JP3881733B2 - Confidential information recording method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, confidential information is recorded on a print medium such as a sheet of paper together with appropriate public information so that the existence of the confidential information is not known to a third party, and can be reproduced as necessary. The present invention relates to a method for recording confidential information.
[0002]
[Prior art]
As a method for concealing and recording confidential information on paper, a method of printing required confidential information on paper with a special transparent paint is known. However, this method makes it difficult to produce special ink, which increases the cost, and its chemical properties deteriorate with the passage of time, so the storage stability is poor and copying using a copying machine is impossible. There are problems such as being unable to meet the demand for a large amount of duplication.
[0003]
In order to improve such drawbacks, a method of embedding confidential information codes by shifting specific positions of dots (pixels) constituting characters and numbers printed on paper (Japanese Patent Laid-Open No. 60-48586). In the facsimile transmission document, the number of pixels of the scanning line is changed according to a predetermined rule, whereby the signature text is embedded in the facsimile image data, and the document in which the signature text is embedded in this way is scrambled. A transmission method (Japanese Patent Laid-Open No. 5-37795) is known.
[0004]
[Problems to be solved by the invention]
However, since these known methods change the position of the pixels of the public information to be printed on a print medium such as paper, or change the number of pixels on the scanning line, in any case, there is confidential information. The amount of information that can be embedded depends on the state of the embedded image, and there is a problem that a large amount of confidential information cannot be recorded.
[0005]
An object of the present invention is to record confidential information of a desired amount of information on a print medium without being noticed by a third party regardless of the number of pixels of public information to be printed on the print medium. It is to provide a method of recording confidential information that can be performed.
[0006]
The present invention also provides a confidential information recording method that does not require a special printing device for printing an image in which confidential information is embedded, and does not require a special reproducing device for decoding the image. There is.
It is another object of the present invention to provide a confidential information recording method capable of preventing the confidential information from being decoded from the image data in which the confidential information is embedded even if the playback device is transferred to a third party. is there.
[0007]
[Means for Solving the Problems]
A feature of the invention described in claim 1 for solving the above problem is a confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a reference point code obtained by encoding a reference point mark in the dotted public information data to obtain reference information data;
Embedding a predetermined position determination code in the reference information data at a position according to the contents of a plurality of data blocks corresponding to the reference point code embedded in the reference information data;
Creating print data according to the composite information data;
Printing an image according to the composite information data on a print medium according to the print data;
It is in the point including.
[0008]
The feature of the invention described in claim 2 for solving the above problem is a confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a reference point code obtained by encoding a reference point mark in the dotted public information data to obtain reference information data;
Embedding a predetermined position determination code in the reference information data at a position according to the content of the data block corresponding to the reference point code embedded in the reference information data, and creating composite information data;
Creating print data according to the composite information data;
Printing an image according to the composite information data on a print medium according to the print data;
It is in the point including.
[0009]
The feature of the invention described in claim 3 for solving the above problem is a confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a reference point code obtained by encoding a reference point mark in the dotted public information data to obtain reference information data;
A position determination code according to the content of the other data block is added to the position according to the content of one data block of the two data blocks corresponding to the reference point code embedded in the reference information data. Creating composite information data by embedding it in the data;
Creating print data according to the composite information data;
Printing an image according to the composite information data on a print medium according to the print data;
It is in the point including.
[0010]
A feature of the invention described in claim 4 for solving the above problem is a confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a reference point code obtained by encoding a reference point mark in the dotted public information data to obtain reference information data;
The position determination code according to the contents of the remaining data blocks is added to the position according to the contents of any two data blocks of the three data blocks corresponding to the reference point code embedded in the reference information data. Creating composite information data by embedding in reference information data;
Creating print data according to the composite information data;
Printing an image according to the composite information data on a print medium according to the print data;
It is in the point including.
[0011]
A feature of the invention described in claim 5 for solving the above problem is a confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a reference point code obtained by encoding a reference point mark in the dotted public information data to obtain reference information data;
A set corresponding to the reference point code embedded in the reference information data is in accordance with the contents of two sets of data blocks consisting of two data blocks, and the position specific to the set at a position according to the contents of each set of data blocks Embedding a discrimination code in the reference information data to create composite information data;
Creating print data according to the composite information data;
Printing an image according to the composite information data on a print medium according to the print data;
It is in the point including.
[0012]
In any configuration, the blocked data obtained by arbitrarily dividing the binarized confidential information data may be rearranged by the encryption key.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a diagram for explaining an example of an embodiment of the invention of claim 1 in which required confidential information is encoded and a public information image is printed on a print medium on which a third party cannot know the presence. It is a flowchart which shows the preparation method of the confidential information recording document made to record using a small dot pattern. The method for creating a confidential information recording document shown in the flowchart of FIG. 1 is a method of combining information as a distance value from a reference point on a public information image. Necessary confidential information is binarized and blocked to an arbitrary size, and the blocked confidential information is converted into an analog value. For example, black dots or black and white combination dots at positions corresponding to the respective analog values in the vertical and horizontal directions from the reference point on the public information image using a set of two pieces of information converted into analog information Arrange the pattern. Thereby, the number of dot codes to be embedded can be reduced as compared with the case where all confidential information is embedded as dot codes. However, it is desirable that the dot pattern has a resolution of 400 dpi or more and a pattern arrangement density of 1% or less, for example, so that the recorded position cannot be detected by human eyes. In addition, the said dot pattern is not limited to the combination of 2 colors of black and white, Arbitrary color dots can be used, For example, 2 colors, such as red and white, may be sufficient.
[0015]
The method will be described in detail below with reference to the flowchart of FIG. 1. In step 11, first, the required confidential information is binarized to obtain binary confidential information data. This confidential information may be image data, computer program data, audio data, or musical tone data in addition to character data. In the next step 12, the binarized confidential information data obtained in step 11 is blocked into an appropriate size. In the example shown in the figure, the block size is 8 bits. However, this is an example, and an arbitrary size may be used. In step 13, an encryption key is determined. This encryption key includes an encryption code indicating a rule for rearranging the blocks of the binarized confidential information data created in step 12, and configures the binarized confidential information data obtained in step 12 according to this code. Rearrangement of a plurality of blocks (n blocks in the present embodiment) is executed in step 14, whereby confidential information blocks B1, B2, B3,..., Bn are obtained as dot data. For the encryption here, for example, a conventional encryption system or a public key encryption system can be used. Depending on the amount of confidential information, the number of confidential information blocks is usually several thousand blocks, and the confidential information block includes several thousand confidential information blocks. When the number of bits of the last confidential information block Bn obtained by dividing the binarized confidential information data into a predetermined bit size is smaller than the predetermined bit size, “0” corresponding to the insufficient number of bits. Are added to the end to obtain a predetermined bit size. In the next step 15, each dot data of the confidential information block obtained in step 14 is converted into a decimal number.
[0016]
Next, in step 16, the imaged public information image such as a sentence or a picture that is to be printed on paper is converted into dots, thereby obtaining dotized public information data. This dot release public information data is binarized data according to a dot pattern indicating the pixel arrangement of the public information image. In the next step 17, N (= [(n + 1) / 2]) reference point codes are dot-released for the number n of confidential information blocks B 1, B 2,..., Bn obtained in step 15. Embed by replacement in information data. When n is an odd number, “0” for one block is added to the end of the binarized confidential information data, that is, (00000000), and the (n + 1) th confidential information block is prepared in advance. Make sure that the number of is even.
[0017]
The creation of the reference information data in step 17 is performed as follows. First, in the first execution of step 17, a process of embedding the reference point code corresponding to the confidential information block B1 by replacing it with the dotized public information data is executed, thereby obtaining the reference information data. When the above-described series of data processing in step 17 is completed, step 17 is executed again, and the reference point code corresponding to the confidential information block B2 is embedded in the previously obtained reference information data. In this manner, the reference information data obtained in step 17 is used as updated dot-open public information data in the subsequent processing in step 17. The above-described processing in step 17 is repeatedly executed L (= N) times according to the number of confidential information blocks obtained previously.
[0018]
The reference point code is a reference point mark for indicating a reference point on the printed paper and limits the embedding direction and order (vertical and horizontal) of dot data in the confidential information block, and may be a fixed value. However, it may be uniquely given by an encryption key. It is preferable to print at least one mark having asymmetry for distinguishing the upper, lower, left and right sides of the sheet on the sheet, but at least one of the reference point marks is an asymmetry necessary for this type of discrimination. It is good also as the mark which gave the property.
[0019]
In step 18, a process for embedding the contents of the confidential information blocks B1, B2, B3,..., Bn in the reference information data obtained in step 17 is executed.
[0020]
The processing for embedding the confidential information data is performed by using two consecutive decimal number data corresponding to each reference point code from the position of the reference point code embedded in the reference information data, that is, two consecutive confidential information blocks. This is a processing step for creating composite information data by embedding predetermined position determination codes by replacement at positions separated according to the contents. The reference point code and the position determination code may be fixed values or may be uniquely determined by an encryption key.
[0021]
In the case of the embodiment shown in FIG. 1, two consecutive confidential information blocks (B1, B2), (B3, B4),... Become one set and each set from the corresponding reference point code. A predetermined position determination code for position determination is embedded in the reference information data at a position separated by a distance indicated by the decimal data of the confidential information block, thereby obtaining composite information data. If n is an odd number, the confidential information block B _2N Is processed as (0). Accordingly, in the final reference information data, the reference point codes of the number (N) that is ½ of the number of confidential information blocks obtained in step 15 are embedded.
[0022]
Here, the reference point code is defined as (101010), and pixel data for printing is printed by a printer having a resolution of about 400 dpi or higher as will be described later. Therefore, the reference point pattern (reference point mark) printed on the paper surface by the reference point code is extremely small and it is impossible to visually determine its presence, and a reference point mark printed on the paper by a third party. You will not notice the existence of. The same applies to the position determination mark. Since the embedding area of the reference point code and the position determination code is very small, the public information image in which these codes are embedded is the same as the original public information image, and confidential information is embedded in this public information image. It is not possible to determine just by visual inspection.
