KR200249617Y1 - Off-line detector using digital watermark - Google Patents

Abstract

The present invention relates to an off-line detector for judging whether a document is forged or forged by altering or copying an output copy of a document in which a watermark for original authentication is inserted.

The offline detector of the present invention includes an A / D conversion unit for converting a document recognized through an optical device into a digital image; A watermark detection unit extracting an embedded watermark from the converted digital image to detect information; A user input unit where a user inputs predetermined information about a document; And a comparison unit comparing the information input by the user input unit with the information detected by the watermark detection unit to determine whether the document is forged or forged.

With such a configuration, it is possible to directly determine whether the document is forged / modified in a short time on the offline of the printed copy of the document in which the watermark is inserted online.

Description

OFF-LINE DETECTOR USING DIGITAL WATERMARK}

The present invention relates to an off-line detector using digital watermarking, and more specifically, to determine whether a forgery or forgery of a document is changed off-line through alteration and copy of an output copy of a document having a watermark for original authentication. For an offline detector.

As a conventional technique for determining whether a forgery / falsification of various documents including gift certificates, various tickets, bonds, notes, lotteries, etc.

1) how to use special paper, such as the use of silver paper, the use of ready-made patterns, or the use of OMR paper,

2) design methods such as the application of holograms, anti-copy or light interference patterns, or flat or latent images;

3) using special inks such as fluorescence technique, use of uneven printing ink or use of thermochromic ink, and

4) There are special printing techniques such as negative printing, rainbow printing or barcode printing, and these are filed by the applicant on January 12, 2001, and the title of the invention is 'securities using digital watermarking'. Issuance, authentication apparatus and method 'Korean Patent Application No. 2001-0001940, the invention is incorporated herein by reference.

However, such a document forgery / forgery discrimination technique can not be authentic authentication of the document by applying the same algorithm to the document using the plain paper. Therefore, the problem that the manufacturing cost is relatively high and the determination of forgery and / or forgery have a problem in that the determination apparatus and the determination method are different according to each of the above methods, and thus uniform determination is not made.

On the other hand, with the development of digital technology, many digital works of various forms are being authored. Such digital works can be reproduced indefinitely without damaging the original, and since the copy and the original are difficult to distinguish, illegal copying and illegal distribution are indiscriminate.

There is a digital watermarking method as a method for preventing illegal copying and forgery / falsification of digital works (ie, digital contents). Digital watermarking is a technology that inserts certain data (ie, watermarks) to be claimed, such as copyright information, into multimedia content such as audio, video, images, or text indistinguishable from the human eye or hearing. If the original owner needs to be identified, such as a dispute of ownership, in the distribution process of digital content, the inserted watermark is detected to provide a basis for exercising the rights such as ownership and copyright.

Digital watermarking has the advantage of protecting copyright information by concealing and inserting information about the content without the user's knowledge, but it has been mainly considered only in terms of software to protect digital content online. It has not been considered to judge the forgery / modulation of the output document after the digital content is output off-line.

Also, in recent years, gift certificates, tickets, and civil complaints are all produced in the form of digital files. It is necessary to be able to determine whether or not.

The present invention aims to solve the problems described above, and an object of the present invention is to reduce costs by not using the complicated special technique for preventing forgery / falsification of documents, and to print watermarks inserted online. It is to provide an offline detector that can directly determine whether a document is forged or forged.

Another object of the present invention is to obtain a ticket or a complaint form in the form of a digital file through the Internet or online, and then print it on a general paper so that it can be checked off-line directly at the place of use. It is to provide an offline detector that can solve the time loss and inconvenience that the buyer has to wait for a long time.

1 is a block diagram schematically illustrating a system configuration of an offline detector according to the present invention.

FIG. 2 is a flowchart illustrating an operation of the offline detector of FIG. 1.

Explanation of symbols on the main parts of the drawings

100: off-line detector 110: A / D conversion unit

120: image processing unit 130: motor control unit

140: user interface unit 142: input device

144: result display unit 150: document recognition unit

160: watermark detection unit 170: main control and comparison unit

180: PC interface unit 190: program memory unit

200: work memory / image processing memory

210: data backup unit 220: power supply device

In order to achieve the above object, the present invention is an off-line detector for judging whether or not forgery / modulation of a printed document by inserting a watermark online, and converting a document recognized through an optical device into a digital image. / D conversion unit; A watermark detection unit extracting an embedded watermark from the converted digital image to detect information; A user input unit where a user inputs predetermined information about a document; And a comparing unit comparing the information input by the user input unit with the information detected by the watermark detection unit to determine whether the document is forged or forged.

