. 4 is a diagram showing an example of a picture signal format which is a target of encryption processing in the ECM procedure.

FIG. 5 is a schematic configuration diagram of a facsimile mail system which is another embodiment of the communication system using the apparatus for facsimile communication of the present invention.

[Explanation of symbols]

 1A, 1B G3 facsimile terminal 2A, 2B facsimile communication device 21 external connection terminal 22, 23 changeover switch 24 low-speed decoding section 25 high-speed decoding section 26 high-speed encoding section 27 encryption processing section 28 encryption section 29 decryption section 30 , 31, 32 Signal line 33 Tone signal generation / detection unit 34 Network control unit (NCU) 35 Man-machine interface unit 3 Public network 4 Storage / exchange device 41 Facsimile communication control unit 42 Central processing unit 43 Image storage unit

Claims (3)

[Claims] 1. A facsimile communication device connected to the outside of a facsimile terminal so as to be located on the near side of the line, and encrypts an image signal transmitted from the connected facsimile terminal and sends the encrypted image signal to the line. , An encryption / decryption processing means for decrypting an encrypted signal coming from the line and receiving it at a connected facsimile terminal, and a retransmission processing by facsimile terminals involved in the communication when an error occurs on a transmission line during communication Detecting means for detecting whether or not the error correction mode capable of coping with the above is supported prior to the communication, and the encryption means depending on whether or not the detecting means detects that the error correction mode is supported. / A switch for selectively switching between a signal path passing through the decoding processing means and a signal path not passing through it An apparatus for facsimile communication, comprising: a replacement control unit. 2. The detection means detects the support status of the error correction mode from a procedure signal exchanged between corresponding facsimile terminals for negotiation before the start of G3 facsimile communication. Facsimile communication device. 3. A man-machine interface means and a tone signal generation / detection section for generating a tone signal corresponding to an operation by the man-machine interface means and detecting the tone signal, and a storage function of an image signal. Access to the center device with a desired timing,
The facsimile communication apparatus according to claim 1 or 2, wherein the accumulated information can be received as mail information by secret communication.