JP3610642B2 - Document encryption / decryption device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to encryption / decryption of moving image / stopped image and written image information such as characters / symbols that can be viewed and heard on the screen.
[0002]
[Prior art]
In recent years, multilingual programs such as television broadcasts, N-ISDN, B-ISDN, high-speed LAN, and other networked images such as educational videos and movie / appreciating painting images are added with voices and the like. A communication medium environment provided as media information has been prepared. The book image information is provided online via the above network or provided on demand. However, these programs are provided for a fee only for contracted subscribers for the purpose of use or viewing, so they are provided by being encrypted in units of programs. When using or viewing programs, they are decrypted in units of programs. Will use or appreciate.
[0003]
The program providing method in the conventional multimedia information paying system is so-called secret communication, which is provided by the following means.
In other words, the information source transmits the transmitted information or all pages or frames of the program by performing encryption processing in page units or frame units, and the information encrypted at the receiving end is transmitted in page units or frame units. All pages or all frames were decoded and provided to the user. Such objects include CATV service and BS / CS broadcast service.
[0004]
In addition, a large number of “programs” are prepared and the user selects each program, and the information transmission source transmits only the program selected based on the program selection information from the user to the user end through a dedicated line or the like. It was. Such objects include CATV services and database services provided in a video on demand format.
[0005]
[Problems to be solved by the invention]
The viewer's request for such multimedia information is that a “program to be viewed” can be easily selected from a plurality of provided programs, and that only a specific “scene / screen” in the program can be particularly appreciated. “Information you want to know” can be easily obtained, etc. However, since the above-mentioned conventional providing system encrypts each program, it focuses only on specific scenes and images in the encrypted program. No system or operating means is provided to decrypt and pay only for this decryption part.
[0006]
Since such or a system or operation means is not provided, various kinds of users, for example, specific images / partial images / specific pages / paragraphs of specific sentences, etc. scattered or scattered in the program / There was an inconvenience that it was not possible to satisfy the request for browsing or obtaining only specific terms / special expressions / specific charts.
[0007]
The present invention is an invention created to solve such a problem. The decryption is performed by individually decrypting each phrase and each screen in a program provided by being encrypted so as to be provided for a fee. The object is to provide means that can be easily viewed or obtained by paying a fee for the part.
[0008]
[Means for Solving the Problems]
The above-described problems are solved by the present invention configured as follows.
FIG. 1 is a principle diagram of the present invention, and FIG. 1A is an encryption apparatus according to claim 1, in which a plurality of pixels constituting a document are arranged, and color information of each of the plurality of pixels is displayed. The present invention is applied to a document information encryption apparatus that displays document information that is given meaning by chain expansion or localization.
[0009]
In the figure, reference numeral 1 denotes a storage means for storing a plurality of pixels constituting an original document, and stores a plurality of pixels that are to become a two-dimensional array when displayed on a screen. Reference numeral 2 designates numbering means for designating a pixel at a position to be encrypted and assigning the number to the pixel. When encrypting one screen, all pixels in the screen are designated, and a specific position in one screen is designated. When encrypting a pixel, the position of the pixel is individually specified. Reference numeral 3 denotes reading means for encrypting the numbered pixels designated by the numbering means 2, and 4 denotes one or more factors constituting the read pixels (for example, a factor “3 which is the three primary colors of light” Red, factor “green”, factor “blue”) are operating means, and 5 is a storage means for storing document information specifying the position of the encrypted pixel.
[0010]
FIG. 5B is the decoding apparatus according to claim 2, wherein a plurality of pixels constituting the document are arranged, and the document is made meaningful by chain expansion or localization of the color information of each of the plurality of pixels. This is applied to an information decoding apparatus.
[0011]
In the figure, 5 is a storage means provided in the decryption device for storing the document information specifying the position of the encrypted pixel, 6 is a reading means for reading out the encrypted pixel from the document information, 7 Restoring means for returning the operation of the operator from the encrypted pixel, and 8 is a display means for decoding and displaying the pixel at the designated position of the encrypted document information.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 is a control procedure for encryption and decryption when the present invention is applied. In FIG. 2, the first stage of the transfer 200 is a process on the transmission side, and the second stage is a process on the reception side.
