JPS6270982A - Filing system - Google Patents

Abstract

PURPOSE:To improve the secrecy of documents by coding the pictures with high efficiency that are converted into a digital style after the photoelectric transducing, sampling and quantization and storing these codes in a file after ciphering them. CONSTITUTION:The information on a document 3 is scanned by a scanner 4 and a digital picture 51 of the input document is outputted after the photoelectric transducing, sampling and quantization. At the same time, the picture control information 52 is obtained as the output of the scanner 4. Both the picture 51 and the information 52 are stored in a buffer memory 5. Then the picture 51 is converted into a Huffman MH code 54 by an improved MH coding processor 7 and stored in the memory 5. A control part 2 adds the random numbers to the MH code data 54 to produce the random number addition data 55. Both the data 55 and the information 52 are converted into the cipher data 56 by a ciphering processor circuit 8 and stored in the memory 5. Then the part 2 stores the data 56 and the directory information 53 in a file 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a document filing method, and particularly to a filing method suitable for maintaining the precision of document images stored in image files.

[Background of the invention]

In the conventional document image filing method, data indicating the security level is attached to the management information of the filed document, and a mechanism is set up to prevent display commands from being accepted for documents with a high security level. . (
For example, ``Practical Application of Document Processing Program (DISPS)'', Telecommunication Research Institute Research Practical Application Report, Vol. 31, No. 8
No. (1982) pp. 1509-1522) However,
If the management program was modified to ignore data indicating the security level, documents with a high security level would also be displayed.

To address this problem, it is possible to encrypt the image converted into a digital format and then store it in a file device, but this poses the following problems.

A digital image is expressed as one-dimensional data by P (i). Encryption of P(]) is expressed by the following equation.

Q (i) = P (j) +K (i) where + is a bitwise exclusive OR.

Further, K(i) is a key code, which is usually a pseudo-random number having a certain period. In the commonly used method, the key code is 56
Since it is expressed in bits (7 bytes), if one image is expressed as one pixel and one bit, the period of the key code is 56 pixels. In normal use, this cycle is considered to be long enough, but in document images, there is a lot of redundancy and the effectiveness of the encryption is not balanced. That is, there are often white areas in a document image, and in particular, the top area of the document is often white.

Therefore, someone trying to decipher the code will notice that a certain part (especially the beginning part) of the encrypted image Q'(i) is a white image W(1
) is encrypted, and Q' (i)=
The key code K(]) can be estimated by adding W(i) to both sides of W(i)+K(i) to obtain K(i)=Q'(i)+K(i).

If the white image W(1) is represented by O, then Q'
It goes without saying that (i) directly gives the key code K(1).

On the other hand, in recent document image files, in order to reduce the storage capacity of the file, instead of storing the document image as it is in the file, the image is encoded with high efficiency and stored. As a highly efficient encoding method, an improved Huffman code (hereinafter referred to as MH code) is used. M.H.
Because the encoded image has reduced redundancy, encrypting it is more difficult to decipher than directly encrypting the original image. However, even in this case, since the Mt code in the white image part has a fixed format, it can be decoded by assuming the MH code as the representation of the white image W(i) in the above decoding method.

[Purpose of the invention]

An object of the present invention is to realize a document image filing method that enhances the security of documents.

[Keystone of invention]

In order to achieve such an object, in one embodiment of the present invention, H,7 is used to store the text rF image 4a in a file,
A document image is encoded using a high-efficiency encoding method such as an MH code, and a meaningless code such as a pseudorandom number is inserted during the encoding and then encrypted to make it difficult to decode. In other words, 1. By inserting the Senmoho code, the shape of the MI-I code representing the white side ff1 (W(i) is disrupted, and the application of the above deciphering method becomes a chore.Authorized users cannot access the encrypted data. After restoring the image, if the meaningless gradient code inserted at a known position is removed and M)I decoding is performed, originality can be obtained.

