JPS5947876A - Method for encrypting facsimile - Google Patents

Abstract

PURPOSE:To attain an encryption not affected for code error check, by replacing the order of white and black run length between line synchronizing codes. CONSTITUTION:A reading circuit 10 scans a transmission original, converts it into an electric distribution signal and obtains a picture signal. A changing point detecting circuit 11 detects the signal changing point from white to a black and from black to white picture elements, counts the number of picture elements between the signal change points and obtains the white and the black run length. A control circuit 13 switches memory circuits 12a, 12b at each signal changing point and stores the data train of white run length to the memory circuit 12a and the data train of the black run length to the memory circuit 12b. Each run length data is read out according to the data train replacing order table stored in an order converting circuit 14 and processed for the encryption.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a security protection method for a system in which facsimile devices are connected to a communication network and mutually perform facsimile communication.

[Background of the invention]

Using a facsimile machine that performs redundant μ suppression encoding processing,
In order to improve communication functionality and reduce communication costs, communication networks having image information storage and high-speed transmission functions are expected to become widespread in the future.

In such communication networks, it is necessary to reduce the storage memory, improve the transmission efficiency of high-speed transmission lines, and detect code errors between the input facsimile terminal and the storage memory.

Therefore, at the input section of the communication network, decoding processing is performed to check the specified number of pixels, and a dummy code ( (usually called fill pits) are removed to reduce the amount of stored code, and the data is stored in memory. On the other hand, in the communication network output (), in order to match the receiving facsimile device, if the encoded data of the l line is less than the minimum transmission time, the above fill pits are inserted and sent7. When performing facsimile communication with a specific terminal using a communication network such as -C, or when performing facsimile communication of highly confidential documents, it is necessary to encrypt encoded data. this,
In such a case, it is necessary that the encrypted data have no effect on the decoding process for checking the line for code errors at the input section of the communication network. In other words, the encrypted data is
Treated as an abnormal image signal in the decoding process at the input section of the communication network1
(・7. [Object of the Invention] The present invention has been made in view of the above circumstances, and is capable of detecting code errors in a communication network without affecting code error checking processing, etc. in any way. An object of the present invention is to provide a facsimile encryption method that can effectively utilize communication networks.

[Summary of the invention]

The gist of the present invention is to encrypt facsimile image information by changing the order of the synchronization length and black run length between line synchronization codes.

[Embodiments of the invention]

FIGS. 1 and 2 are block diagrams of one embodiment of the present invention, with FIG. 1 showing an example of the configuration of a transmitting side device and FIG. 2 showing a configuration example of a receiving side device. The transmission operation will be explained below. The reading circuit 10 scans the transmitted original and converts it into an electrical signal to obtain an image signal. The change point detection circuit 11 inputs the image signal from the reading circuit 10, detects signal change points from a white pixel to a black pixel, and from a black pixel to a white pixel, and also reduces the number of pixels between the signal change points by 1, 1. Control circuit 1: Memory circuit 1231.1 for each signal change point.
Step 1] is changed to 14/J, and among the run lengths generated for each signal change point, for example, the take string of white run length is sent to the memory circuit 12a, and the take string of black run length is sent to the memory circuit 12a. 121) 7 to store K each
, Next, the control circuit reads each run length from the memory circuits 12a, 121] in a different order than when writing, according to the data string permutation order table for the Jin length length stored in the order conversion circuit 1.1. Read and extract data.

This is the encryption process. , the encoding circuit 15 performs run-length right-bow conversion on this +B'i encoded data,
The facsimile signal is output to the line via the modulation circuit 16 and then received through the communication network (arriving at the Ryj Noack/Milli device).

Next, the receiving operation will be explained with reference to FIG. The demodulation circuit 26 converts the received facsimile signal from the line into received encoded data. The decoding circuit 5 performs run-length decoding processing on the encoded take, and the run-lengths of white and black pixels are reproduced. The memory circuits 22a, 221) are switched at each change point of the black and white pixels by the output of the white run length data string in accordance with the run length decoding order of the received facsimile signal.
The data string of black run length is stored in the memory circuit 22[]. Next, the control circuit 2 selects the first
The data strings of each gin length are read out in the same order as they were written into the memory circuits 1231 and 121 in the figure.
Original? playback a data string of length length. The image signal reproducing circuit 21 reproduces white pixels and black pixels according to the white run length and black run length of this data, and reproduces the original image signal. This image signal is input to the recording circuit 20 and recorded on paper, thereby obtaining a received original.

The encryption method of the present invention will be explained in more detail below.

FIG. 3 shows a specific example of the encryption process and the encryption/decryption process according to the present invention, and FIG. Tamo Tearo 1. In FIG. 3, W is the white run length, B <i;5. ', is the run length. Also, in Figure 3, for ease of explanation, the line consisting of ~＼Z + l'+,,
\to I2. lself.

. . , W6, 136, 12 black and white length/length data strings are transmitted.

