KR102108192B1 - Method, Apparatus and System for Inserting Watermark - Google Patents

Abstract

Disclosed are a watermark embedding method, apparatus and system, a watermark detecting method and apparatus, and a digital document protection system. The watermark embedding method detects a text area from a digital document, detects at least one text to be transformed among texts in the text area based on the user code, which is a unique binary code corresponding to a user device, and detects the user code. Based on this, it is possible to transform the detected at least one text. Therefore, upon display of a digital document, a text or the like included in the digital document can be modified using a simple and unique algorithm based on a user code associated with a user device.

Description

Method, Apparatus and System for Inserting Watermark}

The present invention relates to a watermark embedding method, an apparatus and system, a watermark detecting method and apparatus, and a digital document protection system, and more specifically, based on a user code associated with a corresponding user device when displaying a digital document. An efficient watermark insertion and detection technology capable of inserting a watermark into a digital document using an algorithm and detecting it.

Recently, with the development of digital information processing technology and the establishment of an infrastructure for digitization, it has entered a new information society. In this information-oriented society, almost all jobs and services related to life, such as office work, payment services, certificate issuance, banking, and e-commerce, are conducted through online and computerized environments. In recent years, most institutions, from developed countries to governments and private companies in developing countries, have introduced smart work to handle their work.

In this online and computerized environment, digital documents can be targeted for creation, viewing, storage, editing, and transmission. Here, the digital document may mean digitized information including text, images, or multimedia. Since digital documents are much easier to record, archive, transmit, and duplicate than paper documents of the past, paper documents are currently being replaced in almost all fields of society. The use of such digital documents is expected to increase in the future.

On the other hand, digital documents, on the other hand, are very vulnerable to leakage through illegal acts because of the nature of digitized information, it is very easy to copy or transmit without loss. For example, internal information of a digitally documented company can easily be leaked to the outside using a digital device by a person with unintended intent. In particular, due to the increasingly developed hacking techniques, enormous losses that determine the existence of governmental agencies and organizations due to the leakage of internal information from each private company are actually occurring.

Therefore, in order to create a healthy environment for using digital documents, a protection means capable of protecting digital documents from illegal acts is essential. A digital watermark is one of these protection measures, and technology for preventing illegal copying of digital documents and effectively protecting the copyright and ownership of information owners by embedding codes or patterns containing promised information into digital content or signals. to be.

These digital watermarks can be useful for finding the origin or reproduction path of the original without disturbing the user viewing the image or using the software. For example, Korean Patent Publication No. 2013-0039226 determines whether a watermark is displayed based on a message generated by an operating system and a screen watermark display policy when an application is executed or a digital document is opened by a user's manipulation, Disclosed is a display method and apparatus for displaying a watermark on a screen when it is determined to display the watermark.

Currently, many companies are researching algorithms and technologies that can embed digital watermarks. An efficient digital watermark system should be easy to detect and decipher so that it is possible to identify the leaked person when the document is leaked by shooting with a camera, etc., without being discriminated with the naked eye so as not to designate the reading of the document. In addition, it is not appropriate to use an overly complex watermark algorithm to place a burden on the system or to cause overflow of text or images due to document deformation.

Accordingly, there is an urgent need to develop an efficient new watermark system that guarantees strict security while reducing the burden on the system by simplifying the algorithm, and does not cause overflow of text or images included in digital documents.

Korea Patent Publication No. 2013-0039226

The present invention is to solve this problem, a method for inserting a watermark, a device and a system for transforming text or the like contained in a digital document using a unique algorithm based on a user code associated with a user device when displaying a digital document It is an object of the present invention to provide.

In addition, the present invention provides a watermark detection method and apparatus that facilitates discrimination of a digital document leaker when a digital document processed by the watermark insertion method and device is leaked through screen capture or photo shooting. There is another object of the invention.

Another object of the present invention is to provide a digital document protection system capable of protecting digital documents from illegal acts using the watermark embedding device and the watermark detection device.

To achieve this object, the present invention provides a watermark embedding method in one aspect. The watermark embedding method is performed by a watermark embedding device, the method comprising: detecting a text area from a digital document; Detecting at least one text to be modified among texts in the text area based on the user code which is a unique binary code corresponding to a user device; And modifying the detected at least one text based on the user code.

The watermark embedding method is based on at least one of a unique key of a security viewer provided on the user device, physical identification information of the user device, and user identification information corresponding to the user device. It may further include the step of generating.

The watermark embedding method includes: receiving a request for requesting the digital document from the user device; Requesting information necessary for generating the user code to the user device; And receiving information required to generate the user code from the user device.

The detecting of the at least one text may include detecting a text line to be transformed among text lines in the text area based on the user code. For example, detecting the text line to be modified may include: sequentially matching each text line in the text area to each bit value of the user code; And detecting a text line whose corresponding bit is a first value. The step of transforming the at least one text may include reducing the font size of the text in the detected text line or reducing the text thickness.