In addition, in other IUs of the present invention, in addition to storing the document image in a file, after inserting meaningless data made from pseudorandom numbers into the document image (for example, between scanning lines), It performs highly efficient encoding and encrypts this code to make it difficult to decipher. This method slightly reduces encoding efficiency, but makes decoding extremely difficult. The authorized user restores the encrypted data, performs MH decoding, and then removes meaningless codes inserted at known positions to obtain the original image.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an apparatus that implements the filing method of the present invention. Each part of the device is connected to a bus 1-, and the overall operation is controlled by a control part 2. The operation of the entire device is roughly divided into a bodice mode and a search mode.

In the storage mode, information on document 3 (text image)
is scanned by the scanner 4. The scanner 4 performs photoelectric conversion, sampling, and quantization to output a digital image of the input document. In the following explanation, this digital image is assumed to be binarized into one pixel/bit, but it may be a multivalued digital image or a color image. This digital image 51 is stored in the buffer memory 5 via the bus 1 2. Further, image management information 52 is simultaneously obtained as the output of the scanner 4, and these are also stored in the buffer memo I75. Here, the image management information 52 includes the total data length,
It consists of vertical and horizontal mesh sizes, the number of bits representing the density of one pixel (in the case of a multivalued image), or a code representing the color (in the case of a color image).

When the scanner operation is completed, the operator inputs the document number, search information, security level, key code for encryption, etc. from the console 6 according to instructions from the control unit 2. These document numbers, inspection information, security protection level, etc. can be automatically input manually by recognizing the content of the document if the target is limited. Determine the address within the file to be stored, and create information that associates this address information with the above sentence, search number, search information, security level, etc. as Tiref1-ri information 53, It is stored in the buffer memory 5.

The image data 51 is converted into M by the MH encoding processing device 117.
It is converted into an H code 54 and stored in the buffer memory 5. The control unit 2 performs random number addition processing on the MH code data 54 to create random number addition data 55. Details of the random number addition process will be described later. Random number additional data 5
5 and image management information 52 are converted into encrypted data 56 by the encryption processing device 8 and stored in the buffer memory 5.

The control unit 2 stores the above encrypted data 56 and directory information 53 in the file 9. File 9 is composed of multiple files, one of which is used to store encrypted data 56,
The other one may be used to store the contents, ie, the directory information 53.

Next, the operation in search mode will be explained. The user provides his or her identification number (name code, etc.) and password to the control unit 2 from the user console 10. The console 10 may be shared with the console 6. The control unit 2 is
After confirming that the user is a genuine user using the user identification number and password correspondence table set in advance in the internal memory, the process proceeds to the next step.

The user gives the control unit 2 the document number that he or she wants to read. At that time, using a search program running on the control unit 2,
The document number may be searched by giving search information instead of the document number. The control unit 2 first reads the directory 1 information of all documents from the file 9, and
Directory information 53 corresponding to the given document number is extracted from there. The control unit 2 compares the security protection level in the directory information with the security permission level set in advance in the internal memory for each user, and determines the security permission only when the document can be disclosed to the user. Proceed to the next process only when the level is higher than the security level (assuming that important documents have a high security level). That is, the control unit 2 finds the storage address in the file 9 corresponding to the given document number, and reads the encrypted data 56 stored at this address from the file 9 into the buffer memory 5. The encrypted data 56 is converted into random number additional data 55 and image management information 52 by the encrypted restoration processing device 11.
and stored in the buffer memory 5. Control part 2
Now, random number removal processing is performed on the random number added data 55 to restore the M and H codes 54. Since the random number removal process is the reverse process of the random number addition process, its explanation will be omitted. The MH code 54 is converted into image data 51 by the MH decoding processing device 12 and stored in the buffer memory 5. The above image data 51 is stored on the display device 13 together with the image management information 52.
is sent to and displayed. Here, the display device includes a printing device.

Figure 2 shows the flow of random number addition processing.
3 is a flowchart shown in ramAnalysis Diagaram) format.