Now, generate a take sequence for each run length IK +1 (['
↓According to the order, W,,W,,,W,,...,W,1
to the memory circuit 12a, B, , B2.13. ,−
, 13. , are written to the memory circuit 121]. The data strings of each run length stored in the memory circuit 12, 1.121) are converted into a permutation order table shown in FIG. 4, and then read out. Figure 4 shows the replacement order when there are 15 data strings of black and white lengths;
As shown in Figure 3, the black-and-white run-length Ai text is
If the number of rows is 6, the permutation order (conversion order) of 7 to 15 may be ignored. As a result, the white run length conversion order is 5.5 as indicated by the circles in FIG. :3. /1, 1, 2.6, and using this as the reading order, the data string of the white run length stored in the memory circuit 12; W3. Read out in the order of W41W to lW. In the same way, 1 black run 2I (
The rungs conversion order is 4.2, 6, 3, 1. ．． 5, the data strings of black run length stored in the memory circuit 12I] are B, , B32 . B6. B3,13. ．． 13
Read out in the order of 5. By combining the data strings of each run length read in this way, the transmission data becomes Wl, 134. W3. B2. W4.136. W
, , Ding 33. W2. I3□.

) ■6. I3. becomes.

On the receiving side, the data string W5゜B of this run length,
,W, ,B2. W4. B6. W, ,B3. W2.
B, , W6.135 are converted into a white run length data string w5. w3
．． w4. w, , w2. w6 is a data string B, , B of black run length to the memory circuit 22a. , B6. T3
3. I'3. , B5 are written to the memory circuit 221). The order of the data strings of each run length in the memory circuits 22a and 22b is permuted using the permutation order table shown in FIG. In this case, the white length conversion order is 5 as shown by the circle in Figure 4.
13141 l 1216. This is because, as shown in FIG. 3, the data in the write order 1 of the memory circuit 22a is the fifth data of the transmission data, and the data in the write order 2 of the memory circuit 22a is the fifth data.
The data is the third data of the transmission data, and the following is as follows:
Similarly, the data in the write order 6 represents the (5th data of the send (+T?) data. In other words, the self-run length conversion order 5.3./1, 1, 2.6 is the memory Writing order of circuit 22a 1, 2, 3, 4
, 5, and 6 are given. Therefore, the write order number 4 + 51L from the memory circuit 22a:
By reading the data in the order of '31116, the data strings W, , W2 . W:2,9
1/, 1. W5. W6 is obtained. Similarly, the black run length conversion order is 4, as shown by the circles in Figure 4.
2,6. j, 1. , 5, so the memory circuit 22
I] by reading the data in the order of write order numbers 5.2, 4, 1, and 6.3, the data string B of the original black run length is created.

B2. B3. B4. B5. B6 is obtained 3. The data string of the white run length and black run length is W, ,B
,.

W T3 W , 13...'``6'' B
By synthesizing 6, 2 2 I 3
3 The original transmitted data is decoded.

Note that in Figures 1 and 2, the transmitting side may perform permutation on the encoded data of the data string of each run length, and the receiving side may perform permutation on the received encoded data. The same effect can be obtained by decoding -C.In other words, in FIG. 1, the encoding circuit J5 is provided at the next stage of the change point detection circuit 1], and in FIG.
The same effect can be obtained even if it is provided before the image signal reproducing circuit 21.

Further, the same effect can be obtained by using the same memory and converting addresses in the memory circuits 12a, 121) without separately storing the data strings of each run length. This is the memory circuit 22a, 221)
The same applies to Furthermore, the memory circuits 12'a, 121) and 22a1221) and control circuits 13 and 23 in FIGS. 1 and 2 may be configured to be shared for transmission and reception.

In addition, if the order conversion circuit] 4.2.10 permutation order table, the read-on node IJ - (ItO
It can be obtained by storing it in a memory such as M') or by creating it using a random number generation circuit. In addition, by selectively using multiple permutation order duples (・,) or changing the permutation order in units of several lines, it is possible to complicate the encryption and easily increase the degree of confidentiality1. ] As is clear from the above description, according to the present invention, the data string between line synchronization codes is prioritized, and its own run length,
Since the encryption process is performed by exchanging the black run lengths in each order, the run lengths of white pixels and black pixels do not change, so there is no increase or decrease in the amount of compressed code (and the minimum transmission time Since there is no change in the amount of fill bits inserted for encoded data that is less than Because it is inserted at the end of the process, when run-length encoded data is decoded by a normal decoding circuit, it is detected incorrectly as a decoding error due to a line error when the number of pixels is detected normally. In addition, by performing encryption processing on each line independently, even if the sending/receiving line 4M and the encryption processing become out of synchronization due to a coding error on the line, the encryption processing will not occur one after another. There is no continuation, and 16 can be inserted in a line containing an error code.Furthermore, in the present invention, when no encryption processing is used, normal facsimile communication is possible; By changing the initial setting value that defines a fixed reading order, there is an advantage that the image signal can be normally reproduced only when the initial setting values for transmission and reception match.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a transmitting device according to the present invention;
FIG. 2 is a diagram showing an embodiment of the receiving side device according to the present invention;
Figure 3 is a diagram for explaining the encryption process of the present invention, Figure 4
The figure shows an example of the order in which run lengths are exchanged. 10...reading circuit, 11...change point detection circuit, 12a
, 12b...Memory circuit, 1:3...Control circuit, 11. Order conversion circuit, 15.. Encoding circuit, 10.
・Modulation circuit, 2t) Recording circuit, 21... Image signal reproduction circuit, 22 t1+ 221)... Memory circuit, 23
...Control circuit, 21..Order conversion circuit, ...Decoding circuit, 20..Post-adjustment circuit, 1.Representative patent attorney.Precious wood.
Makoto

Claims (1)

[Claims] (1) Facsimile encryption characterized in that facsimile image information is encrypted by replacing the order of run-length data in accordance with a predetermined rule using a run-length data string between line synchronization codes as a unit. Method.