The detecting of the at least one text may include detecting the most consonants or vowels included in texts included in the text area; And detecting text to be transformed among texts including the detected consonants or vowels based on the user code. For example, detecting the text to be modified may include: sequentially matching each text including the detected consonant or vowel in the text area to each bit value of the user code; And detecting the text whose corresponding bit is the first value. The step of deforming the at least one text may include reducing the font size of the detected text to be deformed or reducing the text thickness.

The watermark embedding method includes: detecting an image area from the digital document; Dividing the detected image of the image area into predetermined detailed pieces; And based on the user code, applying a predetermined operation to the divided detailed pieces. For example, applying the predetermined operation may include: generating a bit stream based on the user code; And inserting the bit string using an exclusive OR (XOR) operation on the divided detail piece.

The watermark embedding method includes: converting a file extension of a digital document in which the at least one text is modified into a predetermined extension; And transmitting the digital document converted to the predetermined extension to the user device. The digital document transmitted to the user device is displayed by a predetermined security viewer provided on the user device, and access from a general viewer and other user devices may be blocked.

On the other hand, in order to achieve the object of the present invention described above, the present invention provides a watermark embedding apparatus in another aspect. The watermark embedding apparatus includes: an area detection unit that detects a text area from a digital document; And detecting at least one text to be transformed among texts in the text area based on the user code, which is a unique binary code corresponding to the user device, and detecting the text, based on the user code, which is a unique binary code. And a text processing unit that transforms at least one text.

The watermark insertion device, based on at least one of the unique key of the security viewer provided on the user device, the physical identification information of the user device and the user identification information corresponding to the user device, the user code The user code generation unit may be further included.

The watermark embedding device receives a request for requesting the digital document from the user device, requests information required to generate the user code from the user device, and receives information required to generate the user code from the user device It may further include a user code generator receiving from.

The text processing unit may detect a text line to be deformed among text lines in the text area based on the user code, and reduce the font size or text thickness of the text in the detected text line. For example, the text processing unit may sequentially associate each text line in the text area with each bit value of the user code, and detect a text line whose corresponding bit is the first value.

The text processing unit detects the most consonants or vowels included in texts included in the text area, and detects text to be transformed among texts containing the detected consonants or vowels based on the user code. Then, the font size of the detected text to be deformed may be reduced or the text thickness may be reduced. For example, the text processing unit may sequentially match each text including the detected consonant or vowel in the text area to each bit value of the user code, and perform text having a corresponding bit as a first value. .

The watermark embedding apparatus detects an image area from the digital document, divides the detected image of the image area into predetermined detail pieces, and performs an operation determined on the divided detail pieces based on the user code. The applied image processing unit may be further included. The image processing unit may generate a bit string based on the user code, and insert the bit string using an exclusive OR (XOR) operation on the divided detailed pieces.

The watermark embedding apparatus includes: a conversion unit that converts a file extension of the digital document in which the at least one text is modified into a predetermined extension; And a transmission unit transmitting the digital document converted to the predetermined extension to the user device. The digital document transmitted to the user device is displayed by a predetermined security viewer provided on the user device, and access from a general viewer and other user devices may be blocked.

On the other hand, in order to achieve the object of the present invention described above, the present invention provides a watermark embedding system in another aspect. The watermark embedding system includes: a user device requesting a digital document through a network; And detecting a text area from the digital document, detecting at least one text to be transformed among texts in the text area, based on a user code that is a unique binary code corresponding to the user device, and detecting the user code. Based on this, it may include a watermark embedding device for modifying the detected at least one text.

On the other hand, in order to achieve the other object of the present invention described above, the present invention provides a watermark detection method in another aspect. The watermark detection method includes: detecting a text area from a digital document image; Detecting a deformed text among texts in the text area by comparing the text in the text area with text in a corresponding area of the original image; And detecting the user code, which is a unique binary code that can identify the user device, based on the modified text.

The detecting of the user code may include detecting the user code based on matching a first value to a deformed text line among text lines in the text area. The detecting of the user code may include detecting the user code based on matching a first value to text containing the most consonants or vowels in the text area. The deformed text may be at least one of text with a reduced font size and text with a reduced text thickness.

On the other hand, in order to achieve another object of the present invention described above, the present invention provides a watermark detection device in another aspect. The watermark detection apparatus includes: an area detection unit that detects a text area from a digital document image; By comparing the text of the text area with the text of the corresponding area of the original image, it is possible to detect a deformed text among the texts in the text area, and based on the deformed text, a unique device capable of identifying a user device It may include an information detection unit for detecting a user code that is a binary code.

The information detection unit may detect the user code based on matching a first value to a deformed text line among text lines in the text area. The information detection unit may detect the user code based on matching a first value to text containing the most consonants or vowels in the text area.