In addition, the offline detector preferably further includes a result display unit for displaying the result of the forgery / forgery determination of the document in the comparison unit.

The off-line detector may further include an image processing unit which performs one or more of noise reduction of the digital image converted by the A / D converter, detection of contours for character recognition, low pass / high pass filtering, and region extraction.

Herein, the predetermined information input by the user in the user input unit is information about a high forgery / falsification part of the document, and the predetermined information is inserted into the document as a watermark when the document is issued. desirable.

Here, it is preferable that the inserted watermark is generated by a key generation method, a logo method, or both.

Here, the embedded watermark is preferably a strong watermark or a fragile watermark, or both.

Here, the inserted watermark is preferably an optical watermark using a light interference phenomenon or a surface latent phenomenon.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

First, a hardware configuration of the off-line detector using digital watermarking according to the present invention will be described. 1 is a block diagram schematically showing a system configuration of an offline detector 100 according to the present invention.

Referring to FIG. 1, the offline detector 100 according to the present invention includes a digital image information obtained from the A / D converter 110 and the photoelectric converter 110 for converting an analog signal into a digital signal. 150) and an image processor 120 to facilitate processing by the watermark detection unit 160, a motor controller 130 to insert a document to drive the optical device, and a person who uses the offline detector 100 to input information. And a user interface unit 140 for viewing the results, a document recognition unit 150 for automatically recognizing the contents of the document converted into a digital signal, a watermark detection unit 160 for detecting a watermark included in the document, offline detector The main control and comparison unit 170, the PC interface unit 180, the program memory unit 190, the working memory / image processing memory unit 200, which controls all functions of the 100 and compares and determines the authenticity of documents. , A data backup unit 210 and a power supply device 220.

The A / D converter 110 converts a watermarked offline document output after the watermark is inserted online into a digital electronic signal (ie, a digitized image) by using an optical device. Performs the function of converting to a signal. Here, the optical device may have the same configuration as that of a digital camera or scanner, and is composed of a part for generating light and a lens for recognizing an image by illuminating and enlarging it on a document.

The image processing unit 120 performs a function of facilitating processing of the digitized image obtained by the A / D conversion unit 110 by the document recognition unit 150 and the watermark detection unit 160 described later. Examples of such functions include noise removal during A / D conversion, contour detection for character recognition, thinning algorithms, low and high pass filtering, and region extraction algorithms.

The motor control unit 130 is a part for controlling the motor for driving the optical device to read the output document on the offline with the optical device. That is, when the output document is input to the offline detector 100 in order to convert the output document into an electronic signal through an optical device, a motor necessary for rotating the roller equipped with a tooth to insert the document in the same shape as the roller The part that controls. In addition, when using an optical device, such as a scanner, the optical device portion and the light source must pass through the output document in order to read the output document, it may be a portion for controlling the motor for driving the output document.

The user interface unit 140 includes an input unit 142 and a result display unit 144. The input unit 142 is a person who uses the offline detector 100 (that is, a person who wants to determine the authenticity of the document) to determine the authenticity of the document using, for example, a keyboard, an electronic pen, a mouse, a scanner, and a barcode input device. It performs a function of inputting necessary information, which will be described in detail later with reference to FIG. 2. The result display unit 144 may be, for example, an LCD, an LED, a CRT monitor, or the like. The result display unit 144 displays a determination result regarding whether the document is forged or forged.

The document recognizing unit 150 is a part for automatically recognizing the contents of the document from the digitized image of the document for which authenticity is to be determined. This includes the character recognition algorithm, which automatically recognizes the important contents of the document using the character recognition algorithm.

The watermark detection unit 160 detects a watermark included in a document converted into a digitized image. The watermark is embedded in the document online so that the document is printed and then input to the offline detector 100. The watermark detection unit 160 that detects the watermark as described above will be described in more detail in the description with reference to FIG. 2 described later.

The main control and comparison unit 170 collectively controls the functions of the other components of the offline detector 100, and also provides information on the watermark detected by the watermark detection unit 160 and an input unit of the user interface unit 140. In step 142, the input information is judged to be consistent to determine whether the document is forged or forged. In addition, the determination result also performs a function to be displayed on the result display unit 144 of the user interface unit 140.

The PC interface unit 180 enables the digital image information obtained from the A / D conversion unit 110 to be confirmed through a PC, and transmits the document forgery / modulation determination result of the offline detector 100 to be stored in the PC. Do it. It is also used to perform a program upgrade of the offline detector 100. As a PC interface method, serial port (RS232C), USB, parallel port and SCSI method, and downloading through the Internet or LAN, wired or wireless device such as PDA or mobile phone can be used.

