TWI398829B - Floating watermark embedding device and verification device, digital floating watermark verification system - Google Patents

Description

Watermark embedding device and verification device, digital watermark verification system

The invention relates to an embedding device and a verification device, a verification system, in particular to a watermark embedding device and a verification device applied to an anti-counterfeiting certificate, and a digital watermark verification system.

Today's society is full of all kinds of forged certificates, especially forgery technology. Therefore, when receiving a paper certificate, it is difficult to judge the authenticity of the certificate. There is a need for a technology that can verify the authenticity of a paper certificate in real time.

Accordingly, it is an object of the present invention to provide a watermark embedding apparatus that avoids the above-described deficiencies.

The watermark embedding device comprises: an image conversion module, receiving an original certificate image generated according to a certificate number, and performing color separation on the original certificate image to obtain a captured pixel component and a residual pixel component, thereby further Converting the captured pixel component into a frequency domain data having a plurality of Fourier coefficients; a memory body electrically connected to the image conversion module to temporarily store the residual pixel component; a random number seed generator, according to the certificate number and a cryptographic key is logically operated to obtain a random number seed; a core module is electrically connected to the image conversion module to receive the frequency domain data having a plurality of Fourier coefficients, and according to the random number seed from the frequency domain A part of the Fourier coefficients are selected as a plurality of embedding points, and the Fourier coefficient values of the embedding points are respectively increased to obtain a watermark embedded frequency domain data; and an image recovery module is electrically connected to the core mode. And the memory to receive the embedded watermark frequency domain data and the residual pixel component, and perform image processing to obtain A certificate embedded watermark image.

Accordingly, a second object of the present invention is to provide a watermark verification apparatus.

The watermark verification device is configured to verify a certificate image to be verified with a unique certificate number, comprising: an image conversion module, performing color separation on the received image to obtain a captured pixel component, and then Converting the pixel component into a frequency domain data having a plurality of Fourier coefficients; a random seed generator, performing logical operations on the certificate number and a cryptographic key to obtain a random seed; and a verification module, electrically connecting The image conversion module and the random number seed generator to receive the frequency domain data having the plurality of Fourier coefficients and the random number seed, and find coordinates of the data having the larger Fourier coefficient value from the frequency domain data. Performing a coordinate position of the detected watermark, and selecting a part of the Fourier coefficients from the frequency domain data as a plurality of embedded points according to the random seed, to calculate the coordinates of the plurality of embedded points as a group The coordinate position of the watermark, and then according to the relationship between the coordinate position of the detected watermark of the group and the coordinate position of the calculated watermark of the group, Certificate off of the image to be verified is true or dummy.

Accordingly, a third object of the present invention is to provide a digital watermark verification system.

The digital watermark verification system comprises: a watermark embedding device, comprising: an image conversion module, receiving an original certificate image generated according to a certificate number, and color-separating the original certificate image to obtain a captured pixel a component and a residual pixel component, thereby converting the captured pixel component into a frequency domain data having a plurality of Fourier coefficients; a memory body electrically connected to the image conversion module to temporarily store the residual pixel component; a generator, performing a logical operation according to the certificate number and a cryptographic key to obtain a random seed; a core module electrically connected to the image conversion module to receive the frequency domain data having a plurality of Fourier coefficients, and according to The random seed selects a part of the Fourier coefficients from the frequency domain data as a plurality of embedded points, and increases the Fourier coefficient values of the embedded points respectively to obtain a watermark embedded frequency domain data; and an image reply a module electrically connected to the core module and the memory to receive the watermark embedded frequency domain data and the residual a component of the image, and performing image processing to obtain a certificate image embedded in the watermark; and a watermark verification device for verifying a certificate image to be verified having a unique certificate number, including: an image conversion module, Receiving an image for color separation to obtain a captured pixel component, thereby converting the captured pixel component into a frequency domain data having a plurality of Fourier coefficients; a random seed generator, according to the certificate number and the cryptographic key Performing a logical operation to obtain a random number seed; and a verification module electrically connected to the image conversion module and the random number seed generator to receive the frequency domain data having the plurality of Fourier coefficients and the random number seed, and The coordinates of the data with the larger Fourier coefficient value are found from the frequency domain data as the coordinate position of the detected watermark, and a part of the Fourier coefficients are selected from the frequency domain data as the majority according to the random number seed. Embedding points to treat the coordinates of the plurality of embedded points as coordinate positions of a set of calculated watermarks, and then according to the group The relationship between the watermark and the coordinate position of the coordinate position computed watermark, the image of the determined certificate to be verified is true or dummy.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

As shown in FIG. 1, a preferred embodiment of the digital watermark verification system of the present invention comprises: a pattern designer 1, a watermark embedding device 2, a digital printer 3, a scanner 4, and a watermark verification device 5. .

