JP2001078013A - Electronic watermark compositing device and image alteration deciding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To composite an electronic watermark with an image photographed by an order receiver based on the request of an orderer by compositing cipher information which is prepared by enciphering image identification information for identifying an input image with the image as an electronic watermark, recording it and reporting a method thereof and the image identification information. SOLUTION: A method for extracting the electronic watermark composited with an image 10, a method for deciphering the cipher information to be used as electronic watermark and the image identification information of the image 10 to be used for preparing the cipher information are reported by the manager of a laboratory system to the user of an image alteration discriminating device 90, namely, to the orderer. The order receiver receives a recording medium such as CD-ROM storing a composited image 11 from a laboratory system, selects a required image out of recorded images and presents it to the orderer as photograph data for proving progress. In order to discriminate whether an image 12 presented by the order receiver is altered, the orderer uses the image alteration discriminating device 90.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image synthesizing apparatus for synthesizing an electronic watermark with an image and an image falsification judging apparatus for judging whether the image has been falsified.

[0002]

2. Description of the Related Art At a construction site, a construction contractor takes a picture of the construction site at each stage of construction in order to explain the amount of work completed and submits the photograph to the ordering party of the construction. Report that

When a construction photograph is taken with an APS camera or a digital camera, the digital image data is stored in a CD-RO.
The submission is made in electronic media such as M. However, since the digital image data can be easily changed by software such as a computer, there is a possibility that a contractor of the construction may falsify the data. for that reason,
There is a need for a method for the orderer of the construction to determine that the image data submitted by the contractor of the construction has not been tampered with.

As an invention for determining whether image data has been tampered with, Japanese Patent Application Laid-Open No. H11-98344 (published on 199
(April 9, 2009) stores the original image and a watermark image embedded in the original image in advance, and detects a difference between the composite image and the original image when a composite image that may have been tampered is input. Discloses a falsification determination method and apparatus for extracting a watermark image embedded in a composite image, comparing the extracted watermark image with a previously registered watermark image, and determining whether or not falsification has occurred.

[0005]

However, in the above-mentioned invention, since the falsification determination device needs to store the original image in advance, it is necessary to determine the falsification of many images such as construction photographs. In this case, there is a problem that the storage capacity for storing the original image becomes large.

In order to solve the above-mentioned problems, the present invention provides an image synthesizing apparatus for synthesizing an electronic watermark with an image photographed by a contractor based on a request from the contractor, and an image which the contractor submits to the orderer. It is an object of the present invention to provide an image tampering determination device that determines whether or not there is tampering. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous embodiments of the present invention.

[0007]

According to a first aspect of the present invention, there is provided a digital watermark synthesizing apparatus for synthesizing an electronic watermark with an image, comprising: an image input unit for inputting the image; A cryptographic unit for generating cryptographic information obtained by encrypting image identification information for identifying an image, a digital watermark synthesizing unit for synthesizing the cryptographic information as an electronic watermark with an image, and recording the image synthesized by the digital watermark synthesizing unit. An image recording unit, a method for extracting a digital watermark, a method for decrypting encrypted information,
And an image information notifying section for notifying image identification information.

[0008] The encryption creating section may create the encryption information by creating a digital signature of the image identification information based on the secret key in the public key encryption system.

The image identification information may be different for each requester of the image recording. The image identification information may be different identification information for each image recording order. The image identification information may be different identification information for each image.

According to a second aspect of the present invention, there is provided an image falsification determining apparatus for determining whether or not an image has been tampered with, comprising: an image input unit for inputting an image; a digital watermark extracting method for the image; An encryption / decryption method for decoding, an image information input unit for inputting image identification information for identifying the image, a digital watermark extraction unit for extracting a digital watermark of the image based on the digital watermark extraction method, and a cipher / decryption method. An encryption / decryption unit that decodes an electronic watermark, and a decryption determination unit that determines whether or not the image has been tampered with by comparing the decrypted data decrypted by the encryption / decryption unit with the image identification information. I do.

The encryption / decryption unit may obtain decrypted data by regarding the digital watermark as a digital signature and decrypting the digital signature based on a public key in a public key cryptosystem.