On the other hand, in order to achieve another object of the present invention described above, the present invention provides a digital document protection system in another aspect. The digital document protection system detects a text area from a digital document, detects at least one text to be transformed among texts in the text area based on a user code that is a unique binary code, and is unique to a user device. A watermark embedding device for modifying the at least one text detected based on a user code that is a binary code; And a watermark detection device detecting the user code from an image of a digital document in which the at least one text is modified by the watermark insertion device.

As described above, according to the present invention, text displayed in a digital document can be modified using a unique and simple algorithm based on a user code associated with a user device when displaying a digital document. Therefore, by easily inserting a text modification type watermark into a document, any user device using a watermark inserted in the form of a modified text when a digital document is later leaked through photographing, printing, or screen capture, etc. Can easily determine if a digital document has been leaked.

1 is an exemplary view for explaining a system for realizing a watermark embedding method according to a preferred embodiment of the present invention.
2 is a block diagram showing the configuration of a watermark embedding apparatus according to a preferred embodiment of the present invention.
3 is a block diagram showing the configuration of a text processing unit shown in FIG. 2.
4 is an exemplary view for explaining an example in which the font size of a specific text of a digital document is reduced by the first text processing unit.
5 is an exemplary view for explaining an example in which the text thickness of the text including the most consonants is reduced by the second text processing unit.
6 is a flowchart illustrating a flow of a watermark embedding method according to a preferred embodiment of the present invention.
7 is a flow chart for explaining the flow of the first text processing performed by the watermark embedding device.
8 is a flowchart for explaining the flow of second text processing performed by the watermark embedding apparatus.
9 is a block diagram showing the structure of a watermark detection apparatus according to a preferred embodiment of the present invention.
10 is a flowchart for explaining an operation flow of the information detection unit 230 shown in FIG. 9.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. The term and / or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be 'connected' or 'connected' to another component, it is understood that other components may be directly connected to or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is said to be 'directly connected' or 'directly connected' to another component, it should be understood that no other component exists in the middle.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as 'include' or 'have' are intended to indicate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, and that one or more other features are present. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms, such as those defined in a commonly used dictionary, should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the overall understanding in describing the present invention, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted.

1 is an exemplary view for explaining a system for realizing a watermark embedding method according to a preferred embodiment of the present invention.

As shown in FIG. 1, the watermark embedding system 1 includes a watermark embedding device 100 and a plurality of user devices interworking with the watermark embedding device 100, such as a first user device 10, a first It may include a 2 user device 20 and a third user device 30. The number of user devices may be N (N is 1 natural number).

The watermark generation system 1 may be implemented through an environment in which a server providing a digital document and a plurality of clients accessing the server and using the digital document are provided. For example, the watermark system 1 can be easily implemented in an environment in which a company server and a plurality of employee terminal devices interworking with the server are provided. In this case, the watermark insertion device 100 may correspond to a company's server, and a plurality of user devices may correspond to a plurality of employee terminal devices.

Each user device may access the watermark embedding device 100 and request a digital document, such as an MS-word document, an Excel document, a PowerPoint document, and a Hangul document. Then, the watermark embedding apparatus 100 may convert the requested digital document into a secure digital document embedding a watermark of a text or image conversion format based on a user code and provide the digital document to the requested user device. Each user device is equipped with a security viewer capable of displaying secure digital documents that are allowed for each of them.

For example, the first user device 10 may access the watermark embedding device 100 and request an MS-word document having a file extension of “.doc”. In this case, the watermark embedding device 100 may convert the MS-word document into a secure digital document in which text or images are modified according to the user code of the first user device 100 and transmit the converted text-image to the first user device 10. have. The secure digital document has a predetermined file extension so that it can be recognized as a secure digital document, for example, ".mark".

The security viewer of the first user device 10 may display a secure digital document transmitted from the watermark embedding device 100. At this time, the displayed secure digital document is modified with text or an image so that it can be determined that the document is leaked from the first user device 10 when the document is leaked through picture taking, screen capture, printing, or the like. Of course, such variations of text or images are hardly noticeable by humans.

Since the secure digital document is a watermarked document based on the user code of the first user device 10, access from other user devices, for example, the second user device 20 or the third user device 30 is blocked. Will be. For example, the secure digital document can be played in the security viewer of the first user device 10, but playback is blocked in the security viewer of the second user device 20 or the security viewer of the third user device 30. It may be. Also, playback of the secure document through a general viewer may be blocked.

Meanwhile, according to another embodiment of the present invention, the watermark embedding device may be implemented through each user device. For example, the user device has a watermark insertion module and a viewer, and when a user requests display of a digital document stored in the user device or an external storage, a secure digital document is generated and displayed based on the user code of the user device. You can. That is, if the embodiment as shown in FIG. 1 has a structure more suitable for a server-client environment, the above-described other embodiments may be a structure suitable for an environment where a device is provided alone.