[0013]
That is, the transmission side converts an analog signal such as a TV signal into a digital signal by an analog / digital (A / D) conversion unit 101 and supplies it as image information 102 of the digital signal. This digitized image for each screen is encrypted 103 on a pixel basis, and then, in order to perform transmission at high speed, compression processing 104 is performed on all transmitted images, and transfer 200 to the reception side is performed.
[0014]
The receiving side that has received this compressed image signal performs decompression processing 301, and further performs decoding 302 for each pixel for each screen to restore the digital signal image information 303 and display it on the display screen 304. is there.
[0015]
In the embodiment of the present invention, encryption is performed by designating pixels individually. Here, three types of element signals are adopted as factors constituting the pixel. Incidentally, as the element signal, a color signal that fulfills the purpose of encryption is adopted. For example, if all specified pixels are to be monochromatic, it is effective to use three primary colors of light (R, G, B), or encryption. When it is desired to process the image by luminance adjustment, it is effective to use the luminance signal (Y) and the two color difference signals (R−Y) and (B−Y). Alternatively, other color signals (for example, hue, brightness, and saturation) can be used depending on the purpose.
[0016]
The following means is adopted as an encryption method for the element signals constituting the above three types of pixels. The first encryption method is “addition” processing for each element signal of the pixel to be encrypted, and the second encryption method is “replacement by pattern” processing.
[0017]
When the simultaneous color development of a digitally processed image is made full color (common name: 16.77 million colors) and displayed in the three primary colors of light (R, G, B), each component bit is 8 bits (1 byte). In the first “addition” processing described above, color conversion can be performed by performing arithmetic processing (for example, addition of specific value = α) for each one byte. However, if an arbitrary α is set, the color after conversion cannot be predicted, so that the color of the original pixel is simulated in advance so that it can be converted into a desired color. Furthermore, since it is assumed that an overflow occurs in simple addition and information for decoding is lost, it is considered to store overflow bits by addition.
[0018]
In the second “replacement” process described above, a pattern table that replaces all patterns (256 patterns) of 1 byte for each element is prepared so as to be replaceable. The above replacement pattern table is collated from each 1-byte pattern and replaced with the corresponding pattern.
[0019]
The above encryption process will be described with reference to FIG. FIG. 3 is a block diagram of the encryption process, 10 is a memory for storing a digital original image signal serially input from the terminal 10G, and 20 is a pixel to be encrypted in the image input by the terminal 20P. 30 receives a signal indicating one pixel or block pixel from a memory 41, which will be described later, and reads a pixel at a specified position in the memory 20 from the memory 10 in units of one pixel or block pixel. This is an encryption position collation unit that collates pixel data to be encrypted.
[0020]
Reference numeral 41 denotes a memory for holding an encryption type instruction signal input from the terminal 41T. The encryption type designates a single pixel or a block pixel, and “addition” processing is performed for each pixel. Or “replacement” processing, and in the case of “replacement” processing, the replacement pattern is instructed and input. Reference numeral 42 denotes a pattern table for replacement of a single pixel or block pixel selected by the instruction signal read from the memory 41 when the above replacement processing is instructed.
[0021]
Next, reference numeral 43 denotes a pattern table search unit which receives an output (single pixel instruction; C // block pixel instruction in FIG. 4; C in FIG. 7) from the position matching unit 30 and receives from the encryption type instruction signal memory 41. According to the read “addition” or “replacement” instruction signal, in the case of an addition instruction, the replacement pattern table 42 (FIG. 5) for each pixel is read out and output to the subsequent encryption processing unit 40. To do.
[0022]
If the encryption is “addition”, the encryption processing unit 40 performs encryption by addition to the pixel at the designated position of the original image, and if the encryption designates “replacement”, the designated position of the original image In the memory 50 (single pixel instruction; C // block pixel instruction in FIG. 4; C in FIG. 7), the encrypted pixel obtained by replacing the above-mentioned pixels by the designated pattern table is stored and transmitted to the receiving end. The encryption type instruction signal 51, the encrypted pixel position signal 53, and the encryption-compatible decryption pixel information 52 (C in FIG. 4 / C in FIG. 7) are transmitted together.
[0023]
Details of the above-described encryption and decryption of the original image will be further described with reference to FIGS.
(1) First, a case where a pixel position is designated by a single pixel will be described.