[0023]
Specifically, first, the decimal data (174) of the first confidential information block B1 obtained in step 15 and the decimal data (56) of the second confidential information block B2 are obtained. It is taken in as two decimal data in units of two consecutive blocks corresponding to the first reference point code. The contents of these decimal data are 174 and 56, and a predetermined position determination code (110011) is located at a position away from the position of the first reference point code already embedded in step 17 according to these values. It is embedded by replacement with the reference information data at that position.
[0024]
This will be described in more detail with reference to FIG. 2 in the case of the present embodiment. “1” and “0” arranged vertically and horizontally in FIG. 2A are codes indicating the contents of each pixel of the dotized public information data, and the portion (101010) is the first reference point code. Is where it is embedded. Now, a position determination code (110011) is embedded at a position corresponding to a value of 174 and a value of 56 with reference to the position of the first reference point code. This embedding rule is 174 bits apart from the first bit position of the first reference point code in the horizontal positive (+) direction, and the vertical direction from the first bit position of the first reference point data. The bit positions that are separated by 56 bits in the negative (-) direction are embedded by replacement along the horizontal direction so as to be the position of the first bit of the position determination code (110011).
[0025]
In this way, a predetermined position determination code is embedded by replacement at a position representing the contents of the confidential information blocks B1 and B2 in relation to the reference point code of the first position. Thereafter, a predetermined position determination code is embedded by substitution in the same procedure at a position representing the contents of the second set of confidential information blocks B3 and B4 in relation to the reference point code at the second position.
[0026]
That is, the confidential information block B that is the Nth set in relation to the reference point code of the Nth position _2N-1 , B _2N Step 18 is repeatedly executed L (= N) times until the position determination code representing the content of is embedded in the reference information data by replacement.
[0027]
In this way, in step 18, the above-described embedding by replacing the position determination code according to the number of confidential information blocks prepared in step 15 is performed on the plurality of reference point codes embedded in the reference information data. Run repeatedly. A position determination code is embedded at a position indicating each content of the confidential information block data in the reference information data to obtain composite information data. As can be understood from the above description, the combined information data obtained in step 18 is treated as updated reference information data in the confidential information block embedding process in step 18 which is repeated immediately after that. It will be.
[0028]
FIGS. 2B and 2C show an enlarged example of a dot pattern when the reference point mark and the position determination mark are actually embedded by replacement. FIG. 2B shows an example in which the values of one set of confidential information blocks are both zero. As can be seen from FIG. 2B, the dot (pixel) difference between the reference point mark R1 and the position determination mark D1 is zero in both the vertical and horizontal directions. FIG. 2C shows an example in which the values of one set of confidential information blocks are 2 and 3. In the case of FIG. 2C, the dot (pixel) difference between the reference point mark R2 and the position determination mark D2 is 2 in the horizontal direction and 3 in the vertical direction.
[0029]
In step 19, print data that is dot-patterned according to the composite information data finally obtained in step 18 is created, and printing of public information in which confidential information is embedded is executed according to this print data. As described above, this printing can be performed using a printing machine that digitally prints pixel data having a resolution of about 400 dpi or higher, for example, a laser printer.
[0030]
As can be seen from the above description, each of these marks is considered to be very small and its arrangement density is 1% or less, so that these marks are printed by replacement in the public information image by visual inspection. It is impossible to determine whether or not there is any confidential information. Further, as can be easily understood from the above description, the position information of the position determination code of the position determination mark corresponds to the bit information of two confidential information blocks, and even if there is a blank portion in the public information image. The amount of information that can be embedded can be extremely large compared to the conventional method of shifting the position of the pixel data of public information due to the availability. Therefore, for example, image data, computer program data, audio data, or musical tone data can be embedded by this method. Furthermore, it is possible to copy a large amount of the same thing by copying, and it is possible to send it far away by a facsimile machine.
[0031]
In order to reproduce the confidential information based on the confidential information recording document in which the confidential information is embedded in this way, for example, image information on the paper surface by an image scanner provided in a document reading unit such as a copying machine. Are detected in units of pixels, and based on the data read in units of pixels, the respective reference point marks (codes) and the position determination marks (codes) embedded corresponding to these are detected. Then, the contents of the confidential information block can be reproduced from the positional relationship between the reference point code and the corresponding position determination code. When the contents of all the confidential information blocks have been reproduced in this way, the reverse of the rearrangement of the confidential information blocks in step 14 is performed using the restoration key paired with the predetermined encryption key, By converting the decimal number of the confidential information block into a binary number, the state of the binarized confidential information data in step 11 can be restored. Based on this binarized confidential information data, it is possible to easily obtain confidential information in a desired expression form. Therefore, no special playback device is required for the playback.
[0032]
In the embodiment shown in FIG. 1, the confidential information blocks are rearranged in accordance with the encryption key in step 14, but this procedure can be omitted. When step 14 is omitted in the embodiment shown in FIG. 1, it is not necessary to reversely sort the confidential information blocks when reproducing the confidential information.
[0033]
In the example of the embodiment of the invention of claim 1 described based on FIG. 1 and FIG. 2, two confidential information blocks are assigned to one reference point mark, and the positional relationship with the reference point mark according to these contents In order to print the position determination mark. However, a configuration in which three or more confidential information blocks are allocated to determine the positional relationship is also possible. In any case, the reference point mark and the position determination mark can be an appropriate pattern based on color dot information in addition to a mark based on black and white dots. The public information may be either black and white or color.
[0034]
Next, an example of an embodiment of the invention of claim 2 will be described with reference to FIGS. The creation of the confidential information recording document by applying the invention of claim 2 is the same as the process of FIG. 1 shown for the embodiment of the invention of claim 1 except for the processing contents of steps 17 and 18 shown in FIG. Therefore, FIG. 3 shows only steps 27 and 28 corresponding to steps 17 and 18, and the other steps are not shown, and will be described with reference to FIG. 1 as necessary.
[0035]
As in the case of step 17, in step 27, embedding is performed in the dotized public information data by replacing the reference point code. By repeatedly executing step 27, the same number of reference point codes as the number of confidential information blocks B1, B2,..., Bn obtained in step 15 are sequentially embedded in the dotized public information data.
[0036]
The creation of reference information data in step 27 is performed as follows. First, in the first execution of step 27, a process of embedding the reference point code corresponding to the confidential information block B1 by replacing it with the dotized public information data is executed, thereby obtaining the reference information data. When the above-described series of data processing in step 27 is completed, step 27 is executed again, and the reference point code corresponding to the confidential information block B2 is embedded into the previously obtained reference information data. In this way, the reference information data obtained in step 27 is used as updated dot-open public information data in the subsequent processing of step 27. The above-described processing in step 27 is repeatedly executed L (= N) times according to the number of confidential information blocks obtained previously.
[0037]
The reference point code is a reference point mark for indicating a reference point on the printed paper and limits the embedding direction and order (vertical and horizontal) of dot data in the confidential information block, and may be a fixed value. However, it may be uniquely given by an encryption key. It is preferable to print at least one mark having asymmetry for distinguishing the upper, lower, left and right sides of the sheet on the sheet, but at least one of the reference point marks is an asymmetry necessary for this type of discrimination. It is good also as the mark which gave the property.
[0038]
In step 28, confidential information data embedding processing for embedding the contents of the confidential information blocks B1, B2, B3,..., Bn in the reference information data finally obtained in step 27 is executed.
[0039]
This confidential information data embedding process is performed by determining a predetermined position at a position away from the position of the reference point code embedded in the reference information data according to the content of the decimal data of the confidential information block corresponding to each reference point code. The process of creating the composite information data by embedding the codes by replacement is repeated L times as in the case of step 18. In this case, L = n. The reference point code and the position determination code may be fixed values or may be uniquely determined by an encryption key.
[0040]
In the case of the embodiment shown in FIG. 3, each confidential information block B1, B2,... Has a predetermined distance from the corresponding reference point code by a distance indicated by the decimal data of the confidential information block. This is a method of embedding a position determination code for a position determination mark by replacement, and the same number of reference point codes as the number of confidential information blocks obtained in step 15 are embedded in the dotted public information data by replacement, whereby reference information Data is obtained.
[0041]
Here, the reference point code is defined as (101010), and the pixel data for printing is printed by a printer having a resolution of about 400 dpi or higher as will be described later. Therefore, the reference point pattern (reference point mark) printed on the paper surface by the reference point code is extremely small and it is impossible to visually determine its presence, and a public information image printed on the paper by a third party. You will never notice the presence of the reference mark inside. The same applies to the position determination mark. Since the embedding area of the reference point code and the position determination code is very small, the public information image in which these codes are embedded is the same as the original public information image, and confidential information is embedded in this public information image. It is not possible to determine just by visual inspection.
[0042]
This will be specifically described with reference to FIG. In FIG. 4A, the decimal data of each confidential information block B1, B2, B3, B4,... Obtained in step 15 is (174), (56), (128), (78). Suppose that ... In the reference information data, reference point codes corresponding to the reference point marks R1, R2, R3, R4,. When step 28 is entered, first, with respect to the first reference point mark R1, the decimal data (174) of the first confidential information block B1 corresponding thereto is referred to, so that the first reference point mark R1. A position determination code corresponding to a predetermined position determination mark D1 is embedded by replacement of data at a position advanced by 174 bits in the horizontal (+) direction. 4A schematically shows the printed state unlike FIG. 2A, the data embedding method itself is essentially the same as that shown in FIG. There is no change.
[0043]
In this way, the decimal data (56) of the second and subsequent confidential information blocks B2, B3, B4,... With respect to the second and subsequent reference point marks R2, R3, R4,. , (128), (78)... Are associated with each other in the same manner, and in the reference information data, the position is advanced in the lateral positive (+) direction by the number of bits indicated by the decimal data. A required position determination code is embedded by replacement to create composite information data. Therefore, the distance of each position determination mark from the corresponding reference point mark indicates the content of the confidential information block. FIG. 4B shows an enlarged view of the dot pattern when the reference point mark data and the position determination mark data are actually embedded in the reference information data by replacement. In this example, the confidential information block value is zero. As can be seen from FIG. 2B, the difference in horizontal dots (pixels) between the reference point mark and the position determination mark is zero.
[0044]
In the confidential information recording method described with reference to FIGS. 3 and 4, it is necessary to embed the same number of reference point codes as the number n of confidential information blocks to be recorded in the dotted public information data. It is also possible to embed only one reference point code. It is also possible to embed one reference point mark for a plurality of m confidential information blocks.