In FIG. 2, 201 is a part for inputting the MH code M(i), i=l~L, where L is the length of the MH code. In step 202, the output code counter j is set to O. 203 is a control that repeats the following processes 204 to 207 L times for 1=1 to L. In 2o4, it is determined whether the loop control variable 1 is of the (mc+b) type. Here, c, b
is an integer constant, and m represents an integer multiple. If i is not in the form (mc+b), the output code H(j) is determined at 205 as j←ko+1. The input M (i) is reproduced as H(j)=M(i). When j is in the form (mc+b), after repeating the process in 207 once in 206, 2
04 processing is performed. Here, 207 is the random number n(
1,]←-i+t, p4-pal, H(j)"R(p
). p is a random number counter and may be reset once at the beginning. As described above, input code 0
T random numbers are inserted for each random number.

Since the value of j at the end of the group in 203 gives the length L' of the random number additional data, in 208, j is substituted for L'.

Next, another embodiment according to the present invention will be described. The configuration of the device is the same as that shown in FIG. 1, but the processing of the control section 2 is different. 6' to explain only the differences from the first embodiment? In the ji product mode, image data 51 input by the scanner 4
A pseudo pattern made of random numbers is inserted into the image to create a pseudo image pattern.

Insertion of random/number patterns is almost the same process as shown in FIG. The above pseudo image pattern is subjected to MJ (encoding and encryption) and stored in file 9.

In Yusaku Mort, the reverse processing of Kitaki is performed.

Next, a third embodiment of the present invention will be described. The configuration of the device is almost the same as in FIG. 1, except for the presence of a communication processor 14 and a communication path 15. Only the differences from the first embodiment will be explained.

File 9 is not connected directly to bus 1, but via communication processor 14 and communication path 15. The input image data is subjected to MH encoding, random number addition, and encryption in the same manner as in the first embodiment, and is provided to the communication processor 14. The communication processor 14 sends the encrypted image data and directory information to the file 9 via the communication path 15 to be stored therein.

In the search mode, the control unit 2 obtains directory information of necessary image data from the search information and issues an image transfer request to the communication processor 14. The communication processor 14 sends directory information to the file 9 and receives the image data stored in the file 9 (which has been subjected to MH encoding, random number addition, and encryption) via the communication path 15. take.

The subsequent processing is the same as in the first embodiment. This embodiment is particularly effective when image files are shared by a large number of image terminals or search terminals.

In the above description, a document image was taken as an example, but it is clear that the present invention can also be applied to general pattern information such as vector-expressed graphic data and audio waveform data.

Furthermore, in the case of documents that are not confidential, it is clear that encryption processing can be omitted, and it is easy to implement control to perform or omit encryption processing depending on the case. Therefore, the explanation will be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to protect confidential documents stored in document files. ! becomes stronger.

[Brief explanation of drawings]

1 and 3 are block diagrams showing the configuration of an apparatus implementing the filing method of the present invention, and FIG. 2 is a flowchart of random number addition processing in the embodiment of FIG. 1. ]... Bus, 2... Control unit, 3... Document, 4... Scanner, 5... Memory, 6 - Console, 8...
Encryption processing device, 9...File, 11...Decryption processing device, 13...Display device, 14...Communication processor, 15...3ffl 4t'',
,,, + Par, agent patent attorney Katsuo Ogawa'・4~' -~. Second

Claims (1)

[Claims] 1. High-efficiency encoding of an image converted into a digital format through photoelectric conversion, sampling, and quantization, and encrypting the highly-efficiently encoded code, and then storing it in a file device. A filing method characterized by: 2. In the filing method described in claim 1, a meaningless code is inserted between the high-efficiency codes in a predetermined manner, the code after the insertion process is encrypted, and then the file device is A filing method characterized by storing information. 3. A filing method according to claim 1, characterized in that the encrypted image is transferred to a filing device via a communication circuit. 4. The filing method according to claim 1, wherein the encrypted image stored in the file device is transferred via a communication circuit.