A management center can utilize the digital watermark verification system of the present invention to accept commissioned printing of a paper certificate with anti-counterfeiting function. In the future, we can assist in the verification of the authenticity of these certificates. For example, a diploma can be printed by a school, and when a graduate takes a diploma to a company for a job, the company can help verify the authenticity of the diploma through the management center to prevent counterfeiting. In addition, in addition to the graduation certificate, the certificate in this embodiment may further include: a certificate, a professional certificate, a notarial certificate, a commission, a check, a right, and the like.

Specifically, the management center uses the pattern designer 1 to plan the content of a certificate, and uses the watermark embedding device 2 to embed the watermark with the anti-counterfeiting function in the certificate, and then uses the digital printer 3 to use the certificate. Printed on paper. In the future, when the enterprise wants the management center to assist the verification certificate, the certificate image scanned by the enterprise using the scanner 4 can be received by the network, and the authenticity of the certificate can be verified by the watermark verification device 5, and the verification is realized. effect. The following is a detailed introduction to each process.

<Making a paper certificate with a watermark>

The pattern designer 1 prepares a single certificate number for each certificate, and arranges according to the certificate number and a certificate related information to generate a digital original certificate image so that the information is displayed in the original certificate image. The relevant information of the certificate includes the name of the certificate, the date of issuance, the name of the certificate holder, the date of birth, and so on.

Referring to FIG. 2, the watermark embedding device 2 is connected to the pattern designer 1 to receive the original certificate image, and embeds a digital watermark on the original certificate image according to the certificate number and a cryptographic key to obtain an embedded watermark. The certificate image includes: an image conversion module 21, a memory 22, a random seed generator 23, a core module 24, and an image recovery module 25.

The image conversion module 21 is connected to the pattern designer 1 to receive the original certificate image, and color-separates the original certificate image to obtain a captured pixel component and a residual pixel component, thereby converting the captured pixel component into a A frequency domain data having a plurality of Fourier coefficients, and having a color component extractor 211 and a Fourier converter 212.

The color component extractor 211 is received by the pattern designer 2 to receive the original certificate image, and color-separates the original certificate image to obtain a captured pixel component and a residual pixel component.

The color in the image includes a red pixel component, a blue pixel component, and a green pixel component, and the modified red or blue pixel component has less impact on the color image, and the modified green pixel component is for the image. The quality of the captured pixel component is the red pixel component in the present embodiment and the residual pixel component is the “green pixel component + blue pixel component”, but is not limited thereto, and the captured pixel component may also be Is the blue pixel component.

The memory 22 is electrically coupled to the color component extractor 211 to temporarily store the residual pixel component.

A Fourier converter 212 is electrically coupled to the color component extractor 211 to receive the captured pixel component and perform Fourier transform on the captured pixel component to obtain the frequency domain data having a plurality of Fourier coefficients.

The random seed generator 23 performs a logical operation based on the certificate number and a cryptographic key to obtain a random seed. In the embodiment, the logical operation is a "Exclusive OR" operation, but Not limited to this, it can be other ways.

The core module 24 is electrically connected to the image conversion module 21 to receive the frequency domain data having a plurality of Fourier coefficients, and selects a part of Fourier coefficients from the frequency domain data as an embedding point according to the random number seed, and The Fourier coefficients of the embedded points are respectively increased to obtain a watermark embedded frequency domain data, and have an embedded point divider 241, a processor 242, and a coefficient generator 243.

The embedded point divider 241 is electrically connected to the Fourier converter 212 to receive the frequency domain data, and is divided according to a preset parameter in a preset divided region of the frequency domain data to obtain n candidates having a Fourier coefficient value. Embed the point. The preset parameter has a preset maximum radius R _MAX , a preset minimum radius R _min , a division unit R, and a division angle θ, as shown in FIG. 3 .