With reference to FIG. 5 and FIG. 6, an example of a confidential information recording method when only one reference point code is embedded will be described. FIG. 5 is a diagram for explaining data processing for the method, and only steps 27 ′ and 28 ′ corresponding to steps 27 and 28 of FIG. 3 are shown.
[0045]
In step 27 ′, embedding is performed only once by replacing the reference point code in the dotized public information data to obtain reference information data in which only one reference point code is embedded in the dot public information data, and step 28 ′. to go into.
[0046]
The reference point code is a reference point mark for indicating the reference point on the printed paper, and limits the embedding direction and order (vertical and horizontal) of the dot data of the confidential information block, and is a fixed value. Alternatively, it may be uniquely given by an encryption key. It is preferable to print at least one mark having asymmetry for distinguishing the upper, lower, left and right sides of the sheet on the sheet, but at least one of the reference point marks is an asymmetry necessary for this type of discrimination. It is good also as the mark which gave the property.
[0047]
In step 28 ′, processing for embedding the contents of the confidential information blocks B1, B2, B3,..., Bn in the reference information data obtained in step 27 ′ is executed. The process for embedding the confidential information data starts with a predetermined position at a position away from the position of one reference point code embedded in the reference information data according to the content of the decimal data of the confidential information block B1. The identification information is embedded by substitution to create composite information data. For the next confidential information block B2, processing for embedding the position determination code at a position away from the position determination code position of the confidential information block B1 according to the content of the decimal data of the confidential information block B2 is performed. That is, with the reference point code as a starting point, a predetermined position determination code is embedded at a distance corresponding to the values of the confidential information blocks B1, B2,. This process is repeated L times. In this case, L = n.
[0048]
This will be specifically described with reference to FIG. Assuming that the reference point mark is RC1, a predetermined position determination mark D1 is embedded at a position that is 174 bits away according to the value of the confidential information block B1 in the horizontal direction. Then, a predetermined position determination mark D2 is embedded at a position away from the position determination mark D1 in the positive direction next to 56 bits according to the value of the confidential information block B2. Similarly, a predetermined position determination mark D3 is embedded at a position separated by 128 bits, and a predetermined position determination mark D4 is embedded at a position separated by 78 bits.
[0049]
In the example shown in FIG. 6A, the position determination mark is embedded along a predetermined direction at intervals corresponding to the number of bits according to the content of the confidential information block, starting from the reference position mark.
[0050]
However, as shown in FIG. 6B, the position determination mark D1 corresponding to the confidential information block B1 is embedded at a position 174 bits away from the reference point mark RC1 in the horizontal direction, and then from the reference point mark RC1. Alternatively, the position determination codes D3, D4,... May be embedded one after another by repeatedly embedding the position determination mark D2 corresponding to the confidential information block B2 from a position that is a predetermined fixed distance KN in the vertical negative direction.
[0051]
Next, an example of an embodiment of the invention of claim 3 will be described with reference to FIGS. The creation of the confidential information recording document to which the invention of claim 3 is applied is the same as that of the embodiment of the invention of claim 1 except for the processing contents of steps 17 and 18 shown in FIG. Shows only steps 37 and 38 corresponding to steps 17 and 18, and the other steps are not shown, and will be described with reference to FIG. 1 as necessary.
[0052]
In step 37, N (= [(n + 1) / 2]) reference point codes are converted into dot public information data for the number n of confidential information blocks B1, B2,..., Bn obtained in step 15. It is sequentially embedded by substitution. When n is an odd number, “0” for one block, that is, (00000000) is added to the end of the binarized confidential information data, and the (n + 1) th confidential information block is prepared in advance. Step 37 is repeatedly executed, and ½ of the number of reference point codes (= N) of the number of confidential information blocks obtained in Step 15 is embedded in the dotted public information data, whereby reference information data is obtained.
[0053]
The creation of the reference information data in step 37 is performed as follows. First, in the first execution of step 37, a process of embedding the reference point code corresponding to the confidential information block B1 by replacing it with dotized public information data is executed, whereby reference information data is obtained. When the above-described series of data processing in step 37 is completed, step 37 is executed again, and the reference point code corresponding to the confidential information block B2 is embedded in the previously obtained reference information data. In this way, the reference information data obtained in step 37 is used as updated dotized public information data in the subsequent processing in step 37. The above-described processing in step 37 is repeatedly executed L (= N) times according to the number of confidential information blocks obtained previously, thereby obtaining necessary reference information data in which N reference point codes are embedded. It is done.
[0054]
The reference point code is a reference point mark for indicating a reference point on the printed paper, and the dot data embedding direction and order (vertical, horizontal) are determined on the printed paper. The reference point mark for indicating the reference point is provided. It is preferable to print at least one mark having asymmetry for distinguishing the upper, lower, left and right sides of the sheet on the sheet, but at least one of the reference point marks is an asymmetry necessary for this type of discrimination. It is good also as the mark which gave the property.
[0055]
In step 38, processing for embedding the contents of the confidential information blocks B1, B2, B3,..., Bn in the reference information data obtained in step 37 is executed.
[0056]
The processing for embedding the confidential information data is performed by one of the two decimal data of the continuous confidential information blocks B1 and B2 corresponding to each reference point code from the position of the reference point code embedded in the reference information data. This is a processing step for creating composite information data by embedding a position determination code determined according to the other content in the reference information data at a position separated by a distance determined according to the content of Therefore, step 38 is also executed repeatedly L (= N) times. In each execution, the reference point code and the position determination code corresponding to two blocks of confidential information blocks may be fixed values or uniquely determined by an encryption key.
[0057]
In the case of the embodiment shown in FIG. 7, two consecutive confidential information blocks (B1, B2), (B3, B4),... The composite information data is created by embedding a position determination code according to the content of the other decimal data in a position separated according to the decimal data of one of the decimal data of the confidential information block. If n is an odd number, B of the confidential information block _2N Is processed as (0). Accordingly, in the final reference information data, the number (N) of reference point codes that is ½ of the number of confidential information blocks obtained in step 15 is embedded.
[0058]
Here, the reference point code is defined as (101010), and the pixel data for printing is printed by a printer having a resolution of about 400 dpi or higher as will be described later. Therefore, the reference point pattern (reference point mark) printed on the paper surface by the reference point code is extremely small and it is impossible to visually determine its presence, and a reference point mark printed on the paper by a third party. You will not notice the existence of. The same applies to the position determination mark. Since the embedding area of the reference point code and the position determination code is very small, the public information image in which these codes are embedded is the same as the original public information image, and confidential information is embedded in this public information image. It is not possible to determine just by visual inspection.
[0059]
This will be specifically described with reference to FIG. In FIG. 8A, the decimal number data of the first confidential information block B1 and the decimal number data of the second confidential information block B2 obtained in step 15 correspond to the first reference point code. It is taken in as two consecutive decimal data. The contents of these decimal data are 174 and 56, and according to these values, the first decimal number from the position of the reference point code corresponding to the first reference point mark R1 already embedded in step 37 is obtained. A position determination code indicating a position determination mark D56 unique to the value 56, which is the content of the decimal data content of the second confidential information block B2, is embedded by replacement at a position 174 bits away according to the data content.
[0060]
FIG. 8A schematically shows this as in the case of FIG. 4A, and is 174 bits horizontally from the first reference point mark R1 by the first reference point code. A unique position determination mark D56 representing the number 56 is printed as a position determination mark for the first set at a position away from the positive (+) direction. FIG. 8B shows an example of the position determination mark when the content of the decimal data is 56, 57, and 58. However, the position determination mark is not limited to these and is arbitrarily determined. Of course, it may be.
[0061]
Although not shown in (A) of FIG. 8, the same applies to the decimal data (128) and (78) of the next second set of confidential information blocks B3 and B4. The distance from the reference point mark is shown, and (78) shows the shape of the position determination mark to be printed there. Note that it is possible to arbitrarily determine which of the decimal data of the two confidential information blocks made as one set is the distance information and which is the mark form information. FIG. 8C shows an enlarged view of the dot pattern when the reference point mark and the position determination mark are actually embedded by replacement. FIG. 8C shows an example in which the values of one set of confidential information blocks are both zero. Here, the difference in the horizontal dots (pixels) between the reference point mark and the position determination mark D0 is zero.
[0062]
Next, an example of the embodiment of the invention of claim 3 in which the position determination mark is embedded as a color dot pattern will be described with reference to FIGS.
[0063]
In the example of the embodiment according to the processing procedure shown in FIG. 9, the content of confidential information is recorded using a color dot pattern of eight colors in a color public information image. When embedding a color dot of the same color at a position overlapping with the color dot of the public information image, the color dot is left as it is. Conversely, when embedding a color dot of a different color, the color dot of the different color is replaced. As a result, a large amount of confidential information can be embedded even when there are few white areas in the color public information image. The method of embedding confidential information data in a color public information image can be freely set by an encryption key. However, in order to prevent humans from visually detecting the position where the color dot pattern according to the confidential information is embedded, it is desirable that the resolution is 400 dpi or higher and the embedded density of confidential information is 1% or lower.
[0064]
Hereinafter, the method will be described with reference to the flowchart of FIG. 9. In step 121, necessary confidential information is first binarized to obtain binarized confidential information data. This confidential information may be image data, computer program data, audio data, or musical tone data in addition to character data. In the next step 122, the binarized confidential information data obtained in step 21 is blocked into a size of (K + q) × J bits to create a large confidential information block. Here, K indicates the number of unit bits for color information conversion determined by the number of color dots used for embedding the binarized confidential information data. For example, when 8 color dots are used, color information conversion is performed in units of 3 bits, so K = 3. When 16 colors are used, color information conversion is performed in units of 4 bits, so K = 4, and 32 colors are converted. When the color information is converted in units of 5 bits, K = 5, and in the case of 64 colors, color information is converted in units of 6 bits, so K = 6. Similarly, q is the number of unit bits indicating the distance from the reference point mark.