2 is a block diagram showing the configuration of a watermark embedding apparatus 100 according to a preferred embodiment of the present invention.

As shown in FIG. 2, the watermark embedding device 100 includes a user code generation unit 110, an area detection unit 120, a processing unit 140, a file conversion unit 160, and a file transmission unit 170. It can contain. Each of the above parts can be interlocked.

The user code generation unit 110 may generate a user code corresponding to a user device requesting a digital document. The user device may be, for example, any one of the first user device, the second user device, or the third user device illustrated in FIG. 1.

The user code may be a unique binary code (eg, bit string) corresponding to the user device. For example, the user code may be a unique key of the security viewer provided in the user device. The security viewer installed on the user device is assigned a unique key designated from a server providing the security viewer.

When the request for requesting the digital document is received from the user device for displaying the digital document, the user code generation unit 110 may request and receive the unique key value of the security viewer of the user device to the user device. . Alternatively, the unique key value of the security viewer may be included in the request for requesting the digital document and transmitted to the user code generator 110.

The unique key value of the security viewer may or may not be binary code. If the unique key value of the security viewer is binary code, the user code generator 110 may designate the unique key value of the security viewer received from the user device as a user code. On the other hand, if the unique key value of the security viewer is not binary code, the user code generation unit 110 based on the unique key value of the security viewer received from the user device according to a predetermined algorithm, the unique key value of the security viewer It can generate binary code corresponding to.

Meanwhile, the user code may be generated based on at least one of a unique key of the security viewer of the user device, physical identification information of the user device, and user identification information. Here, the physical identification information may be, for example, a MAC (Media Access Control) value. The user identification information may be system information of a user device, login information, and the like.

The user code generation unit 110 may request and receive information necessary for generating a user code to a user device in order to generate a user code reflecting these complex elements. The information required to generate the user code may be at least one of a unique key of the security viewer of the user device, physical identification information of the user device, and user identification information. The user code generator 110 may generate a user code that is a unique binary code corresponding to the user device according to a predetermined algorithm based on the received information.

The area detection unit 120 may respectively detect a text area and an image area from a digital document requested by the user device. The text area means an area containing text. The image area may be an area including an image, or may be an area other than the text area in the digital document.

The processing unit may insert text and image modification type watermarks into the digital document by modifying the text of the text area and the image of the image area detected by the area detection unit 120 based on a user code, respectively. . The processing unit 130 may include a text processing unit 140 and an image processing unit 150.

The text processing unit 140 detects at least one text to be transformed among texts in the text area based on the user code generated by the user code generation unit 110, and based on the user code A function of modifying the detected at least one text may be performed.

FIG. 3 is a block diagram showing the configuration of the text processing unit 140 shown in FIG. 2.

As shown in FIG. 3, the text processing unit 140 may include a first text processing unit 142 and a second text processing unit 145. The first text processing unit 142 may include a first text detection unit 143 and a first watermark insertion unit 144. The second text processing unit 145 may include a second text detection unit 146 and a second watermark insertion unit 147.

The operation sequence of the first text processing unit 142 and the second text processing unit 145 of the text processing unit 140 is processed by the first text processing unit 142 after the first text processing unit 142 operates first. The text of the text area may be processed by the second text processing unit 145, or the text of the text area processed by the second text processing unit 145 may be processed by the second text processing unit 145 first. The processing unit 142 may also process.

The first text detection unit 143 may detect a text line to be transformed among text lines in a text area based on a user code. For example, the first text detection unit 143 may sequentially associate each text line in the text area with each bit value of the user code. Here, each bit value of the user code may be either a first value or a second value. The first text detection unit 143 may detect a text line whose corresponding bit is the first value. The first value may be "1" and the second value may be "0". That is, the first text detection unit 143 may detect a text line having a corresponding bit value of "1" among the text lines. Meanwhile, it is needless to say that the first value and the second value may be “0” and “1”, respectively, depending on the implementation environment.

The first watermark insertion unit 144 may reduce the font size of the text included in the text line detected by the first text detection unit 143 by a set size. For example, the first text detection unit 143 may reduce the font size of text included in the detected text line to “1 Pt”. Preferably, the reduction of the font size is assumed to be a fine degree that is difficult for humans to perceive.

4 is an exemplary view for explaining an example in which the font size of a specific text of a digital document is reduced by the first text processing unit 142.

As shown in Fig. 4, it is assumed that the user code is "10011" and the text in the text area of the digital document is "12Pt". In addition, it is assumed that the first value is "1" and the second value is "0" in the bit value of the user code.

In this case, the first text detection unit 143 corresponds to the first text line of the text area corresponding to the first code "1" of the user code, and the second text line of the text area to the second code of the user code "0" ", The third text line of the text area to the third code" 0 "of the user code, the fourth text line of the text area to the fourth code" 1 "of the user code, The fifth text line of the area may correspond to the fifth code "1" of the user code.