[0012] The image identification information may be identification information different for each photographer of the image or identification information different for each image.

According to a third aspect of the present invention, there is provided an image falsification judging method for judging whether or not an image has been falsified. The method includes the steps of inputting an image, extracting a digital watermark of the image, and decrypting a digital watermark code. , Input identification information for identifying the image, extract the digital watermark of the image based on the digital watermark extracting method, decode the digital watermark based on the decoding method, extract the decoded data, It is characterized in that the presence or absence of falsification of the image is determined by comparing with the identification information.

[0014] The identification information of the image may be identification information different for each photographer of the image or identification information different for each image.

A recording medium storing a computer program for determining whether an image has been tampered with, the program comprising: an image input module for inputting an image to a computer; A decryption method for decrypting an encryption of an image, an image information input module for inputting image identification information for identifying an image, a digital watermark extraction module for extracting a digital watermark of an image based on the digital watermark extraction method, and a decryption method. A decryption module that decrypts the digital watermark, and a falsification determination module that determines whether the image has been tampered with by comparing the decrypted data decrypted by the decryption module with the image identification information. And

The above summary of the present invention does not list all of the necessary features of the present invention, and a sub-combination of these features can also be an invention.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described through embodiments of the present invention. However, the following embodiments do not limit the invention according to the claims and are described in the embodiments. Not all combinations of the features described above are essential to the solution of the invention.

Hereinafter, the present invention will be described by using an example of a construction photograph. However, the present invention is not limited to a construction photograph, and is generally used for synthesizing a digital watermark with digital image data and judging whether there is tampering. can do.

FIG. 1 shows a digital watermark synthesizing apparatus 80 according to the present invention.
1 is a configuration diagram of a system capable of determining whether a digital image of a construction photograph delivered by a construction contractor has been falsified by using the image falsification determination device 90.

The digital watermark synthesizing device 80 reads image data from a silver halide film, an APS (Advanced Photo System) film, a semiconductor memory in which an image of a digital camera is recorded, and converts the digitized image to a medium such as a CD-ROM. Record. Normally, the digital watermark synthesizing device 80
Is used by lab system employees in a lab system that provides photo development services.

The contractors for the construction work are silver halide film, APS
(Advanced Photo System) An original photo image I0 recorded on a film, a semiconductor memory, or the like is provided to a laboratory system. An employee of the lab system inputs the original image I0 into the digital watermark synthesizing device 80.

The digital watermark synthesizing device 80 digitizes the photograph I0, creates encryption information based on the image identification information for identifying the photograph I0, and combines the created encryption information with the image I0 as an electronic watermark. Digital watermark synthesizing device 80
Records the synthesized image I1 on a CD-ROM or the like and provides it to the contractor.

Since the composite image I1 cannot be distinguished from the original image I0 with the naked eye, it is difficult for the contractor to detect a digital watermark from the composite image I1.

In the digital watermark synthesizing device 80, the image I
The method of extracting the digital watermark combined with the digital watermark, the method of decrypting the encrypted information used as the digital watermark, and the image identification information of the image I0 used to create the encrypted information are transmitted to the image falsification determination device by the lab system administrator. 90 users, that is, the orderer of the construction are notified. As the notification means, mail, electronic mail, or the like can be used.

The contractor receives a composite image I1 from the lab system.
Receiving a recording medium such as a CD-ROM in which
A required image is selected from images recorded in a D-ROM or the like and submitted to the orderer as photographic data for proving the progress of the construction. It is assumed that the image submitted to the orderer is an image I2 corresponding to the composite image I1, and that the orderer may have altered the image I1 and created the image I2.

The orderer uses the image tampering determination device 90 to determine whether the image I2 submitted by the orderer has been tampered with. The electronic watermark extraction method, encryption / decryption method, and image identification information of the image I1 are input to the image tampering determination device 90 in advance. The image tampering determination device 90 receives the image I2 and extracts the digital watermark of the image I2 by the digital watermark extracting method of the image I1. The extracted digital watermark is regarded as encryption information and decrypted by the encryption / decryption method of the image I1. Further, the decoded data is compared with the image identification information of the image I1.
It is determined that the image I2 has not been tampered with, and if they do not match, it is determined that the image I2 has been tampered with from the image I1.