[0065]
As can be seen from the above description, in the present embodiment, one confidential information block is composed of (K + q) bits, and is also dot data indicating the contents of the confidential information block. K is the number of unit bits for color information conversion, and q is the number of unit bits for distance information conversion. K + q is also the number of bits of the confidential information block. Specifically, the content of one confidential information block is converted into a decimal number indicating the color of one color dot such as a red dot, a black dot, a white dot,. In order to be able to scramble a plurality of confidential information blocks as a unit, the confidential information large block is divided into (K + q) × J bits so that the plurality of confidential information blocks are included. It is. That is, J indicates the number of confidential information blocks in the confidential information large block. When J = 1, the confidential information large block consists of only one confidential information block. If the number of bits of the last large confidential information block obtained by dividing the binarized confidential information data into blocks of (K + q) × J bits is (K + q) × J bits or less, A bit of “0” is added to the end of the last confidential information large block so that it becomes (K + q) × J bits, and the number of bits of the last confidential information large block is also (K + q) × J bits. As a result, a plurality of large confidential information blocks each having (K + q) × J bits are created.
[0066]
In step 123, an encryption key is determined. This encryption key includes an encryption code indicating a rule for rearranging the large block of confidential information obtained by dividing the binarized confidential information data obtained in step 22 every (K + q) × J bits, and a confidential information area. Includes an encryption code indicating a rule for embedding the reference point code to be embedded, and a rearrangement method is designated in accordance with this. A plurality of confidential information large blocks obtained in step 122 are rearranged in step 124 Is done. For the encryption here, for example, a conventional encryption system or a public key encryption system can be used. Although it depends on the amount of confidential information, it is usually several thousand blocks, and the confidential information block includes several thousand confidential information blocks.
[0067]
In step 125, the binary data of (K + q) × J bits in the confidential information large block is divided into K bits, and the binary data in K bits is deciphered and the color is determined according to the encryption key obtained in step 123. Convert to information. Also, binary data in q-bit units is converted into decimal numbers. In this embodiment, since eight color dots are used, K = 3, and 3-bit binary data is converted into any numerical value from 1 to 8. In this way, BC11 and BC13 converted into decimal numbers in q-bit units containing distance information in the first confidential information large block BC1, and converted into decimal numbers in K-bit units containing color dot information. The converted BC12 and BC14 are obtained in step 25. The same applies to the second, third,... Confidential information large blocks. The color dot color can be expressed arbitrarily as 1 is white, 2 is red, 3 is blue,..., 8 is black. Also, the color setting method using the encryption key is “000” representing 8 as black, “001” representing 3 as blue, “010” representing 2 as red, and “111” representing 1 as white. Such a method can be appropriately employed.
[0068]
Next, in step 126, a color dot public information data DNC1 is created by converting the color public information image such as a non-confidential sentence or picture to be printed on the paper F into color dots. In step 127, confidential information areas corresponding to the number of large blocks of confidential information obtained in step 122 are set. In the case of this embodiment, since the confidential information is composed of three confidential information large blocks, three confidential information areas XC, YC and ZC are set.
[0069]
In step 128, the same reference point codes as the number J of confidential information blocks in the large confidential information block are embedded in one confidential information area according to the encryption key so as not to overlap. First, a color reference point code DRC1 indicating a reference point mark is prepared, and the reference point code DRC1 is a reference of the confidential information area XC with respect to the dot-formed public information data DNC1 which is a color dot containing the public information image GC. The reference information data DSC1 is generated by combining the first reference point mark RC1 of the color for indicating the position. Therefore, the content of the reference information data DSC1 is obtained by adding the reference point mark RC1 (by the reference point code DRC1 embedded by replacement) to the public information image GC.
[0070]
Next, the process of embedding the second reference point code DRC2 in the confidential information area XC is executed again. The dotted public information data DNC1 in which the reference point code DRC2 is embedded in this case is the reference information data DSC1 updated by the immediately preceding process. In this embodiment, the same number of reference point codes as the number of confidential information blocks in the large confidential information block is embedded in one confidential information area according to the encryption key by replacement. As a result, reference information data DSC1 in which two reference point codes RC1 and RC2 are embedded is created. In this way, the reference information data DSC1 obtained in step 128 is used as updated dotized public information data DNC1 in the subsequent repetitive processing of step 128, and the above-described processing in step 128 is obtained first. The process is repeatedly executed as many times as the number of confidential information areas (three in this embodiment).
[0071]
As a result, final reference information data DSC1 in which the reference point marks RC1, RC2, RC3, RC4, RC5, RC6 are respectively embedded in the three confidential information areas XC, YC, ZC is created, and the next step 129 is performed. enter. Note that the number of repetitions L of step 128 is
(W + (K + q) × J−1) / (K + q) × J
It can be expressed as Here, W is the total number of bits of binarized confidential information, K is the number of unit bits for color information conversion determined by the number of color bits used for embedding the binarized confidential information data, and q is a ten evolution The number of unit bits of the distance information, J is the number of confidential information blocks included in the large confidential information block. Actually, the confidential information area is a very small area, and the number of confidential information areas is usually about several thousand.
[0072]
As can be seen from the above description, the number of bits of the confidential information area prepared for embedding the dot data of one confidential information large block needs to be larger than the number of bits of the dot data of the confidential information large block. .
[0073]
The reference point code is a reference point mark for indicating a reference point on the printed paper and limits the embedding direction and order (vertical and horizontal) of dot data in the confidential information block, and may be a fixed value. And may be uniquely given by an encryption key. It is preferable to print at least one mark having asymmetry for distinguishing the upper, lower, left and right sides of the sheet on the sheet, but at least one of the reference point marks is an asymmetry necessary for this type of discrimination. It is good also as the mark which gave the property.
[0074]
In step 129, in order to embed the data contents of the confidential information block in the corresponding confidential information large block as color dot data by replacement in each confidential information area of the last reference information data DSC1 obtained in step 128, respectively. The process is executed. The process for embedding the confidential information data is performed by one of the decimal data of each set in the large block of confidential information corresponding to each reference point code from the position of the reference point code embedded in the reference information data. This is a processing step of creating composite information data by embedding a predetermined position determination code determined according to the other content at a position separated by a distance determined according to the content by replacement. Step 129 is repeatedly performed L (= N) times. In each execution, the content of one confidential information large block is embedded. In this case, the reference point code and the position determination code may be fixed values or may be uniquely determined by an encryption key.
[0075]
This will be specifically described with reference to FIG. The first set of decimal data of the first confidential information block BC11 and the decimal data of the second confidential information block BC12 included in the first confidential information large block obtained in step 125 are the first. It is taken in as two consecutive decimal data corresponding to the first reference point code (reference point mark RC1). The contents of these decimal number data are 174 and 2, and according to these values, the first decimal number data from the position of the reference point code indicating the first reference point mark RC1 already embedded in step 128 is obtained. In accordance with the contents of, a position determination code indicating a color position determination mark D2 unique to the value 2 which is the content of the decimal data of the second confidential information block BC12 is embedded by replacement at a position 174 bits apart.
[0076]
Similarly, the decimal data (156) and (8) of the third and fourth confidential information blocks BC13 and BC14 in the second set of the second set (156) is changed from the second reference point mark. The distance is shown, and (8) shows the position determination mark to be printed there. Note that it is possible to arbitrarily determine which of the decimal data of the two confidential information blocks made as one set is the distance information and which is the mark form information.
[0077]
Although not shown in the drawing, the decimal data of the confidential information block BC15 is the third decimal data of the fifth and sixth confidential information blocks BC15 and BC16 in the third set in the same manner. The distance from the reference point mark is indicated, and the decimal data of the confidential information block BC16 indicates the position determination mark to be printed there. Similarly, it is possible to arbitrarily determine which of the decimal data of the two confidential information blocks made as one set is the distance information and which is the mark form information. The composite information data is created as described above.
[0078]
FIG. 10B schematically shows this as in the case of FIG. 4A, and is 174 bits from the first reference point mark RC1 by the first reference point code. A unique position determination mark D2 representing the number 2 is printed as a position determination mark for the first set at a position away from the positive (+) direction. FIG. 11 shows an example of the position determination mark when the content of the decimal color data of the confidential information block is 1, 2, and 3. However, the position determination mark is not limited to these, and can be arbitrarily set. Of course, it may be determined.
[0079]
FIG. 12 shows an enlarged view of the dot pattern when the reference point mark and the position determination mark are actually embedded by replacement. FIG. 12 shows an example in which the distance information of the confidential information block is zero and the mark form information is 2. Here, the difference in the horizontal dots (pixels) between the reference point mark and the position determination mark D2 is zero.
[0080]
In step 130, print data that is dot-patterned according to the composite information data finally obtained in step 129 is created, and printing of public information in which confidential information is embedded is executed in accordance with this print data. As described above, this printing can be performed using a printing machine that digitally prints pixel data having a resolution of about 400 dpi or higher, for example, a laser printer.
[0081]
10 to 12, for the sake of explanation, the reference point mark and the position identification mark are represented as dot patterns having a size that can be identified with the eyes. However, since these marks are actually very small color marks whose size cannot be visually recognized, third parties do not notice their presence. Since the embedding area of the reference point code and the position determination code is very small, the public information image in which these codes are embedded is the same as the original public information image, and confidential information is embedded in this public information image. It is not possible to determine just by visual inspection.
[0082]
In the confidential information recording method described with reference to FIGS. 9 to 12, it is necessary to embed a plurality of reference point codes in the recording area set corresponding to the confidential information large block. It is also possible to embed only one reference point code in the recording area set corresponding to. It is also possible to embed one reference point mark for a plurality of m confidential information blocks.
[0083]
With reference to FIG. 13, an example of a confidential information recording method when only one reference point code is embedded in the recording area set corresponding to the large confidential information block will be described. First, the example shown in FIG. 13A will be described. In this case, the process for embedding the confidential information data is first embedded in the recording area set corresponding to the large confidential information block 1. A predetermined position determination mark D2 according to the content of the confidential information block BC12 is embedded by replacement at a position away from the position of the two reference point marks RC1 according to the content of the decimal data 174 of the confidential information block BC11. For the next confidential information block BC13, BC14, the position of the confidential information block B14 is separated from the position of the position determination mark D2 by the set of the confidential information blocks BC11, BC12 according to the content 156 of the decimal data of the confidential information block BC13. Processing to embed the position determination mark D8 is performed according to the contents. That is, starting from the reference point mark RC1, a predetermined distance corresponding to the confidential information blocks BC12, BC14,... Is cumulatively separated by a distance corresponding to the value of each confidential information block BC11, BC13,. Position determination marks D2, D8,... Are embedded.