The processor 242 is electrically connected to the embedded point divider 241 and the Fourier converter 212, and optionally selects m embedded points from the n candidate embedded points, thereby obtaining Group embedding points. And preferably, m=n/2, so that The value is the largest, and the chance of being cracked is reduced, for example, taking n = 56, m = 28 as an example. About 700 megabytes.

Further, the processor 242 is further connected to the random number seed generator 23 to receive the random number seed, and according to the random number seed A set of embedding points is selected from the group embedding points, and the coordinate position of the group embedding points is regarded as the coordinate position of the watermark.

In this example, the processor can execute a random number function (such as randperm(n) provided by Matlab software), and the random number function can randomly arrange the n candidate embedding points, and then take the first m. The purpose of optionally selecting m embedding points among the n candidate embedding points can be achieved, and the random number function further generates an exclusive ordering according to a preset initial value, so that only a random number of random seeds is needed. As the preset initial value, the same sorting can be generated each time the random number function is executed.

The coefficient generator 243 is electrically connected to the processor 242 and the Fourier converter 212 to receive the frequency domain data, and adds a predetermined constant to the Fourier coefficient at the coordinate position of the obtained watermark to obtain a The frequency domain data embedded in the watermark.

Here, by the formula, the coefficient generator 243 can execute the formula M'(u,v)=M(u,v)+c, M'(-u,-v)=M(-u,-v)+c In order to modify the Fourier coefficient to a relatively large value, wherein the parameters (u, v), (-u, -v) respectively represent the coordinate position of the watermark and the coordinate position of the symmetric origin, then M(u, v) represents The absolute value of the watermark's Fourier coefficients is performed, and c is a preset constant.

The image recovery module 25 is electrically connected to the core module 24 and the memory 22 to receive the watermark embedded frequency domain data and the residual pixel component, and performs image processing to obtain a watermark embedded certificate image, and has An inverse Fourier transformer 251 and a color component combiner 252.

The inverse Fourier transformer 251 is electrically connected to the coefficient generator 243 to receive the watermark embedded frequency domain data, and inversely Fourier transforms the watermark embedded frequency domain data into a watermarked captured pixel component.

The color component combiner 252 is electrically coupled to the inverse Fourier transformer 251 and the memory 22, and combines the watermarked captured pixel component and the residual pixel component into a watermarked certificate image.

The digital printer 3 is electrically coupled to the color component combiner 252 to receive the watermarked certificate image and print it out to obtain a paper certificate having a watermark.

<Verify the authenticity of the paper certificate>

The scanner 4 scans a paper certificate to be verified into a certificate image to be verified.

Referring to FIG. 4, the watermark verification device 5 is adapted to verify a certificate image to be verified with a unique certificate number, including: a rotation zoom module 51, an image conversion module 52, a random seed generator 53, and a The verification module 54 and a display 55 are provided.

The rotation zoom module 51 is electrically connected to the scanner 4 to receive the certificate image to be verified, first determining whether the certificate image to be verified is rotated, and if so, correcting the image and determining whether it is scaled, if Then, the zoom is further performed to output a size-scaled image, and has a Hall's converter 511, a determiner 512, and an image scaler 513.

A Hough converter 511 is electrically connected to the scanner 4 to receive the certificate image to be verified to detect an edge line of the certificate image to be verified and to obtain a slope of each edge line.

The determiner 512 is electrically connected to the Hough converter 511 and the scanner 4 to learn the slope and receive the certificate image to be verified, and output a signal according to the slope to determine whether the certificate image to be verified is rotated. Correcting the image, wherein, if it is rotated, the determiner 512 reversely rotates the certificate image to be verified to obtain the corrected image, and if not, the determiner still outputs the certificate image to be verified as the corrected image. .

The image scaler 513 is electrically connected to the determiner 512 to receive the corrected image, and determines whether the corrected image is scaled according to a preset image size. If yes, the corrected image is scaled to obtain a size-scaled image, and if not, The corrected image is directly output to scale the image as the size.

The image conversion module 52 is electrically connected to the rotation scaling module 51 to receive the size-scaled image, and converts the size-scaled image into a frequency domain data having a plurality of Fourier coefficients, and has a color component extractor and a Fourier transform. Device.