[0024]
FIG. 4 is an explanatory diagram for specifying a single pixel of an original image pixel to be encrypted. FIG. 4A is an example of a display image, FIG. 4B is an example of pixel numbering, and FIG. FIG. 4 is a memory explanatory diagram of encrypted numbered pixels. The screen in FIG. 6A is composed of, for example, 6 vertical lines with 8 pixels in the line. The positions indicated by “◯” are the individual pixel positions, and “shaded pixels” in the figure are encrypted. It shows that If the encrypted pixel is displayed without being restored at the receiving end, it will be displayed in an encrypted state. For example, if the encryption is set to “white”, the screen of the receiving end will have a “shaded” portion. Is displayed as "blank".
[0025]
This designated pixel position is numbered from the pixel at the upper left corner of the screen toward the lower right corner as shown in FIG. 5B, and is, for example, “00” to “47” for 48 pixels. Therefore, the numbering of the “shaded pixels” position in FIG. 6A is “25” to “30”, and the arrangement in the memory is stored in one vertical column as shown in FIG. Yes.
[0026]
3 forms the “presence / absence” column, the “numbering” column, and the “pixel information (X, Y, Z)” column of the original image. In the “numbering” column of this figure (C), “O” marks are assigned to the “presence / absence” columns of “25” to “30” as symbols indicating the numbering target. Note that the inside of the chain line frame in FIG. 8C indicates the encryption processing target, the position line 53 in the “numbering” column is the position signal 53, and the inside of the chain line frame in the “original image pixel information” column is the encryption. Encrypted decryption pixel information 52 and a chain line frame in the “encrypted image pixel information” column show an encrypted pixel pattern 54, respectively.
[0027]
Next, for example, if the instruction input from the terminal 41T is “addition”, the encryption processing unit 40 uses the input or preset constant (α) as the pixel of the original image at the designated position (25-30). The information is added to each of the information (X, Y, Z), and the result is encrypted in the chain line frame of FIG. (C) of the pixel information (X / L, Y / L, Z / L) of the encrypted image in the same row. The pixel pattern 54 is stored, and the information of the original image is copied and stored as it is for the pixels at other positions.
[0028]
When the instruction input from the terminal 41T is “replacement” and “pattern (1)”, the pattern table 421 shown in FIG. 5 is selected. If each of the three elements of the pixel is an 8-bit pattern, the “original image pattern” field of the pattern table 421 is searched for each element, and when the corresponding pattern is searched, the pattern “ Select “LLLLLLLL” to replace. (Encrypted pixel pattern 54 in the chain line frame in FIG. 4)
Here, the pattern “LL to L” means any combination of bit patterns. When the encryption process is to be “white”, it is set to “00 to 0” or “black” is desired. Is set to “11 to 1”, and each of the three elements (X, Y, Z) for one pixel may be replaced with the above pattern.
[0029]
Alternatively, when all the designated position pixels are to be “pure red”, the three elements X, Y, and Z of the pixels are set to three primary colors (red = R, green = G, blue = B), and a replacement pattern for R In this case, the pattern table is “11 to 1”, and the replacement pattern for other G and B may be a table in which the pattern table is set to “00 to 0”.
[0030]
Alternatively, when it is desired to make the encryption in which the state of the encrypted pixel is adjusted at the “luminance” level, the three elements of the pixel are set to a signal (y, u, v) based on the luminance and the hue, and the level is set for the luminance y. A pattern table to be adjusted may be set in FIG.
[0031]
As described above, the original image is encrypted on a pixel-by-pixel basis, and as shown in FIG. 4C, “O” is marked in the “Presence” column corresponding to “25” to “30” in the “Numbering” column. The pixel information (X / L, Y / L, Z / L) obtained by encrypting the pixel elements (X, Y, Z) in the same row is stored. That is, the “encrypted image pixel information” in the right column of FIG. 4C is stored in the encrypted image memory 50 in FIG. 3, and an encryption type instruction signal (for example, an addition instruction) is transmitted to the receiving end. , Constant α, or replacement instruction and pattern table number) 51, an encryption-designated position signal 53, and encryption-compatible decryption pixel information 52 are transmitted together.
[0032]
Next, processing at the time of decryption when an encrypted image is received by designating a single pixel will be described.
FIG. 6 is a decoding process block diagram corresponding to the process block diagram of FIG. In the figure, the same reference numerals as those used in FIG. 3 indicate the same thing, 60 is a pixel reading unit to be decoded, 73 is a decoding pattern search unit, 70 is a decoding processing unit, and 80 is a decoded image display. Part.