[0084]
In the example shown in FIG. 13A, the position determination mark is embedded along a predetermined direction at intervals corresponding to the number of bits according to the content of the confidential information block, starting from the reference point mark RC1. However, as shown in FIG. 13B, a position determination mark D2 corresponding to the confidential information block BC12 is embedded at a position 174 bits away from the reference point mark RC1 in the horizontal direction, and then from the reference point mark RC1. By repeatedly embedding the position determination mark D8 corresponding to the confidential information block BC14 at a distance of 156 bits according to the contents of the confidential information block BC13 from a position that is a predetermined fixed distance KN in the vertical negative direction, the predetermined position determination code is successively The method of embedding may be used.
[0085]
Next, an example of an embodiment of the invention of claim 4 will be described with reference to FIGS. The creation of the confidential information recording document to which the invention of claim 4 is applied is the same as that of the embodiment of the invention of claim 1 except for the processing contents of steps 17 and 18 shown in FIG. Shows only steps 47 and 48 corresponding to steps 17 and 18, and other steps are not shown, and will be described with reference to FIG. 1 as necessary.
[0086]
In step 47, N (= [(n + 2) / 3]) reference point codes are represented by dots for the number n of confidential information blocks B1, B2,..., Bn obtained in step 15 by repeated execution. It is sequentially embedded in the public information data by replacement. If n is not a multiple of 3, “0” corresponding to the number of blocks corresponding to the remainder is added to the end of the binarized confidential information data. The content of one block is (00000000).
[0087]
The creation of reference information data in step 47 is performed as follows. First, in the first execution of step 47, a process of embedding the reference point code corresponding to the confidential information block B1 by replacing it with the dotized public information data is executed, whereby reference information data is obtained. When the above-described series of data processing in step 47 is completed, step 47 is executed again, and the reference point code corresponding to the confidential information block B2 is embedded in the previously obtained reference information data. In this way, the reference information data obtained in step 47 is used as updated dotized public information data in the subsequent processing in step 47. The above-described processing in step 47 is repeatedly executed L (= N) times according to the number of confidential information blocks obtained previously.
[0088]
The reference point code is a reference point mark for indicating a reference point on the printed paper, and the dot data embedding direction and order (vertical, horizontal) are determined on the printed paper. The reference point mark for indicating the reference point is provided. It is preferable to print at least one mark having asymmetry for distinguishing the upper, lower, left and right sides of the sheet on the sheet, but at least one of the reference point marks is an asymmetry necessary for this type of discrimination. It is good also as the mark which gave the property.
[0089]
In step 48, processing for embedding the contents of the confidential information blocks B1, B2, B3,..., Bn in the reference information data obtained in step 47 is executed.
[0090]
The process for embedding the confidential information data is performed on the three decimal data of the confidential information blocks B1, B2, and B3 corresponding to the respective reference point codes from the position of the reference point code embedded in the reference information data. This is a processing step for creating composite information data by embedding predetermined position determination codes determined according to the remaining decimal data at positions separated according to the contents of two of them. The reference point code and the position determination code may be fixed values or may be uniquely determined by an encryption key.
[0091]
In the case of the embodiment shown in FIG. 14, three consecutive confidential information blocks (B1, B2, B3), (B4, B5, B6),. The composite information data is created by embedding a position determination code according to the content of the remaining decimal data at a position separated according to the two decimal data of the decimal data of the set of confidential information blocks. As described above, when n is not a multiple of 3, the value of each block corresponding to the remainder of the confidential information block is processed as (0).
[0092]
Here, the reference point code is defined as (101010), and the pixel data for printing is printed by a printer having a resolution of about 400 dpi or higher as will be described later. Therefore, the reference point pattern (reference point mark) printed on the paper surface by the reference point code is extremely small and it is impossible to visually determine its presence, and a reference point mark printed on the paper by a third party. You will not notice the existence of. The same applies to a position determination mark described later.
[0093]
This will be specifically described with reference to FIG. When step 48 is entered, as shown in FIG. 15A, first, the decimal data (174) of the first confidential information block B1 and the second number are assigned to the first reference point mark R1. Is referred to the decimal data (56) of the confidential information block B2 of the first reference point mark R1, and is 174 bits in the horizontal (+) direction from the reference point code indicating the first reference point mark R1, in the negative direction in the vertical direction A position determination code indicating a position determination mark D128 unique to the decimal data (128) of the third confidential information block B3 is embedded at the 56-bit position by replacement. In FIG. 15A, unlike FIG. 2A, the state when printed is schematically shown. However, the method for embedding data itself is essentially the same as that shown in FIG. There is no change.
[0094]
In this way, the decimal data of the following three confidential information blocks B4, B5, and B6 are associated with the second and subsequent reference point marks in the same manner, and a set of these three decimal data. The required position determination code is embedded in the reference information data by replacing the data so that the unique position determination mark is printed at the required position. Therefore, the distance of each position determination mark from the corresponding reference point mark and the contents of the mark indicate the contents of the three confidential information blocks. In addition, it is arbitrary which two decimal numbers of the decimal numbers of one set of three confidential information blocks are used as distance information. Synthesis information data is created as described above.
[0095]
In other words, the step 48 is L (= N) until the contents of the three confidential information blocks in the Nth set are embedded in the reference information data in relation to the reference point code at the Nth position. It is executed repeatedly.
[0096]
In this way, in step 48, the confidential information blocks prepared in step 15 are grouped in groups for a plurality of reference point codes embedded in the reference information data, and their contents are determined by the method described above. The combined information data is obtained by repeatedly executing the embedding process L times. As can be understood from the above description, the composite information data obtained in the process of step 48 is treated as updated reference information data in the confidential information block embedding process of step 48 which is repeated again immediately after that. It will be.
[0097]
FIG. 15B shows an example of the position determination mark when the content of the decimal data is 128, 129, and 130. However, the position determination mark is not limited to these and is arbitrarily determined. Of course, it is also good. FIG. 15C shows an enlarged view of the dot pattern when the reference point mark and the position determination mark are actually embedded by replacement. FIG. 15C shows an example in which the values of one set of confidential information blocks are both zero. The dot (pixel) difference between the reference point mark and the position determination mark is vertical or horizontal. Zero.
[0098]
Next, an example of an embodiment of the invention of claim 4 in which the position determination mark is embedded as a color dot pattern will be described with reference to FIGS.
[0099]
In the example of the embodiment according to the processing procedure shown in FIG. 16, the content of confidential information is recorded in a color public information image using an 8-color dot pattern. When embedding a color dot of the same color at a position overlapping with the color dot of the public information image, the color dot is left as it is. Conversely, when embedding a color dot of a different color, the color dot of the different color is replaced. As a result, a large amount of confidential information can be embedded even when there are few white areas in the color public information image. The method of embedding confidential information data in a color public information image can be freely set by an encryption key. However, in order to prevent humans from visually detecting the position where the color dot pattern according to the confidential information is embedded, it is desirable that the resolution is 400 dpi or higher and the embedded density of confidential information is 1% or lower.
[0100]
Hereinafter, the method will be described with reference to the flowchart of FIG. 16. In step 221, first, necessary confidential information is binarized to obtain binarized confidential information data. This confidential information may be image data, computer program data, audio data, or musical tone data in addition to character data. In the next step 222, the binarized confidential information data obtained in step 221 is blocked to a size of (K + 2q) × J bits to create a large confidential information block. Here, K indicates the number of unit bits for color information conversion determined by the number of color dots used for embedding the binarized confidential information data. For example, when 8 color dots are used, color information conversion is performed in units of 3 bits, so K = 3. When 16 colors are used, color information conversion is performed in units of 4 bits, so K = 4, and 32 colors are converted. When the color information is converted in units of 5 bits, K = 5, and in the case of 64 colors, color information is converted in units of 6 bits, so K = 6. Similarly, q is the number of unit bits indicating the distance from the reference point.
[0101]
As can be seen from the above description, in the present embodiment, one confidential information block is composed of (K + 2q) bits, and is also dot data indicating the contents of the confidential information block. K is the number of unit bits for color information conversion, and q is the number of unit bits for distance information conversion. Specifically, the content of one confidential information block is converted into a decimal number indicating one color dot such as a red dot, a black dot, a white dot,... And two decimal numbers indicating a distance. In order to be able to scramble a plurality of confidential information blocks as a unit, the confidential information large block is divided into (K + 2q) × J bits so that the plurality of confidential information blocks are included. It is. That is, J indicates the number of confidential information blocks in the confidential information large block. When J = 1, the confidential information large block consists of only one confidential information block. When the number of bits of the last large confidential information block obtained by dividing the binarized confidential information data into blocks of (K + 2q) × J bits is (K + 2q) × J bits or less, A bit of “0” is added to the end of the last confidential information large block so that it becomes (K + 2q) × J bits, and the number of bits of the last confidential information large block is also (K + 2q) × J bits. As a result, a plurality of large confidential information blocks each having (K + 2q) × J bits are created.
[0102]
In step 123, an encryption key is determined. This encryption key includes an encryption code indicating a rule for rearranging the large block of confidential information obtained by dividing the binarized confidential information data obtained in step 122 into (K + 2q) × J bits, A rearrangement method is designated in accordance with this, and a plurality of confidential information large blocks obtained in step 222 are rearranged in step 224. For the encryption here, for example, a conventional encryption system or a public key encryption system can be used. Although it depends on the amount of confidential information, it is usually several thousand blocks, and the confidential information block includes several thousand confidential information blocks.
[0103]
In step 225, the binary data of (K + 2q) × J bits in the confidential information large block is divided into K-bit units, and the binary data in K-bit units is deciphered according to the encryption key obtained in step 223. Convert to information. In addition, a set of binary data is converted into decimal numbers in two divided into q bit units. In this embodiment, since eight color dots are used, K = 3, and 3-bit binary data is converted into any numerical value from 1 to 8. In this way, the binary data in the first confidential information large block is converted into chromaticity and information, and the confidential information blocks BC13 and BC16 containing the color dot information are divided into two in q bit units. A set of binary data, BC11, BC12, BC14, BC15,... Is obtained in step 225. The same applies to the second, third,... Confidential information large blocks. The color dot color can be expressed arbitrarily as 1 is white, 2 is red, 3 is blue,..., 8 is black. Also, the color setting method using the encryption key is “000” representing 8 as black, “001” representing 3 as blue, “010” representing 2 as red, and “111” representing 1 as white. Such a method can be appropriately employed.