The color component extractor 521 is electrically connected to the image scaler to receive the size-scaled image, and performs color separation on the size-scaled image to obtain a captured pixel component and a residual pixel component, wherein the captured pixel component and This residual pixel component is as described above.

A Fourier converter 522 is electrically coupled to the color component extractor 521 to receive the captured pixel component and Fourier transform the captured pixel component to obtain a frequency domain data having a plurality of Fourier coefficients.

The random seed generator 53 performs a "mutual exclusion" operation based on the certificate number and a cryptographic key to obtain a random seed.

The verification module 54 is electrically connected to the image conversion module 52 and the random number seed generator 53 to receive the frequency domain data having a plurality of Fourier coefficients, and to find the data having the larger Fourier coefficient value from the frequency domain data. The coordinate is used as a coordinate position of the detected watermark, and a part of the Fourier coefficient is selected from the frequency domain data as a plurality of embedded points according to the random seed, so that the coordinates of the plurality of embedded points are regarded as one Calculating the coordinate position of the watermark calculated by the group, and determining, according to the relationship between the coordinate position of the detected watermark and the coordinate position of the calculated watermark of the group, the certificate image to be verified is true or false, and has An embedded point divider 541 and a verifier 542.

The embedded point divider 541 is electrically connected to the Fourier converter 522 to receive the frequency domain data, and is divided according to a preset parameter in a preset divided region of the frequency domain data to obtain n candidates having a Fourier coefficient value. Embed the point.

The preset divided area and the preset parameter are the same as the watermark embedding device 2.

The verifier 542 is electrically connected to the embedded point divider 541 and the Fourier converter 522, and the Fourier coefficients of the n candidate embedding points are arranged in size, and the coordinate position of the first half of the Fourier coefficients is obtained to obtain the group. The coordinate position of the detected watermark.

The verifier 542 is further connected to the random seed generator 53 to receive the random seed. First, m=n/2 embedding points are selected from the n candidate embedding points to obtain Group embedding points, then according to the chaotic seed from the The group embedding point selects a set of embedding points, and the coordinate position of the group embedding point is taken as the coordinate position of the watermark calculated by the group.

The verifier 542 further compares the coordinate position of the detected watermark with the coordinate position of the calculated watermark to obtain a correlation result, and determines whether the correlation result exceeds a set threshold, and if so, outputs a The verification result indicates that the paper certificate to be verified is true, and vice versa, the verification result indicates that it is false.

The display 55 is electrically connected to the verification module 54 to display whether the paper certificate to be verified is true or false.

In summary, the present invention has the following advantages:

(1) The watermark verification device 5 uses the Hough converter 511 to detect a straight line of an image edge, so that the image rotation angle can be stably detected when the image is subjected to an attack of a zoom or a resolution change.

(2) The verifier 542 arranges the Fourier coefficients of the n embedded points by size, and takes the larger one of the first half of the Fourier coefficients as the peak coefficient, and can verify the authenticity at one time without modifying the adjustment threshold as in the conventional technique. The value is obtained to obtain a sufficient number of peak coefficients, so the verification speed is fast and the efficiency is improved.

(3) The operation of the watermark verification device 5 is completely automated, without human intervention, saving time and verifying the authenticity of the paper certificate correctly and quickly. It is the only effective technology that can eliminate the forgery of the certificate.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

1. . . Pattern designer

2. . . Watermark embedding device

twenty one. . . Image conversion module

211. . . Color component extractor

212. . . Fourier converter

twenty two. . . Memory

twenty three. . . Random seed generator

twenty four. . . Core module

241. . . Embedded point divider

242. . . processor

243. . . Coefficient generator

25. . . Image recovery module

251. . . Inverse Fourier Transformer

252. . . Color component combiner

3. . . Digital printing machine

4. . . scanner

5. . . Watermark verification device

51. . . Inverse Fourier Transformer

511. . . Holmes converter

512. . . Judger

513. . . Image scaler

52. . . Image conversion module

521. . . Color component extractor

522. . . Fourier converter

53. . . Random seed generator

54. . . Inverse Fourier Transformer

541. . . Embedded point divider

542. . . Validator

55. . . monitor

Figure 1 is a view of a preferred embodiment of the present invention;

Figure 2 is a diagram of a watermark embedding device;

Figure 3 is a diagram of a divided area; and

4 is a diagram of a watermark verification device.