The first text detection unit 143 may detect the first, fourth, and fifth text lines having a corresponding bit value of "1" among the five text lines as text lines to reduce the font size. Then, the first watermark inserting unit 144 reduces the font size of the first, fourth, and fifth text lines by a preset reduction size of "1". Therefore, the font size of the first, fourth, and fifth text lines is reduced to "11Pt". Needless to say, the second and third lines where the font size is not reduced remain "12Pt".

On the other hand, the first text detection unit 143 may correspond to a bit value of the user code, only some predetermined text lines among text lines in the text area. For example, if the first text detection unit 143 has 10 text lines in the text area and the bit value of the user code is "10011", each bit value of the user code from the fifth text line to the ninth text line Can be matched sequentially.

Also, the first text detection unit 143 may sequentially match the bit values of the user code to text lines in the text area. For example, when the bit value of the user code is “10011”, the first text detection unit 143 sets each bit value of “10011” from a specific text line in the text area, for example, from the first text line to the fifth text line. The bit values of "10011" may be sequentially matched from the sixth text line to the tenth text line.

On the other hand, when the bit values of the user code are sequentially repeated to correspond to the text lines in the text area, the first text detection unit 143 may insert a specific bit value between the repeated user codes. For example, when the bit value of the user code is “10011”, the first text detection unit 143 sets each bit value of “10011” from a specific text line in the text area, for example, from the first text line to the fifth text line. Sequentially, the default value "0" may be associated with the sixth text line, and each bit value of "10011" may be sequentially associated with the seventh text line to the eleventh text line.

The second text detection unit 146 detects the most consonants or vowels included in the texts included in the text area, and converts the text to be transformed among the texts including the detected consonants or vowels based on a user code. It can also be detected. For example, the second text detection unit 146 detects the largest number of consonants or vowels included in the texts included in the text area, and recalls each text including the detected consonants or vowels in the text area. After sequentially matching each bit value of the user code, it is possible to detect that the text corresponding to the first bit is the text to be transformed.

The second watermark insertion unit 147 may reduce the text thickness of the text detected by the second text detection unit 146 by a preset thickness. Preferably, the reduction in the thickness of the text is assumed to be a degree that is fine enough for a human to not recognize.

5 is an exemplary view for explaining an example in which the text thickness of the text including the most consonants is reduced by the second text processing unit 145.

As illustrated in FIG. 5, the second text detection unit 146 may detect that the most consonant present in the text area is “a (memory)”. The second text detection unit 146 includes the texts including the "a", such as "a" of the first text line, "persimmon" of the second text line, "kim" and "phrase" of the third text line, In the fourth text line, "10011" is sequentially associated with "light". The second text detection unit 146, among the texts, has a bit value of a corresponding user code as a first value, for example, "A" of the first text line with "1", "Spherical" of the third text line, and the fourth text It can be detected as the text to change the "diameter" of the line. Then, the second watermark processing unit may reduce the text thickness of the texts detected as being the text to be changed by a preset thickness.

On the other hand, the second text detection unit 146 may correspond to the bit value of the user code only to a predetermined predetermined text among texts including the most existing consonants or vowels. For example, in the second text detection unit 146, if there are 10 texts including the most existing consonants or vowels, and the bit value of the user code is “10011”, the user code is from the fifth text to the ninth text. Each bit value of can be mapped sequentially.

Also, the second text detection unit 146 may sequentially repeat the bit values of the user code to the texts including the most existing consonants or vowels. For example, when the bit value of the user code is "10011", the second text detection unit 146 selects a specific text among ten texts including the most existing consonants or vowels, for example, the first text to the fifth text. Up to each bit value of "10011" may be sequentially matched, and each bit value of "10011" may be sequentially mapped from the sixth text to the tenth text.

On the other hand, when the bit values of the user code are sequentially repeated to correspond to the texts containing the most existing consonants or vowels, the second text detection unit 146 inserts a specific bit value between the repeated user codes. It might be. For example, when the bit value of the user code is "10011", the second text detection unit 146 selects a specific text among texts including the most existing consonants or vowels, for example, from the first text to the fifth text. " Each bit value of 10011 "may be sequentially associated, the default value of" 0 "may be associated with the sixth text, and each bit value of" 10011 "may be sequentially associated with the seventh text to the eleventh text.

Meanwhile, in the embodiment with reference to FIG. 3, the first text processing unit 142 reduces the font size of the text, and the second text processing unit 145 reduces the font thickness of the text, but this is not a limitation. In another embodiment of the present invention, the first text processing unit 142 may reduce the font thickness and the second text processing unit 145 may reduce the font size. For example, the first watermark embedding unit 144 of the first text processing unit 142 may reduce the text thickness of the text in the text line detected by the first text detecting unit 143. The second watermark insertion unit 147 of the second text processing unit 145 may reduce the font size of the texts detected by the second text detection unit 146 by a set amount.