[0104]
Next, in step 226, the color public information image such as a sentence, a picture, or the like that is to be printed on the paper surface F is converted into a color dot to generate color dot public information data DNC1. In step 227, confidential information areas corresponding to the number of large blocks of confidential information obtained in step 222 are set. In the case of this embodiment, since the confidential information is composed of three confidential information large blocks, three confidential information areas XC, YC and ZC are set.
[0105]
In step 228, the same number of reference point codes as the confidential information block J in the confidential information large block are embedded in one confidential information area so as not to overlap according to the encryption key. First, a color reference point code DRC1 indicating a reference point mark is prepared, and the first reference point code DRC1 is confidential information with respect to the dot public information data DNC1 which is a color dot containing the public information image GC. The reference information data DSC1 is generated by combining the color reference point mark RC1 to indicate the reference position of the region XC. Therefore, the content of the reference information data DSC1 is obtained by adding the reference point mark RC1 (by the reference point code DRC1 embedded by replacement) to the public information image GC.
[0106]
Next, the process of embedding the second reference point code DRC2 in the confidential information area XC is executed again. The dotted public information data DNC1 in which the reference point code DRC2 is embedded in this case is the reference information data DSC1 updated by the immediately preceding process. In this way, the reference information data DSC1 obtained in step 228 is used as updated dotized public information data DNC1 in the subsequent repetitive processing in step 228, and the above-described processing in step 228 is obtained first. The process is repeatedly executed as many times as the number of confidential information areas (three in this embodiment).
[0107]
As a result, final reference information data DSC1 in which the reference point marks RC1, RC2, RC3, RC4, RC5, RC6 are respectively embedded in the three confidential information areas XC, YC, ZC is created, and the next step 229 is performed. enter. Note that the number of repetitions of step 228 is L
[(W + KJ + 2qJ-1) / (KJ + 2qJ)]
It can be expressed as Here, W is the total number of bits of the binarized confidential information, K is the number of unit bits for color information conversion determined by the number of color bits used for embedding the binarized confidential information data, and q is a ten evolution. The number of unit bits of distance information, J is the number of confidential information blocks included in the confidential information large block. Actually, the confidential information area is a very small area, and the number of confidential information areas is usually about several thousand. As can be seen from the above description, the number of bits of the confidential information area prepared for embedding the dot data of one confidential information large block needs to be larger than the number of bits of the dot data of the confidential information large block. .
[0108]
The reference point code is a reference point mark for indicating a reference point on the printed paper and limits the embedding direction and order (vertical and horizontal) of dot data in the confidential information block, and may be a fixed value. And may be uniquely given by an encryption key. It is preferable to print at least one mark having asymmetry for distinguishing the upper, lower, left and right sides of the sheet on the sheet, but at least one of the reference point marks is an asymmetry necessary for this type of discrimination. It is good also as the mark which gave the property.
[0109]
In step 229, in order to embed the data content of the confidential information block in the corresponding confidential information large block as color dot data by replacement in each confidential information area of the last reference information data DSC1 obtained in step 228, respectively. The process is executed. The process for embedding the confidential information data is performed using the decimal data of each set in the large block of confidential information corresponding to each reference point code from the position of the reference point code embedded in the reference information data. This is a processing step of creating composite information data by embedding predetermined position determination codes determined according to the contents of the remaining decimal data at positions separated by a distance determined according to the two contents, respectively, by substitution. Step 229 is repeated L times. In each execution, the content of one confidential information large block is embedded. In this case, the reference point code and the position determination code may be fixed values or may be uniquely determined by an encryption key.
[0110]
Next, this will be specifically described with reference to FIG. When step 229 is entered, as shown in FIG. 17B, first, the decimal data (74) and the second number of the first confidential information block BC11 with respect to the first reference point mark RC1. With reference to the decimal data (56) of the confidential information block BC12, 74 bits in the horizontal (+) direction from the reference point code indicating the first reference point mark RC1, and in the negative direction in the vertical direction A position determination code indicating a unique position determination mark D2 is embedded in the decimal data (2) of the third confidential information block BC13 at the 56-bit position by replacement. In FIG. 17B, unlike FIG. 2A, the state when printed is schematically shown. However, the method for embedding data itself is essentially the same as that shown in FIG. There is no change.
[0111]
Similarly, the decimal data of the following three confidential information blocks BC14, BC15, and BC16 are associated with the second and subsequent reference point marks in the same manner, and according to these three sets of decimal data. The required position determination code is embedded in the reference information data by data replacement so that the unique position determination mark is printed at the required position. In this case, the decimal data (104) of the fourth confidential information block BC14 and the decimal data (96) of the fifth confidential information block BC15 are referred to for the second reference point mark RC2. The decimal number of the sixth confidential information block BC16 at a position of 104 bits in the horizontal (+) direction and 96 bits in the vertical negative direction from the reference point code indicating the second reference point mark RC2. A position determination code indicating a unique position determination mark D5 is embedded in the data (5) by replacement. Therefore, the distance of each position determination mark from the corresponding reference point mark and the contents of the mark indicate the contents of the three confidential information blocks. In addition, it is arbitrary which two decimal numbers of the decimal numbers of one set of three confidential information blocks are used as distance information. Synthesis information data is created as described above.
[0112]
FIG. 18 shows examples of the position determination marks D1, D2, and D3 when the value of the decimal color data of the confidential information block is 1, 2, and 3. However, the position determination marks are not limited to these. Of course, it may be determined arbitrarily. FIG. 19 shows an enlarged view of the dot pattern when the reference point mark and the position determination mark are actually embedded by replacement. FIG. 19 shows an example in which the values of one set of confidential information blocks are both zero. The dot (pixel) difference between the reference point mark and the position determination mark is zero in both the vertical and horizontal directions.
[0113]
In step 230, print data that is dot-patterned according to the composite information data finally obtained in step 229 is created, and printing of public information in which confidential information is embedded is executed in accordance with this print data. As described above, this printing can be performed using a printing machine that digitally prints pixel data having a resolution of about 400 dpi or higher, for example, a laser printer.
[0114]
In FIG. 17 to FIG. 19, the reference point mark and the position identification mark are represented as dot patterns having a size that can be identified with the eyes for the sake of explanation. However, since these marks are actually very small color marks whose size cannot be visually recognized, third parties do not notice their presence. Since the embedding area of the reference point code and the position determination code is very small, the public information image in which these codes are embedded is the same as the original public information image, and confidential information is embedded in this public information image. It is not possible to determine just by visual inspection.
[0115]
Next, an example of an embodiment of the invention of claim 5 will be described with reference to FIGS. The creation of the confidential information recording document to which the invention of claim 5 is applied is the same as that of the embodiment of the invention of claim 1 except for the processing contents of steps 17 and 18 shown in FIG. Only steps 57 and 58 corresponding to steps 17 and 18 are shown, and other steps are not shown, and will be described with reference to FIG. 1 as necessary.
[0116]
In step 57, N (= [(n + 3) / 4]) reference point codes are added to the dotted public information data with respect to the number n of confidential information blocks B1, B2,..., Bn obtained in step 15. It is sequentially embedded by replacement. If n is not a multiple of 4, “0” corresponding to the number of blocks corresponding to the remainder is added to the end of the binarized confidential information data. The content of one block is (00000000). A reference point code that is 1/4 (N) of the number of confidential information blocks obtained in step 15 is embedded in the dotized public information data, whereby reference information data is obtained.
[0117]
The creation of reference information data in step 57 is performed as follows. First, in the first execution of step 57, a process of embedding the first reference point code in the dotized public information data is executed, whereby reference information data is obtained. When the above-described series of data processing in step 57 is completed, step 57 is executed again, and the second reference point code is embedded into the previously obtained reference information data. In this way, the reference information data obtained in step 57 is used as updated dotized public information data in the subsequent processing in step 57. The above-described processing in step 57 is repeatedly executed L (= N) times according to the number of confidential information blocks obtained previously.
[0118]
The reference point code is for determining the embedding direction and order (vertical and horizontal) of the confidential information block to be embedded and giving a reference point mark for indicating the reference point on the printed paper. It is preferable to print at least one mark having asymmetry for distinguishing the upper, lower, left and right sides of the sheet on the sheet, but at least one of the reference point marks is an asymmetry necessary for this type of discrimination. It is good also as the mark which gave the property.
[0119]
In step 58, processing for embedding the contents of the confidential information blocks B1, B2, B3,... Bn in the reference information data obtained in step 57 is executed.
[0120]
The processing for embedding the confidential information data is as described above, but two sets of decimal numbers in which one set corresponding to each reference point code is composed of two blocks from the position of the reference point code in the reference information data. This is a processing step for creating composite information data by embedding a position discrimination code unique to each set by substitution at positions separated according to the contents of the decimal data of each set according to the contents of the data. The reference point code and the position determination code may be fixed values or may be uniquely determined by an encryption key.
[0121]
In the case of the embodiment shown in FIG. 20, two sets of decimal data, each of which is a set of two consecutive confidential information blocks, form one group, and a reference point corresponding to each group determines the number of groups. According to the contents of the decimal number data, the composite information data is created by embedding a position determination code corresponding to a position determination mark unique to each group constituting the group by substitution at a position determined according to the one set of decimal number data. To do. When n is not a multiple of 4, the value of each block corresponding to the remainder of the binarized confidential information block is processed as (0). This is as described above. When some or all of the position determination marks overlap, the logical sum of the corresponding bits of two predetermined position determination codes is taken and embedded as a position determination code for obtaining the result.
[0122]
Here, the reference point code is defined as (101010), and the pixel data for printing is printed by a printer having a resolution of about 400 dpi or higher as will be described later. Therefore, the reference point pattern (reference point mark) printed on the paper surface by the reference point code is extremely small and it is impossible to visually determine its presence, and a reference point mark printed on the paper by a third party. You will not notice the existence of. The same applies to a position determination mark described later.