[0033]
The operation of the decoding process having the above configuration will be described below.
The encrypted image data (right column of C in FIG. 4; “pixel information of the encrypted image”) is received by the encrypted image memory 50 as described above. In addition, an encryption type instruction signal 51, a position signal 53, and encryption-compatible decryption pixel information 52 are also received.
[0034]
The decryption pixel reading unit 60 confirms that the encryption pixel designation from the encryption type instruction signal 51 is designated in units of one pixel, and the pixel information (X / L, (Y / L, Z / L) are sequentially output to the subsequent decoding pattern search unit 73 while adding numbers to the last line while reading one line at a time.
[0035]
The decryption pattern search unit 73 that has received the output for each line determines from the encryption type instruction signal 51 whether the encryption is “addition” or “replacement”. And reading the number (C in FIG. 4) from the position signal 53.
[0036]
Next, the decryption pattern search unit 73 collates the numbering for the input pixel signals (X / L, Y / L, Z / L) for one line, and if the line is not an encryption target line, the decryption process is performed as it is. The unit 70 is passed through and sent to the display unit 80. On the other hand, when it is determined that the line is an encryption target line, the encrypted pixel signal (X / L, Y / L, Z / L) for one line is output to the decryption processing unit 70.
[0037]
The decryption processing unit 70 receives this pixel information (X / L, Y / L, Z / L) and subtracts each of the encrypted pixels (X / L, Y / L, Z / L) by a constant α. Are decoded and output to the display unit 80 in the subsequent stage.
[0038]
On the other hand, the decryption pattern search unit 73 that has received the output for each line determines from the encryption type instruction signal 51 that the encryption is “replacement” and has been processed by the replacement pattern (1) 421. Therefore, the number of the replacement position (C in FIG. 4) is read from the position signal 53.
[0039]
Next, the decryption pattern search unit 73 collates the numbering for the input pixel signals (X / L, Y / L, Z / L) for one line, and if the line is not an encryption target line, the decryption process is performed as it is. The unit 70 is passed through and sent to the display unit 80. On the other hand, when it is determined that the line is an encryption target line, the original pixel (X, Y, Z) for one line is read from the encryption corresponding decryption pixel information 52, and the pixel for one line that is encrypted is read. It outputs to the decoding process part 70 with a signal (X / L, Y / L, Z / L).
[0040]
The decryption processing unit 70 receives these signals (X, Y, Z; X / L, Y / L, Z / L) and generates the encrypted pixels (X / L, Y / L, Z / L) as the original. The pixel (X, Y, Z) is replaced and decoded and output to the display unit 80 at the subsequent stage.
[0041]
By performing the above-described decryption process on the received image for each screen, the image encrypted for each pixel is restored and displayed.
In the above embodiment, the pixel before encryption of the original image is sent to the decryption side as the encryption-compatible decryption pixel information 52, but pixel information other than the pixels of the original image may be sent. I can do it. For example, the original image is a full color of 16.77 million colors, and the encryption is replaced with 16 colors and sent out. Decoding pixels are changed according to the fee structure, and the decoding is made according to the amount paid by the viewer. Pixels can be selected and sent out from “full color”, “32K colors”, “256 colors”, etc., and the decoded images can be displayed with different image quality.
[0042]
The above-mentioned encryption / decryption process may be transmitted / received for each screen if the target document is a still document, but if the target document is a moving image, it is per screen for all images in one frame. Will be processed.
[0043]
The process in FIG. 6 is for decrypting an encrypted image. However, since the received image is not necessarily decrypted, a determination unit for determining whether or not to decrypt is provided in the previous stage. The received document can be displayed as encrypted without being decrypted, and when the viewer wishes to view the document, the decryption process can be performed.
[0044]
As described above, in the embodiment of the present invention, the pixel to be encrypted is designated for each pixel, but the pixel position designation means on the display screen uses a technique well-known in the image processing system application. Specify. For example, a desired image position is moved within the screen by enlarging and scrolling the display screen, and the position of each pixel is changed with a numeric keypad of the keyboard or a pointing device (mouse, trackball, etc.) by increasing the magnification at this time. This command is used to capture the designated position coordinates. Or you may open the movable window which raised the magnification on the screen by the technique generally known as a loupe.