When such a PC interface unit 180 is required, the offline detector 100 is a stand-alone type similar to a scanner, not an integrated type with a PC including the functions of a PC. That is, when the offline detector 100 is an integrated type including the functions of a PC, the PC interface unit 180 is not particularly required.

The program memory unit 190 is a portion in which an operation program of the offline detector 100 is located, and refers to a memory in which a program for operating the offline detector 100 and detecting a watermark is entered. The program memory unit 190 is a nonvolatile memory and is maintained even if the power supply is cut off.

The work memory / image processing memory unit 200 is a memory unit in which an image (that is, a digitized image) is stored and processed and various operations are performed, and the information contained in the memory disappears when power is not supplied. In this way, even if the accumulation of continuous work does not affect the product.

Similar to the program memory unit 190, the data backup unit 210 has a nonvolatile characteristic that information is maintained even without a power supply. As a result, the processing result of the offline detector 100 can be stored for a long time.

The power supply 220 performs a function of changing the commercial power (AC 220V / 110V) into a power available in the offline detector 100.

Next, a hardware configuration of the off-line detector using digital watermarking according to the present invention will be described. 2 is a flowchart illustrating an operation of the offline detector 100 of FIG. 1.

First, input the document to determine whether the forgery / forgery in the offline detector (100) (S300). That is, the document is read through the optical device under the control of the motor control unit 130. Here, the input document is a document output to the printer after the watermark is inserted online. For example, it may be an embodiment in which a user downloads a ticket or an administrative document including a watermark from the Internet and determines whether the user has forged / modified the document printed on his computer terminal in the offline detector 100. This is disclosed in detail in Korean Patent Application No. 2001-0001940.

The input document is converted into a digital signal (ie, a digitized image) by the A / D converter 110 (S310). The digitized image obtained by the A / D converter 110 removes noise and unnecessary information while the image processor 110 undergoes an image preprocessing process (S320).

Next, the digitized document, which has undergone the image preprocessing process, is automatically recognized by the document recognition unit 150 through the character recognition algorithm (S330). This is a previous step for the extraction of the watermark.

The person who uses the offline detector 100 (that is, the person who wants to judge the authenticity of the document) can use the input unit 142 of the user interface 140 to determine the information (i.e., the portion of the document that is easily forged / modified). Information inserted as a watermark) is input (S340).

That is, for example, if the document is a security, price information, issuance related information, issued user information, and expiration date information may be input using, for example, a keypad. At this point, the user should have a sample of which parts of the document are most likely to be forged / modulated. In other words, the information input by the user is defined in advance according to the contents of the document, and is distributed after inserting the predefined information as a watermark when the document is issued.

Alternatively, the user inputs the original document through the input unit 142 instead of directly inputting such information (of course, the input unit 142 becomes a scanner, etc.), and automatically detects forgery / falsification discrimination information through document recognition. You can also make it aware. Recognition information here includes numbers, Korean / English characters, special characters, symbols, and the like. In this way, the forgery / modulation discrimination information input by the input unit 142 is compared with the watermark detected later and used to determine the authenticity of the document.

The watermark is extracted from the watermark detection unit S350 in the document in which the watermark passed through the document recognition unit 150 is inserted (S350). Herein, the watermark is a watermark generated and inserted by a predetermined method by using the information of the part which is likely to be forged / modulated according to the content of the document when the document is issued.

The watermark insertion and extraction method used in the present invention may be a method using a key method, a logo method, or both at the same time.

A key type watermark is often the same as a key used in encryption, and it inserts a pseudo random number generated from the key as a watermark because there is a key. At this time, the key may be a specific number or text which only the creator knows, and this key is used to extract the watermark in the future. In other words, assuming that the secret watermark inserted as a single cipher is a key for decrypting the cipher.

A logo type watermark is literally a series of images, such as a logo, as a watermark. Since image data can also be represented as a series of digital signals, it becomes a watermarking method that provides much more visible information when extracting by inserting image data such as a logo indicating an issuer in original data.

In addition, the watermark embedding and extraction method used in the present invention may be a method of using a strong watermark or a soft watermark, or both.

The technique of embedding a robust watermark in an attack ensures that the information retained by the inserted signal is preserved as the robust watermark survives the various externally possible attacks. Since the information includes other related contents including the source of the document, etc., it extracts the watermark and verifies the information to authenticate the document and distinguish it from the forgery.

The technique of embedding a fragile watermark allows the watermark to be lost even in the case of fine external manipulations and deformations so that it is possible to clearly distinguish whether or not an external forgery manipulation has been applied. Therefore, it plays a role to disable illegal use of forged documents.