1. . . Pattern designer

2. . . Watermark embedding device

3. . . Digital printing machine

4. . . scanner

5. . . Watermark verification device

Claims (13)

A watermark embedding device comprises: an image conversion module, receiving an original certificate image generated according to a certificate number, and performing color separation on the original certificate image to obtain a captured pixel component and a residual pixel component, thereby further Converting the captured pixel component into a frequency domain data having a plurality of Fourier coefficients; a memory body electrically connected to the image conversion module to temporarily store the residual pixel component; a random number seed generator, according to the certificate number and a cryptographic key is logically operated to obtain a random number seed; a core module is electrically connected to the image conversion module to receive the frequency domain data having a plurality of Fourier coefficients, and according to the random number seed from the frequency domain A part of the Fourier coefficients are selected as a plurality of embedding points, and the Fourier coefficient values of the embedding points are respectively increased to obtain a watermark embedded frequency domain data; and an image recovery module is electrically connected to the core mode. And the memory to receive the frequency domain data of the embedded watermark and the residual pixel component, and perform image processing to A certificate to the embedded watermark image. The watermark embedding device of claim 1, wherein the image conversion module comprises: a color component extractor, receiving the original certificate image, and performing color separation on the original certificate image to obtain the image Taking a pixel component and the residual pixel component; and a Fourier converter electrically connected to the color component extractor to receive the captured pixel component, and performing Fourier transform on the captured pixel component to obtain the majority of Fourier coefficients Frequency domain data. The watermark embedding device of claim 1, wherein the core module comprises: an embedded point divider, electrically connected to the image conversion module to receive the frequency domain data, and the data in the frequency domain a predetermined divided area is divided according to a preset parameter to obtain a plurality of candidate embedded points having a Fourier coefficient value; a processor electrically connected to the embedded point divider and the image conversion module, and from all The candidate embedding point finds half of the candidate embedding points that are not repeated, and performs an unordered permutation combination to obtain an embedding point of multiple arrays, and the processor is further connected to the random seed generator to receive the random seed. And selecting a set of embedding points from the multi-array embedding points according to the random seed, and treating the coordinate position of the set embedding point as a coordinate position of a watermark; and a coefficient generator connected to the processor and the The image conversion module receives the frequency domain data, and adds a preset constant to the Fourier coefficient at the coordinate position of the watermark to obtain a frequency domain embedded in the watermark data. The watermark verification device according to claim 3, wherein the preset parameter has a preset maximum radius, a predetermined minimum radius, a division unit, and a division angle. The watermark embedding device of claim 1, wherein the image recovery module comprises: an inverse Fourier converter electrically connected to the core module to receive the watermark embedded frequency domain data, and The watermark embedded frequency domain data is inverse Fourier transformed into a watermarked pixel component embedded in the watermark; and a color component combiner is electrically connected to the inverse Fourier transformer and the memory, and the watermark is embedded in the watermark The pixel component and the residual pixel component are combined into the embedded watermarked certificate image. The watermark embedding device of claim 1, wherein the logical operation is a "mutual exclusion" operation. A watermark verification device is configured to verify a certificate image to be verified with a unique certificate number, comprising: an image conversion module, performing color separation on an accepted image to obtain a captured pixel component, and then Converting the pixel component into a frequency domain data having a plurality of Fourier coefficients; a random seed generator, performing logical operations on the certificate number and a cryptographic key to obtain a random seed; and a verification module, electrically connecting The image conversion module and the random number seed generator to receive the frequency domain data having the plurality of Fourier coefficients and the random number seed, and find coordinates of the data having the larger Fourier coefficient value from the frequency domain data. Performing a coordinate position of the detected watermark, and selecting a part of the Fourier coefficients from the frequency domain data as a plurality of embedded points according to the random seed, to calculate the coordinates of the plurality of embedded points as a group The coordinate position of the watermark, and then the relationship between the coordinate position of the detected watermark and the coordinate position of the calculated watermark of the group Analyzing the image of the certificate to be verified is true or dummy. The watermarking verification device according to claim 7, further comprising: a rotation zoom module electrically connected to the image conversion module, and determining whether the certificate image to be verified is rotated, and is rotated The certificate image is corrected, and it is further judged whether it is scaled, and if so, it is further scaled to output a size-scaled image to the image conversion module. The watermarking verification device according to claim 8, wherein the rotary zoom module comprises: a