(2) Next, a case where a pixel position is designated by a block pixel will be described. Since the block designation is different only in the extraction position of the encryption from the pixel designation, the feature point of this operation will be described in the case where the encryption is “replacement”.
[0045]
As a means for designating a block, numbering is performed for every N × M pixels adjacent to each other on the screen, and an arbitrary plurality of blocks are input to the numbered position using a numeric keypad of the keyboard, or Using the keyboard cursor movement key or mouse cursor dragging for frame outline designation, or the mask function of the scanner, etc., the block is instructed on the screen.
[0046]
FIG. 7 is an explanatory diagram of designation of original image pixels to be encrypted in a block, where FIG. 7A is a 2 × 2 block diagram, FIG. 7B is a block numbering diagram, and FIG. FIG. 3C is a memory explanatory diagram of the encrypted numbered pixels. The screen in FIG. 6A is composed of, for example, 6 vertical lines with 8 pixels in the line, the positions indicated by “◯” are the individual pixel positions, and the four pixels in the chain line frame are one block. In the figure, “shaded blocks” are encrypted. When the encrypted block pixel is displayed without being restored at the receiving end, it is displayed in the encrypted state in the same manner as when instructed in units of pixels.
[0047]
This block pixel designation position is numbered from the pixel at the upper left corner of the screen toward the lower right corner, as shown in FIG. 5B, for example, from “0” to “7” for 8 block pixels. Therefore, the numbering of the “shaded block” position in the figure (A) is “1”, and the arrangement in the memory is four places in one vertical column as shown by the chain line frame in the figure (C). Are distributed and stored. In FIG. 6C, “Ad” at the left end is an in-memory address, and “BNo.” Is a block numbering.
[0048]
Then, the encryption position verification unit 30 shown in FIG. 3 determines that the encryption is instructed by a block according to the instruction from the encryption type instruction signal memory 41, and “Ad” in FIG. Column, “BNo.” Column, and “original image pixel information (X, Y, Z)” column are formed, and “1” in the “BNo.” Column of FIG. “○” mark is given as a symbol meaning the object.
[0049]
Subsequently, the pattern table search block 43 uses the table shown in FIG. 8 to encrypt the block pixel at the designated position.
FIG. 8 is a block diagram of a 2 × 2 block pixel replacement pattern table, which is an encryption composition pattern. In this example, a four-column table (421-1, 421-2, ..., 421-n) is used for one block. In the figure, the first column corresponds to the upper left corner of the block pixel, the second column corresponds to the upper right corner, the third column corresponds to the lower left corner, and the fourth column corresponds to the lower right corner. When the block number is 1 and the pattern 2 is specified, the address in memory “02, 03, 10, 11” becomes the replacement target, and the replacement pattern (2) 421-2 is applied.
[0050]
For example, when “filled square” is being displayed on the pixel at this time and the encryption is set to “filled triangle”, BNo. = 1, the first column of “MMM to M” 421-2 in the replacement pattern column is set to “00 to 0”, and the second column to the fourth column are set to “11 to 1”.
[0051]
The pattern table search unit 43 in FIG. 3 performs the BNo. Corresponding to Ad = 02, 03, 10, 11 in FIG. Is assigned number = 1, the pattern table (2) 421-2 in FIG. 8 is searched and output to the encryption processing unit 40 at the subsequent stage.
[0052]
In response to this output, the encryption processing unit 40 sets the replacement pattern (2) at the corresponding position of the pixel information (X / M, Y / M, Z / M) of the encrypted image in the right column of FIG. BNo. Read and replace “MMM to MM” in the row of = 1.
[0053]
The block pixel encrypted as described above is transferred to the decryption side, but the transfer information and the processing process on the decryption side at this time are the same as the single pixel designation, and the subsequent description is omitted.
[0054]
【The invention's effect】
As described above in detail, the application of the technology for encryption in units of pixels or block pixels of the present invention has a great effect that it can be used in the CATV system, VDO system, or education field.
[0055]
By applying the present invention, the charge system can be changed from the conventional fixed amount method to the charge method by limiting the charge system to only one screen of a document including a portion obtained by decrypting the encrypted portion.
[0056]
This eliminates the need for the information provider to determine the price of the product (provided program) with a uniform amount of money, and in particular for a program that includes a document with a high commercial value as one scene It has a special effect that can be sold and sold.
