JPH02210969A - Cryptographic communication method for facsimile equipment, and facsimile equipment - Google Patents

Abstract

PURPOSE:To make the equipment constitution compact and to reduce the cost by using a processing means decided for use between facsimile equipments at transmission and reception sides, and applying transmission and reception of a cryptographic data. CONSTITUTION:An error correction code addition section 11 adds an identification code in a 16-bit sequence of an FSC, an error check section 12 at the receiver side checks the code to discriminate the presence of an error. In the presence of an error, the error check section 12 informs a relevant frame number to a CPU 3 at the sender side to designate a frame to be sent again. When the data is sent to the receiver side without any error, a cryptographic data is decoded in the order of original frames by means of a decoding procedure corresponding to the cryptographic procedure set in a receiver side ROM 5, a recording section 13 is driven and the data is received.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an encrypted communication method in a facsimile machine and a facsimile machine used to carry out the method.

As a recent communication method, facsimile communication using facsimile machines has been increasingly used.

When transmitting confidential data in such facsimile communications, it is necessary to encrypt the data to prevent it from being intercepted via the line.

For this reason, conventional facsimile machines have been configured to include a dedicated encryption device (for example, an encryption device under the trade name 'LEKTORJ' of Pritish Telecom Company) as a means for encrypting confidential data.

However, the above cryptographic devices are expensive and have the disadvantage of increasing equipment costs.

In addition, it is particularly inappropriate to equip low-grade machines such as facsimile machines that are only used for sending or receiving.

The present invention has been made in view of the current situation, and it is an object of the present invention to provide an encrypted communication method for a facsimile machine that enables encrypted communication without being equipped with an expensive encryption device.

Another object of the present invention is to provide a low-cost facsimile device that is itself equipped with an encrypted communication function.

The encrypted communication method in a facsimile device according to the present invention stores the image signal data of a document read by the reading section of the facsimile device on the sending side as one or more block data, and then A means is provided for dividing the block data into a plurality of frame data, storing these frame data as encrypted data in a different order from the reading order, and decoding the encrypted data into the original frame data. The image signal data of the document is sequentially transmitted to the facsimile machine on the receiving side, and the image signal data of the document is recorded.

When the situation arises, encrypted data is sent and received, that is, encrypted communication is performed according to a procedure agreed upon between the sending facsimile machine and the receiving facsimile machine.

1-1 An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention applied to a facsimile machine having sending and receiving functions, and FIG. 2 is a drawing showing a manuscript.

First, the configuration of this facsimile machine A will be explained according to the transmission operation. Place the document in the facsimile machine A, and operate the ten keys and send key on the operation unit 1 to enter the send standby state.

Then, as the document tray moves in the feeding direction indicated by the arrow in FIG.
As shown by b..., one line is read, the read image signal (pixel data) is binarized, and the processed line data is input to the CPU 3. Then, the CPU 3 that receives the line data reads the line data and temporarily stores (accumulates) the line data in the image memory 4 serving as the first storage means.

The image memory 4 has a capacity to store one block of line data (hereinafter referred to as block data), and one block is ECM (Err.

A unit of information that can be sent and received at once when communicating using the (Correction Mode) method, and is composed of a collection of multiple frame data indicated by ■, ■, ■, ■ in Figure 2. .

Next, the CPU 3 reads out the block data once stored in the image memory 4, and encrypts this block data according to the encryption procedure preset in the ROM 5. That is, the order of the block data stored in the image memory 4 in the order of ■, ■, ■, ■ is changed, for example, ■, ■,
It is converted into encrypted data arranged in the order of (1) and (2), and this encrypted data is stored all at once in the image memory 6 as a second storage means.

Here, the number of frame data is not limited to four, but may be any number that can substantially encrypt the text between l block data.