[0123]
This will be specifically described with reference to FIG. As shown in FIG. 21A, the confidential information blocks B1 (174), B2 (56), B3 (128), and B4 (78) obtained in step 15 constitute one set of two blocks. In this example, B1 and B2 are the first set, and B3 and B4 are the second set. Further, the first group and the second group are set as the first group.
[0124]
One reference point mark is assigned to one group. Therefore, the first reference point mark R1 is assigned to the group including the confidential information blocks B1 to B4. Then, the first set of two decimal data 174 and 56 is referred to, and from the reference point code indicating the first reference point mark R1, 174 bits in the horizontal positive (+) direction and vertical negative ( A position determination code indicating a position determination mark D12 predetermined for the first set is embedded at a position of 56 bits in the-) direction. In FIG. 21A, unlike FIG. 2A, the state when printed is schematically shown. However, the technique relating to the embedding of the position determination code itself is shown in FIG. There is essentially no difference from that.
[0125]
The same processing is performed for the first reference position mark R1 for the confidential information blocks B3 and B4 constituting the second set, and the vertical direction is 128 bits in the positive (+) direction in the horizontal direction. A position determination code indicating a unique position determination mark D34 defined for the second set is embedded at a 78-bit position in the negative (−) direction.
[0126]
In this manner, step 58 is performed until two position determination codes representing the contents of the last group of confidential information blocks corresponding to the reference point code of the Nth position are embedded in the reference information data by replacement. Are repeatedly executed L (= N) times.
[0127]
In this way, in step 58, the above-described embedding by replacing the position determination code according to the number of confidential information blocks prepared in step 15 is performed on the plurality of reference point codes embedded in the reference information data. Run repeatedly. A position determination code is embedded at a position indicating each content of the confidential information block data in the reference information data to obtain composite information data. As can be understood from the above description, the combined information data obtained in the process of step 58 is treated as updated reference information data in the confidential information block embedding process of step 58 which is repeated again immediately after that. It will be.
[0128]
FIG. 21B shows examples of position determination marks for the first, second, third, and fourth blocks, but the position determination marks are not limited to these and may be arbitrarily determined. Of course. The two position determination marks may be patterns with different black and white dots or appropriate patterns with color dot information. FIG. 21C shows an example in which the values of the two confidential information blocks constituting one group are both zero. The difference in dots (pixels) between the reference point mark and the position determination mark is either vertical or horizontal. The direction is zero.
[0129]
Therefore, a plurality of position determination marks embedded with respect to one reference point mark each indicate the data contents of two confidential information blocks, and the number of those groups in the position determination mark form assigned thereto. You can see if it is a block. Therefore, a large amount of confidential information data is included in one position determination mark, which is suitable for embedding a large amount of data.
[0130]
As can be seen from the above description, in the embodiment of FIG. 20, some or all of the two position determination marks may overlap. In this way, the processing at the time of decoding when part or all of the position determination marks overlap will be described with reference to FIG. 22 when the dot pattern of the position determination code is monochrome. The case where the position determination code is color will be described with reference to FIG.
[0131]
The public information dot pattern PO shown in (A) of FIG. 22 is added to the position determination code dot patterns PX and PY shown in (B) and (C) of FIG. A case where the post-combination dot pattern PZ shown in FIG. 22D is obtained by embedding by replacement as shown in FIG. 22 will be described as an example.
[0132]
When the post-combination dot pattern PZ shown in FIG. 22D is given, the decoding side knows in advance the pattern contents of the position determination code dot patterns PX and PY embedded in the public information ( In this case, the determination is made as to which of the upper left pattern and the lower right pattern is PX or PY in the post-combination dot pattern PZ. For this reason, first, two types of 4 × 4 dot patterns at arbitrary positions are extracted from the post-combination dot pattern PZ, the combination is inspected over the entire region, and at least a portion of the two types having overlapping portions is included. Extract the dot pattern. In the example of FIG. 22, the first extraction dot pattern PA and the second extraction dot pattern PB shown in FIGS. 22E and 22F are extracted. The overlap dot pattern of these extracted dot patterns PA and PB is a 2 × 2 dot overlap portion dot pattern Z shown in FIG. Here, the logical product of the lower left 2 × 2 dots of the position determination code dot pattern PX and the upper right 2 × 2 dots of the position determination code dot pattern PY coincides with the overlapping portion.
[0133]
However, since the position determination code dot pattern PX and the position determination code dot pattern PY are already known, the lower right 2 × 2 dot portion of the first extraction dot pattern PA is regarded as the corresponding portion of the position determination code dot pattern PX. The dot pattern of FIG. 22 (H) obtained by replacement corresponds to the position determination code dot pattern PX, and the upper left 2 × 2 dot portion of the second extracted dot pattern PB corresponds to the position determination code dot pattern PY. It can be confirmed that the dot pattern of (I) in FIG. 22 obtained by replacing the portion matches the position determination code dot pattern PY.
[0134]
As a result, since the position of the position determination code dot pattern PX and the position of the position determination code dot pattern PY in the post-combination dot pattern PZ can be confirmed, the position determination code dot pattern PX and the position determination code dot pattern PY are Even if they overlap, if they overlap and embed the logical product of the two parts, it will not become undecipherable.
[0135]
The color public information dot pattern PCO shown in FIG. 23A is replaced with the color position determination code dot patterns PCX and PCY shown in FIGS. 23B and 23C. A case will be described as an example in which the replacement is performed in accordance with the color dot data replacement method shown in (J) of Fig. 23 and the combined dot pattern PCZ shown in Fig. 23 (D) is obtained. The number of color dots used is eight.
[0136]
When the combined dot pattern PCZ shown in FIG. 23D is given, the content of the position determination code dot patterns PCX and PCY embedded in the public information is known in advance on the decoding side ( Since it is determined by the encryption key as a matter of course, in this case, in this case, it is a discriminating operation to determine whether the upper left pattern or the lower right pattern is PCX or PCY in the dot pattern PCZ after synthesis. Become. For this reason, two types of 3 × 3 dot patterns at arbitrary positions are extracted from the post-combination dot pattern PCZ, the combination is inspected over the entire area, and at least part of the two types of dot patterns having overlapping portions To extract.
[0137]
In the example of FIG. 23, the first extraction dot pattern PCA and the second extraction dot pattern PCB shown in (E) and (F) of FIG. 23 are extracted. The overlapping dot pattern of these extracted dot patterns PCA and PCB is a 1 × 1 dot overlapping dot pattern CZ shown in FIG. Here, according to the value of the lower right 1 × 1 dot of the position determination code dot pattern PCX and the upper left 1 × 1 dot of the position determination code dot pattern PCY, according to the color dot data replacement method shown in FIG. The replaced value matches the overlapping dot pattern CZ.
[0138]
This will be described with reference to FIG. A value identical to the value (1) of the lower right 1 × 1 dot of the position determination code dot pattern PCX is searched from (J) of FIG. 23, and the upper left 1 × 1 of the position determination code dot pattern PCY in the clockwise direction from that position. The value at the position (J) in FIG. 23 advanced by the same value as the dot value (3) is set as the value (4) of the overlapping dot pattern CZ.
[0139]
Since the position determination code dot pattern PCX and the position determination code dot pattern PCY are already known, the lower right 1 × 1 dot value of the first extraction dot pattern PCA and the upper left 1 × 1 dot of the second extraction dot pattern PCB The dot pattern of (H) of FIG. 23 obtained by replacement according to the color dot data replacement method shown in (J) of FIG. 23 is the position determination code dot pattern PCX and FIG. 23 (I) of FIG. It can be confirmed that the dot pattern matches the position determination code dot pattern PCY.
[0140]
As a result, since the position of the position determination code dot pattern PCX and the position of the position determination code dot pattern PCY in the combined dot pattern PCZ can be confirmed, the position determination code dot pattern PCX and the position determination code dot pattern PCY Even if they overlap, if the overlapping portion is replaced and embedded in accordance with the color dot data replacement method shown in FIG.
[0141]
The effects of the various confidential information recording methods described above are summarized below.
(1) A third party cannot understand the existence of confidential information recorded on paper.
(2) Even if a playback device is obtained by a third party, it is unlikely that confidential information will be decrypted.
(3) Since a large amount of confidential information can be embedded, digital information such as character information, audio information, image information, and computer programs can be combined and recorded or reproduced on paper.
(4) No special recording / playback device is required.
(5) Since it is printed on paper and can be easily copied, confidential information can be added, modified and deleted by cutting and pasting.
(6) A large number of copies can be made in a short time using a copying machine.
(7) Information recorded using a facsimile can be sent to a remote location in a short time.
[0142]
FIG. 24 is a block diagram showing an example of the configuration of a confidential information recording / reproducing system for recording / reproducing confidential information by the method of the present invention described with reference to FIGS. In the recording system denoted by reference numeral 100, 101 is a personal computer, in which confidential information composed of digital information such as voice information, image information, and computer programs is stored as binarized information in addition to character information. In addition, public information is also stored as binarized information.
[0143]
The personal computer 101 uses public information and confidential information using a predetermined encryption key by any of the methods described in FIGS. 1, 3, 5, 7, 9, 14, 14, 16, and 20. Are combined and converted into print data such as a dot code. The printer 102 prints public information in which confidential information is embedded in accordance with the print data on a sheet with a resolution of 400 dpi or higher. The print information obtained in this way can be copied in large quantities by the copying machine 103, and can be sent by mail or to a desired partner by the facsimile apparatus 104.
[0144]
In the reproduction system indicated by reference numeral 200, the imaged information received by the facsimile apparatus 201 is input to the personal computer 202. Note that the document sent by mail is read by the dot pattern of the information printed on the paper by the scanner 203, and the read dot pattern data is input to the personal computer 202.
[0145]
In the personal computer 202, the confidential information embedded in the public information is separated and extracted by using the restoration key corresponding to the encryption key used for the confidential information embedding process performed on the recording system 100 side. Play. The confidential information reproduced by the personal computer 202 is printed by the printer 204 to be a document. The reproduced confidential information may be displayed on a CRT display device (not shown), or may be output by voice using a speaker or the like (not shown).