On the other hand, in the present invention, in addition to optical watermarking using optical interference phenomenon or surface latent phenomenon, it is possible to apply. For reference, the optical interference phenomenon is that when the scan or copy is made, the dark part of the refraction wavelength generated on the pattern is folded and the shape is copied as it is being pushed out while constantly shining from one side to the other. Depending on the pattern is a phenomenon that does not appear well visually caused by interference.

Surface latent images are difficult to observe with the naked eye in the process of gluing two sheets of paper together or by adding wires or silver wires, or by using chemicals on plain paper. It is a method and the phenomenon of detecting the contents by physical and chemical methods by hiding the patterns, figures, characters, etc. as if specific characters or patterns are visible when UV light is emitted.

Therefore, when the document is printed, or if there is an illegal act of copying and distributing the document, putting the document in the copy machine and copying it causes an invisible pattern or phrase (such as “COPY”) to appear. This is to prevent the illegal copying of a document by making it known that it is a copy.

Next, the information input from the input unit 142 of the user interface unit 140 and the watermark information extracted from the watermark detection unit 160 are compared by the main control and comparison unit 170 to determine whether the document is forged or forged. It is determined (S360).

For example, when the face value of the originally issued gift certificate is 50,000 won, the face value of the 50,000 won is inserted as a watermark. If, in the course of distribution, the face value is modulated to 100,000 won, the information input through the input unit 142 (that is, the face value of 100,000 won) and the information represented by the watermark extracted from the watermark detection unit 160 (ie, The face value of 50,000 won) is different so that the document can be altered.

In addition, as disclosed in Korean Patent Application No. 2001-0001940, a method of determining whether or not to illegally copy a document by adjusting the insertion strength of a soft watermark may also be used. That is, the insertion strength of the soft watermark is detected only when the first A / D conversion is performed in the printed state, and is not detected when the subsequent A / D or D / A conversion is performed. Then, if there was a copy or scan process (ie, an illegal copying process) before the A / D conversion of the offline detector 100 after the document was issued and printed, the weak watermark is not detected by the offline detector 100. This can determine whether a document is illegally copied.

As such, if it is determined whether the document is forged / falsified or illegally copied, the determination result is displayed to the user through the result display unit 144 of the user interface unit 140 (S370). The operation of the offline detector 100 to determine the operation is terminated. The result display unit 144 can grasp the contents through a monitor-like form, or can easily identify the result display unit 144 of the offline detector by using an LED or the like so as to be visually or audibly distinguished, or forgery and illegality. The sound may be processed at the time of discrimination to make it easier to discriminate.

Although the present invention has been specifically shown and described with reference to the above embodiments, it has been used for the purpose of illustration and those of ordinary skill in the art to which the present invention pertains, as defined in the appended claims and the spirit and scope of the invention. Various modifications can be made without departing.

By using the offline detector of the present invention as described above, it is possible to distribute the documents (online administrative documents, coupons, gift certificates and securities, etc.) issued online without using a special paper. That is, the on-line document issuance can be activated by the off-line offline detector easily detecting the intentional forgery / falsification of the document published online.

In addition, it is not necessary to go to the administrative agency in order to receive various administrative documents, etc., and only by issuing documents online and outputting them through a printer.

In addition, whether or not illegal copying by the copier of the issued document by using the soft watermark with the insertion strength is also determined by the offline detector.

Claims (7)

It is an off-line detector that determines whether the watermark is inserted online and forgery or forgery of the printed document. An A / D converter for converting the document recognized by the optical device into a digital image; A watermark detection unit extracting the inserted watermark from the converted digital image to detect information; A user input unit where a user inputs predetermined information about the document; And And a comparison unit comparing the information input by the user input unit with the information detected by the watermark detection unit to determine whether the document is forged or forged. The method of claim 1, And a result display unit for displaying the result of the forgery / falsification determination of the document in the comparison unit. The method of claim 1, And an image processor for performing one or more of noise reduction of the digital image converted by the A / D converter, detection of contours for character recognition, low / high pass filtering, and region extraction. The method of claim 1, The predetermined information input by the user in the user input unit is information about a high forgery / falsification part of the document. And said predetermined information is inserted into said document as a watermark at the time of issuing said document. The method according to claim 1 or 4, And the inserted watermark is generated by a key generation method, a logo method, or both. The method according to claim 1 or 4, The embedded watermark is a robust watermark, a fragile watermark, or both. The method according to claim 1 or 4, The embedded watermark is an off-line detector, characterized in that the optical watermark using a light interference phenomenon or a surface latent phenomenon.