Holker converter for detecting an edge line of the certificate image to be verified and knowing each edge line a slope; a determiner, receiving the certificate image to be verified and electrically connected to the Hough converter to know the slope, and outputting a corrected image according to the slope to determine whether the certificate image to be verified is rotated If the device is rotated, the determiner reversely rotates the certificate image to be verified to obtain the corrected image. If not, the determiner still outputs the certificate image to be verified as the corrected image; An image scaler is electrically connected to the determiner to receive the corrected image, and determines whether the corrected image is scaled according to a preset image size. If yes, the corrected image is scaled to obtain a size-scaled image, and if not, The corrected image is directly output to scale the image as the size. The watermarking verification device according to the seventh aspect of the invention, wherein the image conversion module comprises: a color component extractor electrically connected to the image scaler to receive the size scaled image and scale the size Performing color separation on the image to obtain the captured pixel component and a residual pixel component; and a Fourier converter electrically connected to the color component extractor to receive the captured pixel component and performing Fourier transform on the captured pixel component The frequency domain data having a plurality of Fourier coefficients is obtained. The watermarking verification device according to the seventh aspect of the invention, wherein the verification module comprises: an embedded point divider, electrically connected to the image conversion module to receive the frequency domain data, and the data in the frequency domain a predetermined divided area is cut according to a preset parameter to obtain coordinates of a plurality of candidate embedded points; and a validator is connected to the embedded point divider and the image conversion module, and the plurality of candidate insertion points are The Fourier coefficients are arranged in a size, and the coordinate position of the first half of the Fourier coefficient is obtained to obtain the coordinate position of the detected watermark of the group; and the verifier is further connected to the random seed generator to receive the chaos a number of seeds, first selecting one of the plurality of candidate embedding points to obtain a multi-array embedding point, and then selecting a set of embedding points from the multi-array embedding point according to the random number seed, and embedding the set of embedding points The coordinate position is taken as the coordinate position of the calculated watermark of the group; and the verifier further sets the coordinate position of the detected watermark of the group and the coordinate position of the calculated watermark of the group The comparison is performed to obtain a correlation result, and it is determined whether the correlation result exceeds a set threshold. If yes, a verification result is output indicating that the paper certificate to be verified is true, and vice versa, the verification result is false. The watermark verification device according to claim 11, wherein the preset parameter has a preset maximum radius, a predetermined minimum radius, a division unit, and a division angle. A digital watermark verification system comprises: a watermark embedding device, comprising: an image conversion module, receiving an original certificate image generated according to a certificate number, and color-separating the original certificate image to obtain a capture a pixel component and a residual pixel component, thereby converting the captured pixel component into a frequency domain data having a plurality of Fourier coefficients; a memory body electrically connected to the image conversion module to temporarily store the residual pixel component; a seed generator, performing logical operations on the certificate number and a cryptographic key to obtain a random seed; a core module electrically connected to the image conversion module to receive the frequency domain data having a plurality of Fourier coefficients, and Selecting a part of the Fourier coefficients from the frequency domain data as a plurality of embedding points according to the random number seed, and increasing the Fourier coefficient values of the embedding points respectively to obtain a watermark embedded frequency domain data; and an image a reply module electrically connected to the core module and the memory to receive the watermark embedded frequency domain data and the And the image processing is performed to obtain a certificate image embedded in the watermark; and a watermark verification device is configured to verify a certificate image to be verified having a unique certificate number, including: an image conversion module, The received image is color separated to obtain a captured pixel component, and the captured pixel component is converted into a frequency domain data having a plurality of Fourier coefficients; a random seed generator, according to the certificate number and the password gold The key is logically operated to obtain a random number seed; and a verification module is electrically connected to the image conversion module and the random number seed generator to receive the frequency domain data having the plurality of Fourier coefficients and the random number seed. And finding the coordinates of the data with the larger Fourier coefficient value from the frequency domain data as the coordinate position of the detected watermark, and selecting a part of the Fourier coefficient from the frequency domain data as the majority according to the random number seed. Embedding points, the coordinates of the plurality of embedding points are treated as coordinate positions of a set of calculated watermarks, and then according to the group The relationship between the detected watermark and the coordinate position of the coordinate position computed watermark, the image of the determined certificate to be verified is true or dummy.