[0146]
FIG. 23 shows an encrypted information recording / reproducing system as an example of a system to which the method of the present invention is applied. This exemplified system has a configuration in which confidential information that cannot be leaked to a third party is embedded as information such as a dot pattern in public information imaged using an encryption key and decrypted using a restoration key. The embedded information may be printed on paper or transferred to another computer on a computer network as image information.
[0147]
Application examples of this system include electronic commerce, digital cash, prepaid card, approval document, contract document, resume, assessment table, and the like.
[0148]
The components of this system are a personal computer having a word processor function, encrypted information recording software, a printer, a scanner, encrypted information reproduction software, LAN, and WAN.
[0149]
Other forms of the system to which the method of the present invention is applied will be described separately below.
[0150]
(A) Digital signature
The character information is printed on a sheet of paper as a human-readable character that can be deciphered at the same time, and the information is embedded as information such as a dot pattern on the sheet of paper using an encryption key (private key). The approver resolves the embedded information using the restoration key (public key), compares it with the character information, and confirms that they are the same. Unless a third party obtains an encryption key (private key), the embedded information cannot be altered.
[0151]
Application examples of this system include electronic commerce, digital cash, approval documents, contract documents, identification cards, and the like.
[0152]
The components of this system are a personal computer having a word processor function, encrypted information recording software, a printer, a scanner, and encrypted information reproduction software.
[0153]
(B) FAX information compression and transfer device
A plurality of pieces of character information are compressed and printed as dot codes on one sheet of paper, and transmitted by FAX. It is possible to send a character amount (several thousand to 10,000 characters) that is several times to ten times as large as one A4 sheet. It can be applied to FAX transmission of business documents.
[0154]
The components of this system are a personal computer having a word processor function, encrypted information recording software, a printer, a G3-compatible FAX with a resolution of 200 dpi, and encrypted information reproduction software.
[0155]
(C) Multimedia information recording / playback device
Multimedia information such as audio information, color image information, and computer programs is embedded as information such as dot patterns in character information and graphic information. The embedded information is taken out and reproduced on a print or CRT display device.
[0156]
Application examples of this system include documents with embedded human voices (business instructions, correspondence correspondence corrections, blind letters), documents with embedded color images (advertisements, manuals), documents with embedded program data (design) Drawings, NC machine programs).
[0157]
The components of this system are a microphone, a speaker, a still camera, a video device, a scanner, a personal computer having a word processor function, encrypted information recording software, a printer, encrypted information reproduction software, and the like.
[0158]
(D) Information storage medium system
Multimedia information such as character information, audio information, color image information, and a computer program is recorded on paper as information such as a dot pattern. The information storage medium has features such as ultra-low cost, easy handling, easy duplication, transmission by FAX, and easy transportation.
[0159]
Application examples of this system include storage and distribution of business documents, computer programs, commemorative photos, music, and the like.
[0160]
The components of this system are a microphone, a speaker, a still camera, a video device, a scanner, a personal computer having a word processor function, encrypted information recording software, a printer, encrypted information reproduction software, and the like.
[0161]
【The invention's effect】
The effects of the present invention are as follows.
(1) A third party cannot understand the existence of confidential information recorded on paper.
(2) Even if a playback device is obtained by a third party, it is unlikely that confidential information will be decrypted.
(3) Since a large amount of confidential information can be embedded, digital information such as character information, audio information, image information, and computer programs can be combined and recorded or reproduced on paper.
(4) No special recording / playback device is required.
(5) Since it is printed on paper and can be easily copied, confidential information can be added, modified and deleted by cutting and pasting.
(6) A large number of copies can be made in a short time using a copying machine.
(7) Information recorded using a facsimile can be sent to a remote location in a short time.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a method for creating a confidential information recording document for explaining an example of an embodiment of the invention according to claim 1;
FIG. 2 is an explanatory diagram for explaining confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 1;
FIG. 3 is a partial flowchart showing a main part of a method for creating a confidential information recording document for explaining an example of an embodiment of the invention according to claim 2;
FIG. 4 is an explanatory diagram for explaining confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 3;
FIG. 5 is a partial flowchart showing a main part of a method for creating a confidential information recording document for explaining a modification of the example of the embodiment of the invention described in claim 2 shown in FIG. 3;
6 is an explanatory diagram for explaining confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 5;
FIG. 7 is a partial flowchart showing a main part of a method for creating a confidential information recording document for explaining an example of an embodiment of the invention according to claim 3;
FIG. 8 is an explanatory diagram for explaining confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 7;
FIG. 9 is a flowchart showing a method for creating a confidential information recording document for explaining another example of the embodiment of the invention according to claim 3;
FIG. 10 is an explanatory diagram for explaining confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 9;
11 is a pattern diagram showing a pattern example of a position identification mark used for confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 9;
FIG. 12 is an explanatory diagram for explaining confidential information data embedding processing when distance information is zero in the confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 9;
FIG. 13 is an explanatory diagram of confidential information data embedding processing for explaining a modification of the embodiment of the invention according to claim 3 shown in FIG. 9;
FIG. 14 is a partial flowchart showing a main part of a method for creating a confidential information recording document for explaining an example of an embodiment of the invention as set forth in claim 4;
FIG. 15 is an explanatory diagram for explaining confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 14;
FIG. 16 is a flowchart showing a method for creating a confidential information recording document for explaining another example of the embodiment of the invention according to claim 4;
FIG. 17 is an explanatory diagram for explaining confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 16;
FIG. 18 is a pattern diagram showing a pattern example of a position identification mark used for confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 16;
FIG. 19 is an explanatory diagram for explaining confidential information data embedding processing when distance information is zero in the confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 16;
FIG. 20 is a partial flowchart showing a main part of a method for creating a confidential information recording document for explaining an example of an embodiment of the invention according to claim 5;
FIG. 21 is an explanatory diagram for explaining confidential information data embedding processing in the confidential information recording document creation processing shown by the flowchart of FIG. 20;
FIG. 22 is an explanatory diagram for explaining processing on the decryption side in the case where duplicate position determination marks are created by the confidential information recording document creation processing shown in the flowchart of FIG. 20;
FIG. 23 is an explanatory diagram for explaining processing on the decryption side in the case where duplicate position determination marks are created by the color confidential information recording document creation processing shown in the flowchart of FIG. 20;
FIG. 24 is a block diagram showing an example of a system configuration for recording and reproducing confidential information by the method of the present invention.
[Explanation of symbols]
B1, B2, B3, B4, BC11, BC12, BC13, BC14, BC15, BC16, Bn Confidential information block
BC1 Large block of confidential information
D0, D1, D2, D3, D4, D5, D8, D12, D34, D56, D57, D58, D128, D129, D130 Position determination mark
DN1, DNC1 Dot disclosure information data
DR1, DRC1 reference point code
DS1, DSC1 reference information data
F paper
Public information image of GC color
PA, PCA First extraction dot pattern
PB, PCB Second extraction dot pattern
PO, PCO public information dot pattern
PX, PY, PCX, PCY Position determination code dot pattern
PZ, PCZ Composite dot pattern
R1, R2, R3, R4, RC1, RC2, RC3, RC4, RC5, RC6 reference point marks
XC, YC, ZC Confidential information area

Claims (6)

A confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a large number of reference point codes encoded with reference point marks in the dotted public information data to obtain reference information data;
A position in which two data blocks are selected from the plurality of data blocks and correspond to one of the plurality of reference point codes, and are separated from the corresponding reference point code by a distance indicated by the data of the two data blocks. Creating composite information data by sequentially repeating embedding a predetermined position determination code in the reference information data by replacement , and
Creating print data according to the composite information data;
Printing the image according to the composite information data on a print medium according to the print data. A confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a large number of reference point codes encoded with reference point marks in the dotted public information data to obtain reference information data;
A position in which one data block is selected from the plurality of data blocks and is made to correspond to one of the plurality of reference point codes, and is separated from the corresponding reference point code by a distance indicated by the data of the one data block. Creating composite information data by sequentially repeating embedding a predetermined position determination code in the reference information data by replacement , and
Creating print data according to the composite information data;
Printing the image according to the composite information data on a print medium according to the print data. A confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a large number of reference point codes encoded with reference point marks in the dotted public information data to obtain reference information data;
Two data blocks are selected from the plurality of data blocks and correspond to one of the plurality of reference point codes, and the data of one data block of the two data blocks is determined from the corresponding reference point code. A step of creating composite information data by successively repeating embedding a position determination code according to the content of the other data block of the two data blocks at a position indicated by a distance by replacement in the reference information data When,
Creating print data according to the composite information data;
Printing the image according to the composite information data on a print medium according to the print data. A confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a large number of reference point codes encoded with reference point marks in the dotted public information data to obtain reference information data;
Three data blocks are selected from the plurality of data blocks to correspond to any of the plurality of reference point codes, and any two data blocks of the three data blocks are selected from the corresponding reference point codes. Creating composite information data by sequentially repeating embedding a position determination code according to the contents of the remaining data block in the reference information data at positions separated by a distance indicated by the data ;
Creating print data according to the composite information data;
Printing the image according to the composite information data on a print medium according to the print data. A confidential information recording method for recording confidential information on a print medium on which a public information image is printed,
Converting required confidential information into binarized confidential information data;
Blocking the binarized confidential information data to obtain a number of data blocks;
Converting the public information image into dot public information data;
Embedding a large number of reference point codes encoded with reference point marks in the dotted public information data to obtain reference information data;
Two sets of two data blocks are selected from the plurality of data blocks to correspond to the plurality of reference point codes, and one of the two sets of data blocks is selected from the corresponding reference point codes. A position determination code unique to the one set is embedded in the reference information data at a position separated by a distance indicated by the data, and the other set of data of the two sets from the corresponding reference point code Creating composite information data by sequentially repeating embedding a position determination code unique to the other set in the reference information data at a position separated by a distance indicated by block data ; and
Creating print data according to the composite information data;
Printing the image according to the composite information data on a print medium according to the print data.   The number of data blocks obtained by blocking the binarized confidential information data is rearranged by an encryption key, and the synthesized information data is created by sequentially using the rearranged data blocks. 2. The confidential information recording method according to 2, 3, 4, or 5.

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