FIG. 2 is a block diagram of the digital watermark synthesizing device 80 according to the first embodiment of the present invention. The digital watermark synthesizing device 80 includes an image input unit 10, a processing unit 20, a recording unit 40, and an output unit 50.

The image input unit 10 inputs an image. When an image captured by a silver halide camera is input to an image processing apparatus, the image input unit 10 includes a film scanner that optically scans an image on a photographic film such as a negative film or a positive film and converts the image into an electric signal. Is used. When a digital image captured by a digital camera is input to an image processing apparatus, the image input unit 10 uses various reading devices corresponding to a recording medium storing the input digital image.
For example, a reading device for reading image data from a removable recording medium such as a nonvolatile semiconductor memory card is used for the image input unit 10. When reading image data from a floppy disk, MO, CD-ROM, or the like, a floppy drive, MO drive, CD drive, or the like is used as the image input unit 10, respectively.

The processing section 20 creates encryption information and combines the encryption information with the image input by the image input section 10 as a digital watermark. The detailed configuration and operation of the processing unit 20 will be described later.

The recording section 40 records the image received from the processing section 20 on a removable recording medium. As a recording medium, an optical recording medium such as a writable CD or DVD, an M
A magneto-optical recording medium such as O, a magnetic recording medium such as a floppy (registered trademark) disk, and the like are conceivable. As the recording unit 40, a CD-R drive, DVD drive, MO drive, floppy drive, or the like is used. Note that the recording unit 40 may record the image in a storage device such as a semiconductor memory.

The output unit 50 outputs the image received from the processing unit 20. For example, when displaying an image on a screen, a monitor that displays the image is used as the output unit 50.

Next, the encryption information created by the processing unit 20 will be described. For the creation of the encryption information, for example, a digital signature using a public key cryptosystem can be used.

In the public key cryptosystem, the encryption key and the decryption key are different, and the encryption key is made public and the decryption key is kept secret. The public encryption key is called a public key, and the secret decryption key is called a secret key. On the other hand, the digital signature is a function for authenticating that the message is not falsified and that the sender of the message is not a fake. Hereinafter, a method for implementing a digital signature using a public key cryptosystem will be described.

For the message M, the data encrypted by the encryption function E using the public key pk is expressed as E (M, pk)
And Further, for the message M, the data decrypted by the decryption function D using the secret key sk is represented by D (M, sk).
And

In the public key cryptosystem, when a public key pk and an encryption function E are given, encrypted data E (M, p
It is easy to find k). When the secret key sk and the decryption function D are given, the decrypted data D (M, s
It is easy to find k).

Since everyone knows the public key pk and the encryption function E, the encrypted data E
Although (M, pk) can be easily calculated, the message M cannot be restored from the encrypted data E (M, pk) without knowing the secret key sk. That is, it is difficult to obtain the decryption function D which is the inverse function of the encryption function E in terms of the amount of calculation.

If the secret key sk and the decryption function D are known, the secret key sk is used for the encrypted data E (M, pk).
And D (E (M, pk),
By determining the value of sk), the message M can be easily restored. That is, the equation M = D (E (M, pk), sk) holds.

In order to realize a digital signature using the public key cryptosystem, the operations of encryption and decryption of the public key cryptosystem are used in reverse. In the public key cryptosystem, by using encryption and decryption in reverse, a communication message can be encrypted by a decryption function, and the communication message encrypted by the encryption function can be decrypted.

It is assumed that the sender of the message M knows the secret key sk and the decryption function D. The sender encrypts the message M using the secret key sk and the decryption function D. The encrypted message is D (M, sk). This is called a digital signature of the message M. The sender of the communication message M transmits the digital signature D (M, sk) of the communication message M together with the communication message M to the recipient of the communication.

The receiver decrypts the encrypted data D (M, sk) with the encryption function E using the public key pk.
The decrypted data is E (D (M, sk), pk). During the communication, the message M and the digital signature D (M, s
Unless k) has been tampered with, the decrypted data E
The value of (D (M, sk), pk) matches M. That is, the equation M = E (D (M, sk), pk) holds.