In addition, when this facsimile machine A1 becomes the receiving side, the encryption procedure in the ROM 5 is used as a decryption procedure for decoding the encrypted data into the original block data. For this reason, the contents of the ROM5 of the facsimile machine A on the sending side and the ROM5 of the facsimile machine At on the receiving side (the configuration of the facsimile machine A2 is not shown, but since it is the same as that of the facsimile machine A, the following is The contents of ``corresponding parts are given the same numbers and explained'' are in a corresponding relationship.

In addition, this encryption procedure is not fixed; the encryption method (order of frame data) can be selected (changed) by setting from the operation panel, etc., and the key code for the encryption method can be changed by handshaking. It may also be possible to send and receive a key code and automatically select and set the encryption method corresponding to the key code.

When the encrypted data corresponding to the block data is stored in the image memory 6, at that point the CPU 3 as a transmission control means issues a modulation command signal to the modulator/demodulator (modem) 8, and the network control unit (NCU) 9, a line connection command signal will be issued. Thus, the encrypted data is transferred to line 1.
0 to the receiving facsimile machine At.

Then, transmission and reception between these facsimile apparatuses A8 and At is specifically performed using an error retransmission processing method based on the ECM method.

The details of this error retransmission processing method are as follows.

That is, when the facsimile machine A1 on the transmitting side transmits one block of data, the facsimile machine A2 on the receiving side checks this block data for the presence or absence of errors for each frame data having the structure shown in FIG. The check results are sent back to the sender.

If there is an error, the corresponding frame data is sent again to the receiving side.

However, in FIG. 3, F is a flag, A is an address field, C is a control field, FCF is a facsimile control field, and F is a flag.

No. indicates a frame number, and Fe2 indicates a frame check sequence, and the above-mentioned check is specifically performed as follows.

That is, the error correction code adding section 11 shown in FIG.
An identification code is added to the 16-bit sequence, and this added identification signal is sent to the error check section 12 on the receiving side.
(performs division using the generator polynomial and determines the remainder), and uses the fact that the remainders do not match when noise is introduced via the line during transmission to determine whether there is an error. . If there is an error, the error check unit 12 sends the corresponding frame number to the CPU 3 on the sending side.
It specifies which frames should be retransmitted.

In this way, when one block of data is transmitted to the receiving side without error, the CPU 3 on the receiving side acts as a decoding means.
The encrypted data received in the frame order of ■, ■, ■ is converted to the original frame order by the decryption procedure corresponding to the encryption procedure previously set in the ROM 5 on the receiving side as described above, that is, ■
, ■, ■, ■ are decoded in this order, and then the recording section 13 is driven to perform a recording operation.

Next, the transmission procedure on the transmitting side will be explained according to the flowchart shown in FIG. The CPU 3 on the sending side first determines whether or not a document has been set and the facsimile machine At on the receiving side has been designated by the operator's key operation (Sl). When this is recognized at 1rli, it issues a modulation command signal to the modem 8 and a line connection command signal to the network control device 9, setting it in a transmission standby state (S
2).

Next, the CPU 3 instructs the reading section 2 to start reading the document and causes it to perform a reading operation (S3). and,
The image signal data read by the reading unit 2 is temporarily stored in the image memory 4 in the reading order (S4), and it is determined whether one block of data has been stored (S5).
After confirming that the data for the block has been stored, R
According to the encryption procedure in the OM5, the frame data in the order of ■, ■, ■, ■ is converted into encrypted data in the order of ■, ■, ■, ■, and written into the image memory 6 (S6).

Next, the converted encrypted data is read from the image memory 6, an identification code is added thereto by the error correction code adding section 11, and one block of data is sent frame by frame via the line 10 to the facsimile machine l. ! A! At this time, it is determined whether there is a retransmission request signal from the receiving side (S8). If there is a retransmission request, the corresponding frame data is transmitted again.