As described above, the text deformed by the first text processing unit 142 and the second text processing unit 145 is slightly reduced compared to the text before modification, so that no text overflow occurs due to text transformation.

Meanwhile, according to another embodiment of the present invention, the text processing unit 140 may include only the first text processing unit 142 or only the second text processing unit 145. That is, the text processing unit 140 according to the present invention may include at least one of the first text processing unit 142 and the second text processing unit 145.

Referring back to FIG. 2, the image processing unit 150 may transform the image of the image region detected by the region detection unit 120 based on the user code. For example, the image processing unit 150 divides the image in the image area into detailed pieces of a predetermined size, for example, cells, and based on the user code, calculations performed on the divided detailed pieces, such as exclusive ore The (XOR) operation can be used to insert the user code.

The image processing unit 150 may use the user code used by the text processing unit 140, or may use the user code for image conversion separately generated by the user code generation unit 110. In the latter case, it may be generated based on information such as the author information and the creation date of the digital document, as well as the elements described above.

The file conversion unit 160 displays the file extension of the digital document (ie, the digital document with the watermark inserted) in which the text in the text area and the image in the image area are respectively modified by the text processing unit 140 and the image processing unit 150. It can be converted to a file extension of a predetermined format. For example, if the file extension of the requested digital document is ".doc", the file conversion unit 160 may change the extension of the digital document to a file extension such as ".mark". Therefore, a person can visually determine that the requested digital document is a secure digital document with a watermark embedded therein.

The file transfer unit 170 may transmit the secure digital document whose file extension is changed by the file conversion unit 160 to the requested user device. The user device may display the secure digital document using a security viewer provided in the user device. The text and image of the displayed secure document are modified based on user information corresponding to the user device by the watermark insertion device. However, variations in text and images are difficult to discern.

Meanwhile, since the secure digital document is a document in which text and images are modified based on a user code corresponding to the user device, the secure digital document can be displayed by a predetermined security viewer provided in the user device. Access from user devices may be blocked. For example, the display by the security viewer or the general viewer provided in the secure digital document other user device may be blocked, and the display may also be disallowed by the general viewer provided in the user device.

In the above, the watermark embedding apparatus according to the preferred embodiment of the present invention has been described. Hereinafter, a method of inserting a watermark based on the watermark embedding device will be described.

6 is a flowchart illustrating a flow of a watermark embedding method according to a preferred embodiment of the present invention.

First, the user device may access the watermark embedding device and display a list of digital documents that can be provided by the watermark embedding device. The user device may be, for example, any one of the first user device, the second user device, and the third user device shown in FIG. 1. When the user selects a desired digital document, the user device may request the digital document to the watermark embedding device to display the selected digital document. Then, the procedure of the watermark embedding device is started.

6, first, the watermark embedding device may generate a user code corresponding to the user device (step: S1). As mentioned above, the user code is a unique binary code corresponding to the user device, based on at least one of a unique key of the security viewer of the user device, physical identification information of the user device, and user identification information. Can be created.

For the generation of the user code, for example, the watermark embedding device may receive information necessary for generation of the user code by the user device in a pull or push method. The information required to generate the user code may be at least one of a unique key of the security viewer of the user device, physical identification information of the user device, and user identification information. The watermark embedding device may generate a user code that is a unique binary code corresponding to the user device according to a predetermined algorithm based on the received information.

Subsequently, the watermark embedding device may detect the text area and the image area respectively from the digital document requested by the user device (step: S2). The text area means an area containing text. The image area may be an area including an image, or may be an area other than the text area in the digital document.

When the text area is detected, the watermark embedding device may perform text processing based on the user code (step: S3). For example, the apparatus for inserting a watermark may detect at least one text to be transformed among texts in the text area, and transform the detected at least one text based on the user code.

More specifically, in step S3, the watermark insertion device may perform first text processing and second text processing. The watermark embedding device may perform first text processing first, then second text processing, or second text processing and then first text processing.

7 is a flow chart for explaining the flow of the first text processing performed by the watermark embedding device.

As shown in FIG. 7, the watermark embedding apparatus may detect a text line to be transformed among text lines in a text area based on a user code (step: S11). For example, the watermark embedding apparatus may sequentially associate each text line in the text area with each bit value of the user code. Here, each bit value of the user code may be either a first value or a second value. The first text detection unit 143 may detect a text line whose corresponding bit is the first value. The first value may be "1" and the second value may be "0". That is, the watermark embedding apparatus can detect a text line having a corresponding bit value of "1" among the text lines.

Subsequently, the watermark embedding apparatus may reduce the font size of the text included in the detected text line by a set size (step: S12). For example, the watermark embedding apparatus may reduce the font size of text included in the detected text line to "1 Pt". Preferably, the reduction of the font size is assumed to be a fine degree that is difficult for humans to perceive.