Assuming that the message M has been altered to M *, the data E (D (M, s
k) and pk) become M, but the received message is M *. That is, the equation M * ≠ M = E (D (M, sk *), pk) holds. Accordingly, since the decrypted result of the digital signature is different from the received message, it is possible to know that the message has been falsified.

Here, only the sender of the message can know D (M, sk) knowing the secret key sk. Therefore, after the third party alters the message M to M *, the digital signature D (M
*, Sk) cannot be created. That is,
It is not possible to conceal the falsification by falsifying the message M and falsifying the digital signature accordingly.

Another person communicating with the same public key cryptosystem as the communication recipient impersonates the sender of the message M.
Digital signatures cannot be created. This is because only the sender of the communication unit M knows the secret key sk, so that another person cannot create the digital signature D (M, sk) of the message M. Suppose another person has a different secret key sk
When the digital signature D (M, sk *) of the message M, which is obtained by using * and the decryption function D, is sent to the communication partner together with the message M, the receiver of the communication receives the digital signature D (M, sk *).
*). The restored message is E (D (M, sk
*), Pk), which does not match the message M. That is, the equation M ≠ E (D (M, sk *), pk) holds. Therefore, it is possible to detect that another person has transmitted the message M by impersonating the sender of the message M.

As described above, a digital signature can be realized by using the public key cryptosystem. That is, it is possible to authenticate that the message has not been falsified and that no one has transmitted the message by impersonating the true sender of the message. Public key cryptography and digital signatures are described in detail in "Introduction to Cryptographic Theory" (Eiji Okamoto, Kyoritsu Shuppan).

In the digital watermark synthesizing device 80 of the present embodiment, the image identification information ID is used
A digital signature of the image identification information ID is created and combined with the image as a digital watermark.

The image identification information ID is, for example, contractor identification information for identifying a contractor, order identification information for identifying an order when the contractor requests the lab system to digitize an image, and the image input unit 10 inputs. Any of the identification information for each image for identifying the image may be used.

FIG. 3 is a functional block diagram of the processing section 20 of the digital watermark synthesizing apparatus 80 of the present embodiment. Processing unit 20
Has an encryption creating unit 22, a digital watermark synthesizing unit 24, and an image information notifying unit 26.

The encryption creating unit 22 creates a digital signature as an example of encryption information using the secret key of the public key encryption system and the image identification information ID. The digital watermark synthesizing device 80
Public key cryptography is used between the administrator of the lab system that uses the method and the orderer of the construction, the secret key is kept secret by the administrator of the lab system, and the public key is notified to the orderer.

The digital watermark synthesizing section 24 is composed of
Is combined with the image input by the image input unit 10 as a digital watermark.

When the image identification information ID is the contractor identification information, if the same contractor is used, the same digital signature is created on all the images input by the image input unit 10 and embedded as a digital watermark.

When the image identification information ID is order identification information, a different digital signature is created for each order unit and embedded as a digital watermark, even for the same order receiver.

When the image identification information ID is identification information different for each image, a different digital signature is created for each image input by the image input unit 10 and embedded as a digital watermark.

As an example of the image identification information ID that differs for each image, for example, a file name of an image generated at random may be used. Alternatively, a part of the image data may be extracted and used as the image identification information ID. Further, information that differs for each image, such as color information of image data, information on brightness, and saturation, may be used as the image identification information ID.

The image information notifying unit 26 decodes the digital signature created by the encryption creating unit 22, extracts the digital watermark created by the digital watermark synthesizing unit 24, and executes the process when the encryption creating unit 22 creates the digital signature. Is notified to the orderer of the work or the image falsification determination device 90. E-mail or mail can be used as the notification means.

FIG. 4 is a flowchart of the digital watermark synthesizing method. The digital watermark synthesizing method performed by the digital watermark synthesizing device 80 will be described with reference to FIG.

The image input section 10 inputs an image (S20).
0). The encryption creating unit 22 calculates the
Digital signature D using secret key sk and decryption function D
(ID, sk) is created (S202).