[0057]
Also, viewers do not need to be charged a vague and uniform fee for each program, and meet the demand at the appropriate price for the product (literature or one scene in the program) that they wish to view or obtain. Has a special effect that can.
[0058]
In addition, the information provider has an effect that the price for the same document can be set corresponding to the resolution of decoding.
This is because the definition in this case can be adjusted by brightness / luminance / hue for the decoded image by selecting factors such as RGB / yuv / HVS as factors for setting the pixel elements of the original image.
[0059]
Also, by performing encryption in block pixel units, the “curve” that composes the image can be “straightened”, or the original “kanji” part can be “hiragana” and restored in response to requests from the decryption side. There is an extraordinary effect that allows an operation to bring the state closer to the original image step by step.
[Brief description of the drawings]
FIG. 1 is a principle diagram of the present invention.
FIG. 2 is a control procedure diagram of encryption / decryption.
FIG. 3 is a block diagram of encryption processing.
FIG. 4 is an explanatory diagram of designation of original image pixels to be encrypted.
FIG. 5 is a configuration diagram of a replacement pattern table for each pixel.
FIG. 6 is a block diagram of decoding processing.
FIG. 7 is an explanatory diagram of designation of original image pixels to be encrypted in a block.
FIG. 8 is a block pixel replacement pattern table configuration diagram.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Original document storage means 2 Numbering means 3 Encryption target pixel reading means 4 Action means 5 Encrypted document storage means 6 Decoding target pixel reading means 7 Restoration means 8 Display means 10 Original image memory 20 Position signal memory 30 Encryption position matching unit 40 Encryption processing unit 41 Encryption type instruction signal memory 42 Replacement pattern table 43 Pattern table search unit 50 Encrypted image memory

Claims (7)

In a document encryption apparatus that arranges a plurality of pixels and displays the document information expressed by chain expansion or localization of the color information of each of the plurality of pixels,
And the original document storage means for storing as pixels of a two-dimensional array of when it is displayed a plurality of pixels on a screen constituting the original document, numbering means for specifying the position of a pixel to be encrypted is subjected to the numbering in the pixel Reading means for reading the numbered pixels designated by the numbering means, action means for encrypting by applying an operator to one or more factors constituting the read pixels, Encryption storage means for storing document information specifying the position of the selected pixel,
The pixel is composed of a plurality of numerical factors, and the operator acting on the factor is an arithmetic operator, and the encryption storage means decrypts overflow or underflow caused by the operation of the operator in encryption. An apparatus for encrypting a document, characterized in that the pixel at a designated position of the original document image information is encrypted so as to be sometimes compensated. In a document decoding apparatus that arranges a plurality of pixels and displays document information expressed by chain expansion or localization of color information of each of the plurality of pixels,
Storage means for storing the encrypted document information, reading means for reading out the encrypted pixel from the document information, and restoration means for returning the operation of the operator from the encrypted pixel,
When the restoration means decrypts the pixel encrypted by the substitution by the substitution table, the restoration unit receives the encryption pixel and the pixel position for diminishing the encryption effect together with the encrypted pixel, and reduces the encrypted pixel to the diminishing pixel. A document decryption apparatus, wherein a pixel at a designated position in encrypted document information is decrypted and displayed on a display means by replacing with a pixel for use. 2. The document encryption apparatus according to claim 1, wherein the encryption target is designated for each block including a single pixel and / or a plurality of pixels. 3. The document according to claim 2, wherein the encrypted pixel is a single pixel and / or a pixel at a designated position in the document information processed by a block in which a plurality of pixels are combined. Decoding device. The pixel is composed of a plurality of numerical factors, and has a replacement table for replacing the numerical pattern formed by the factor at the encryption designated position of the original pixel with a different numerical pattern, and the operator stores the factor in the replacement table. 2. The document encrypting apparatus according to claim 1, wherein the encrypting apparatus operates so as to replace with a pattern selected from the above. The replacement table according to claim 5 is a table provided corresponding to the three primary colors of light or luminance / hue, or hue / lightness / saturation for each factor in the state where the original pixels are described with three factors. A document encryption apparatus characterized by being. The decryption of a document according to claim 2 or 4, wherein when decrypting a pixel encrypted by the replacement by the replacement table, information on the original pixel and a pixel position are received together with the encrypted pixel. Device.

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