On the other hand, as mentioned above, according to another embodiment of the present invention, after performing the step S11, the watermark embedding apparatus reduces the text thickness of the text included in the detected text line by a preset amount instead of the step S12. You may.

8 is a flowchart for explaining the flow of second text processing performed by the watermark embedding apparatus. In the example shown in FIG. 8, it is assumed that the most consonants are detected in the text area.

As shown in FIG. 8, the watermark embedding apparatus can detect the most consonants in the text area (step: S21). Subsequently, the watermark embedding apparatus may detect the text to be modified among the texts including the detected consonants based on the user code (step: S22). For example, the watermark embedding apparatus sequentially matches each text containing the detected consonant present in the text area to each bit value of the user code, and then transforms the text whose corresponding bit is the first value. It can be detected as text.

Next, the watermark insertion device may reduce the text thickness of the detected text by a set thickness (step: S23). Preferably, the reduction in the thickness of the text is assumed to be a degree that is fine enough for a human to not recognize. On the other hand, according to another embodiment of the present invention, the watermark embedding apparatus may reduce the font size of the detected text by a preset amount instead of the step S23 after performing the step: S22.

According to another embodiment of the present invention, the text processing step may perform only the first text processing or only the second text processing. That is, the text processing step according to the present invention may perform at least one of first text processing and second text processing.

Meanwhile, when the image area is detected, the watermark embedding device may perform image processing for transforming the image of the detected image area based on a user code (step: S4). For example, the watermark embedding apparatus divides an image in an image area into detailed pieces of a predetermined size, for example, cells, and based on the user code, calculations performed on the divided detailed pieces, such as exclusive or ( XOR) operation to insert the user code.

Next, the watermark embedding device uses a file extension of a digital document (that is, a digital document in which a watermark is inserted), each of which transforms the text in the text area and the image in the image area, based on the user code. Can be converted (step: S5). For example, if the file extension of the requested digital document is ".doc", the watermark embedding device may change the extension of the digital document to a file extension such as ".mark". Therefore, a person can visually determine that the requested digital document is a secure digital document with a watermark embedded therein.

The watermark embedding device may transmit a secure digital document converted with a file extension to the requesting user device. The user device can display the secure digital document using a secure viewer. The text and image of the displayed secure document are modified based on user information corresponding to the user device by the watermark insertion device. However, variations in text and images are difficult to discern.

Meanwhile, since the secure digital document is a document in which text and images are modified based on a user code corresponding to the user device, the secure digital document can be displayed by a predetermined security viewer provided in the user device. Access from user devices may be blocked. For example, the display by the security viewer or the general viewer provided in the secure digital document other user device may be blocked, and the display may also be disallowed by the general viewer provided in the user device.

On the other hand, the secure digital document displayed by the user device may be illegally leaked by a person who has an unintended intention by photographing, screen capturing, or printing. At this time, if an image of the leaked security digital document is obtained, it is possible to find out from which user device the security digital document has been leaked based on a watermark embedded in the security digital document. This can be done by a watermark detection device.

9 is a block diagram showing the structure of a watermark detection apparatus according to a preferred embodiment of the present invention.

As illustrated in FIG. 9, the watermark detection apparatus 200 may include a digital document image acquisition unit 210, an area detection unit 220, an information detection unit 230, and the like.

The digital document image acquisition unit 210 may acquire an image of a secure digital document in which a watermark is inserted by the watermark insertion device 200. As described above, in the secure digital document, text and images in a text area and an image area are modified based on a user code.

The area detection unit 220 may respectively detect a text area and an image area from the secure digital document image acquired by the digital document image acquisition unit 210. The text area means an area containing text. The image area may be an area including an image, or may be an area other than the text area in the digital document.

The information detection unit 230 may perform a function of decoding a watermark of a text modification type inserted in the text area detected by the area detection unit 220 to detect a user code. 10 is a flowchart for explaining an operation flow of the information detection unit 230 shown in FIG. 9.

10, the information detection unit 230 compares the text of the text area detected by the area detection unit 220 with the text of the corresponding area of the original image (step: S31), and based on the comparison By doing so, it is possible to detect a deformed text among texts in the text area (step: S32). The information detection unit 230 may detect a user code that is a unique binary code that can identify a user device based on the modified text (step: S33).

9, the information detection unit 230 may include a first information detection unit and a second information detection unit of the information detection unit 230.

The first information detection unit 231 stores and manages the processing algorithm of the first text processing unit 142 of the watermark embedding device in advance. The first information detection unit 231 may detect a user code by inverting the processing algorithm of the first text processing unit 142. For example, the first information detector 231 compares the text of the detected text area with the text of the corresponding area of the original image, and based on the comparison, changes the text line among the text lines in the text area. After detection, the user code can be detected by matching the first value to the deformed text line.