The digital watermark synthesizing section 24 includes
Is combined with the image input by the image input unit 10 as a digital watermark (S204). A method of synthesizing a digital watermark to an image and a method of extracting the synthesized digital watermark from an image are described in “Basic of Digital Watermarking-New Protect Technology for Multimedia” (written by Koko Matsui, Morikita Publishing). Can be used.

The recording section 40 records the image synthesized by the digital watermark synthesizing section 24 on a recording medium such as a CD-ROM (S206).

The image synthesized by using the digital watermark synthesizing device 80 is stored in a CD-ROM or the like by the recording unit 40 and delivered to the order receiving party.

The contractor selects the image stored in the CD-ROM and submits it to the orderer as photographic data describing the construction. The orderer extracts a digital watermark from the image submitted by the orderer, and decrypts the extracted digital watermark according to a digital signature decryption method. When the digital watermark is a digital signature D (ID, sk), the decrypted data is E (D (ID, sk), pk). E (D
It is checked whether (ID, sk), pk) is equal to the image identification information ID previously notified from the lab system, and the presence or absence of tampering is detected.

It is difficult for a contractor to see a digital watermark embedded in an image. If the contractor alters the image data, the information of the digital watermark embedded in the image is destroyed. Therefore, the orderer extracts digital watermark information from the falsified image data, extracts the digital signature,
Even if the digital signature is decrypted, the image identification information ID is not correctly restored. Therefore, the orderer can know that the image data has been falsified by comparing it with the image identification information notified by the administrator of the lab system.

Even if the contractor knows the image identification information ID used to create the digital signature, in the case of the digital signature using the public key cryptosystem, the digital signature cannot be created unless the private key is known. . Therefore, the contractor cannot himself create a digital signature from the image identification information ID and embed it as a digital watermark in the image.

When contractor identification information is used as the image identification information ID, the digital signature is the same for each contractor. When the order identification information is used as the image identification information ID, the digital signature changes for each order even for the same orderer. Therefore, it becomes difficult for the contractor to find out the digital signature embedded as a digital watermark.

When different identification information is used for each image data as the image identification information ID, the digital signature differs for each image, so that the contractor cannot see the digital signature embedded in the image as a digital watermark. Becomes more difficult, and the effect of preventing tampering can be enhanced.

FIG. 5 is a configuration diagram of an image falsification determination device 90 according to the second embodiment of the present invention. The image falsification determination device 90 includes an image input unit 11 and an image information input unit 12
, A processing unit 60, and an output unit 50.

The image input section 11 inputs an image stored in a recording medium. Floppy disk, MO, CD-R
When reading image data from an OM or the like, the image input unit 1
Floppy drive, MO drive,
A CD drive or the like is used.

The image information input unit 12 includes a method of extracting a digital watermark for an image input by the image input unit 11, a method of decrypting a digital signature as an example of a method of decrypting encryption code information, and a method of decrypting image identification information. Enter your ID.

The processing section 60 extracts the digital watermark of the image input by the image input section 10, uses the extracted digital watermark as a digital signature, decodes the digital signature, extracts the image identification information, and determines whether or not there has been tampering. I do.

The output section 50 outputs the image received from the processing section 20. For example, when displaying an image on a screen, a monitor that displays the image is used as the output unit 50.

FIG. 6 is a functional block diagram of the processing section 60. The processing unit 60 includes a digital watermark extraction unit 62, an encryption / decryption unit 64, and a falsification determination unit 66.

The digital watermark extracting unit 62 extracts a digital watermark from the image input by the image input unit 10 using the digital watermark extracting method input by the image information input unit 12. The encryption / decryption unit 64 regards the extracted digital watermark as a digital signature, and decrypts the digital signature using a method for decrypting the digital signature input by the image information input unit 12. The falsification determination unit 66 includes data obtained by decryption by the encryption / decryption unit 64 and image identification information I input by the image information input unit 12.
The presence or absence of tampering is determined by detecting whether or not D matches.

FIG. 7 is a flowchart of the image falsification determination method. The image tampering determination method performed by the image tampering determination device 90 will be described with reference to FIG.