Next, the CPU 3 sequentially transmits the next and subsequent block data in the same manner as described above, and when it reaches the final block data, it judges this (S9) and confirms that the transmission of all block data is completed. , issues a line disconnection execution command signal to the network control device 9, and disconnects the line 10 (SIO).

Note that there may be a shortage of frames in the final block data, but in this case, an empty frame (for example, frame data in which all bits are at the white level O) is added, and this frame data is encrypted so that it is recorded as the final frame by the recording unit 13 on the receiving side.

Next, the receiving procedure on the receiving side will be explained according to the flowchart shown in FIG. The CPIJ 3 on the receiving side temporarily stores the frame data transmitted from the transmitting side in the same image memory 4 in this order (311), and then determines whether or not one block of data has been received (512).
When it is confirmed that the data has been received, the error check section 12 performs the above check for each frame data (S13).
.

Then, it is determined whether an error exists or not (514).
If an error exists, a retransmission request command signal including the corresponding frame number is reported to the sending side cpu3 (S15
), the frame data will be received again.

In this way, when all error-free frame data is received, according to the decryption procedure in the ROM 5, ■, ■, ■
The frame data received in the order of .

Thereafter, it is determined whether or not recording of all data has been completed, and when this is confirmed, the connection with the line 10 is severed and the reception operation is terminated.

In the above embodiment, data is transmitted for each block, but if an image memory with a large memory capacity is used, a plurality of blocks of data can be transmitted and received at once. Further, in the above embodiment, the sending and receiving operations are performed by a facsimile device capable of sending and receiving, but the sending operation may be performed between a facsimile device that is only for sending and a facsimile device that is only for receiving. Incidentally, such a facsimile machine dedicated to transmission and reception has the advantage of being low in cost because the number of components can be reduced accordingly.

In the case of the present invention, which is more than one dish, the transmission and reception of encrypted data, that is, encrypted communication, is carried out according to the processing procedure agreed upon between the facsimile machine on the sending side and the facsimile machine on the receiving side. Therefore, confidential data can be sent and received with confidence without fear of eavesdropping.

Furthermore, since the facsimile machine itself performs this processing procedure through software processing, there is no need for an expensive dedicated auxiliary device as in the above-mentioned conventional example. Therefore, the device configuration can be made compact and costs can be significantly reduced.

In particular, according to the invention as set forth in claim 2.3, there is an advantage that a sending and receiving facsimile device equipped with an encrypted communication function can be provided at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to a facsimile machine equipped with sending and receiving functions, FIG. 2 is a drawing showing a manuscript, and FIG. 3 is a drawing showing frame data.
FIG. 4 is a flowchart showing the sending procedure, and FIG. 5 is a flowchart showing the receiving procedure. 2... Reading unit, 3... CPU, 4.6... Image memory, 5... ROM, 13... Recording unit, A+, A
T...Facsimile machine, D...Manuscript. D Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) The image signal data of the original read by the reading unit of the facsimile machine on the sending side is stored as one or more block data, then this block data is divided into multiple frame data, and these frame data are read. It is stored as encrypted data in a different order than the
A code for a facsimile machine characterized in that the encrypted data is sequentially transmitted to a receiving facsimile machine equipped with a means for decoding the encrypted data into original frame data, and the image signal data of the original is recorded. Communication method. (2) a first storage means for storing image signal data of the original read by the reading unit as one or more block data; and dividing the block data into a plurality of frame data;
Further, it is characterized by comprising a second storage means for storing these frame data as encrypted data in an order different from the reading order, and a transmission control means for sequentially transmitting the encrypted data to a receiving facsimile machine. Facsimile machine for sending. (3) a receiving unit that is read as one or more block data by the reading unit of the sending facsimile device and receives the block data as encrypted data divided into multiple frame data different from the reading order; The present invention is characterized by comprising a decoding means for decoding the encrypted data as frame data corresponding to the reading order of the reading section, and a recording section for sequentially recording the frame data decoded by the decoding means. Receiving facsimile machine.