The second information detection unit 233 stores and manages the processing algorithm of the second text processing unit 145 of the watermark embedding device in advance. The second information detection unit 233 may detect the user code by inverting the processing algorithm of the second text processing unit 145. For example, the second information detection unit 233 compares the text of the detected text area with the text of the corresponding area of the original image, detects deformed texts based on the comparison, and simulates the text within the text area. Based on matching a first value to text containing many consonants or vowels, the user code can be detected.

The preferred embodiments of the present invention have been exemplified and described, but those skilled in the art variously modify and change the present invention without departing from the technical details and scope of the present invention as set forth in the claims below. You can understand that you can do it. Therefore, changes in the embodiments of the present invention will not be able to escape the technology of the present invention.

100: watermark insertion device
110: user code generator
120: area detection unit
130: processing unit
140: text processing unit
150: image processing unit
160: file converter
170: file transfer unit

Claims (29)

It is performed by the watermark insertion device,
Detecting a text area from a digital document;
Detecting at least one text to be transformed among texts in the text area based on a user code that is a unique binary code corresponding to a user device; And
And transforming the detected at least one text based on the user code.
The detecting of the at least one text may include:
And detecting a text line to be transformed among text lines in the text area based on the user code.
The detecting of the text line to be transformed may include:
Each line of text in the text area is sequentially repeated to correspond to each bit value of the user code, and inserting a specific bit value between repeated user codes; And
And detecting a text line whose corresponding bit is a first value.
The method of claim 1, wherein the user code is generated based on at least one of a unique key of a security viewer provided on the user device, physical identification information of the user device, and user identification information corresponding to the user device. Watermark embedding method further comprising the step of.
The method of claim 1, further comprising: receiving a request for the digital document from the user device;
Requesting information necessary for generating the user code to the user device; And
And receiving information necessary for generating the user code from the user device.
According to claim 1, The step of transforming the at least one text,
And reducing the font size of the text in the detected text line or reducing the thickness of the text.
delete delete delete The method of claim 1, further comprising: detecting an image area from the digital document;
Dividing the detected image of the image area into predetermined detailed pieces; And
And adding a predetermined operation to the divided detailed pieces based on the user code.
The method of claim 8, wherein the step of applying the predetermined operation,
Generating a bit stream based on the user code; And
And inserting the bit stream using an exclusive OR (XOR) operation on the divided detail piece.
The method of claim 1, further comprising: converting a file extension of the digital document in which the at least one text is modified into a predetermined extension; And
And transmitting the digital document converted to the predetermined extension to the user device,
The digital document transmitted to the user device is displayed by a predetermined security viewer provided on the user device, and access from a general viewer and other user devices is blocked.
An area detection unit that detects a text area from a digital document; And
Based on the user code, which is a unique binary code corresponding to a user device, at least one text to be modified among the texts in the text area is detected, and based on the user code, which is a unique binary code, the detected at least It includes a text processing unit for transforming one text,
The text processing unit,
Each text line in the text area is sequentially repeated to correspond to each bit value of the user code, but inserting a specific bit value between repeated user codes, and detecting a text line whose corresponding bit is the first value. Watermark insertion device characterized in that.
The user code of claim 11, based on at least one of a unique key of the security viewer provided on the user device, physical identification information of the user device, and user identification information corresponding to the user device. Watermark embedding apparatus further comprising a code generator.
The method of claim 11, further comprising: receiving a request for requesting the digital document from the user device, requesting information necessary for generating the user code to the user device, and receiving information necessary for generating the user code from the user device The apparatus for inserting a watermark, further comprising a receiving user code generator.
The method of claim 11, wherein the text processing unit,
Watermark embedding apparatus, characterized in that to reduce the font size of the text in the detected text line or to reduce the text thickness.
delete delete delete 12. The method of claim 11, wherein an image area is detected from the digital document, an image of the detected image area is divided into predetermined detailed pieces, and a predetermined operation is applied to the divided detailed pieces based on the user code. Watermark embedding apparatus further comprising an image processing unit.
The image processing unit of claim 18,
And generating a bit stream based on the user code, and inserting the bit stream using an exclusive OR (XOR) operation on the divided detail piece.
12. The system of claim 11, further comprising: a conversion unit that converts a file extension of the digital document in which the at least one text is modified into a predetermined extension; And
Further comprising a transmission unit for transmitting the digital document converted to the predetermined extension to the user device,
The digital document transmitted to the user device is displayed by a predetermined security viewer provided on the user device, and access from a general viewer and other user devices is blocked.
A user device requesting a digital document over a network; And
A text area is detected from the digital document, and at least one text to be transformed among texts in the text area is detected based on a user code that is a unique binary code corresponding to the user device. And a watermark embedding device for transforming the detected at least one text,
The watermark insertion device,
Each text line in the text area is sequentially repeated to correspond to each bit value of the user code, but inserting a specific bit value between repeated user codes, and detecting a text line whose corresponding bit is the first value. Watermark embedding system. delete delete delete delete delete delete delete delete

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