The image input section 11 inputs an image (S22).
0). The image information input unit 12 inputs a digital watermark extraction method, a digital signature decryption method, and an image identification information ID for the image input by the image input unit 10 (S222).

The digital watermark extracting unit 62 extracts a digital watermark from the image based on the digital watermark extracting method input by the image information input unit 12 (S224). Encryption / decryption unit 64
Regards the digital watermark extracted by the digital watermark extracting unit 62 as the value of the digital signature D (ID, sk) and decrypts the digital watermark using the public key pk. The encryption / decryption unit 64 knows the encryption function E from the decryption method input by the image information input unit 12, decrypts the digital signature D (ID, sk) by the encryption function E using the public key pk, and decrypts the digital signature D (ID, sk). E (D (ID, sk), pk) is obtained as data (S226).

The falsification determination unit 66 checks whether or not the data E (D (ID, sk), pk) decrypted by the encryption / decryption unit 64 is equal to the image identification information ID input by the image information input unit 12 ( S228). If they are equal, it is determined that the image has not been tampered with (S230), and if they are not equal, it is determined that the image has been tampered with (S23).
2).

According to the image tampering detection apparatus of this embodiment, the contractor extracts the digital watermark from the image submitted to the orderer, regards the digital watermark as a digital signature, and extracts the image identification information by decoding. Can be. By collating the obtained image identification information with the image identification information previously notified by the administrator of the lab system, it is possible to detect whether or not the image has been tampered with.

FIG. 8 is a configuration diagram of an image falsification determination apparatus according to the third embodiment of the present invention. The basic configuration and operation of the image tampering determination device of the present embodiment are the same as those of the image tampering determination device of the second embodiment shown in FIG. This embodiment differs from the second embodiment in that an electronic computer such as a personal computer or a workstation is used as the processing unit 60 of the image tampering determination device.

The hardware configuration of the processing unit 60 will be described with reference to FIG. CPU 30 has ROM 32 and R
It operates based on the program stored in AM34.
Data is input by the user via an input device 31 such as a keyboard and a mouse. The hard disk 33 stores data such as images and a program for operating the CPU 30. The CD-ROM drive 35 is a CD-ROM 1
00 to read data or program
4, provided to at least one of the hard disk 33 and the CPU 30.

The functional configuration of software executed by the CPU 30 of the processing unit 60 is the same as that shown in FIG. 6, and the digital watermark detection module 162, the encryption / decryption module 164,
Falsification determination module 166.

The electronic watermark detection module 162, the encryption / decryption module 164, and the falsification determination module 166
Works on the computer to cause the CPU 30 to perform the processing of the digital watermark extraction unit 62, the encryption / decryption unit 64, and the falsification determination unit 66 in the image falsification determination device 90 of the second embodiment shown in FIG. Since the functions and operations are the same, the description will be omitted. These software are stored in a recording medium such as the CD-ROM 100 and provided to the user. The software is installed on the hard disk 33 from the recording medium, read out to the RAM 34, and executed by the CPU 30.

CD-ROM 10 as an example of a recording medium
0 may store some or all of the functions of the processing unit 20 or the processing unit 60 described in the present application. The CD-ROM 100 can store some or all of the functions of other devices. These programs may be read directly from the recording medium to the RAM 34 and executed.

As a recording medium, in addition to the CD-ROM 100, an optical recording medium such as a DVD or a PD, a magnetic recording medium such as a floppy disk or a mini disk (MD),
And the like, a magneto-optical recording medium, a tape-shaped recording medium, a nonvolatile semiconductor memory card, and the like can be used. The recording medium storing the above program is used only for manufacturing a digital watermark synthesizing apparatus and an image falsification judging apparatus, and the production and sale of such a recording medium as a business based on the present application. Clearly constitutes a patent infringement.

As described above, according to the digital watermark synthesizing apparatus of the first embodiment, a digital signature for image identification information is created for image data of a photograph of a contractor,
It can be combined with an image as a digital watermark.

When the contractor alters the image, the information of the digital watermark is destroyed, so that a trace of the alteration can be left on the image. The combined digital watermark cannot be easily taken out by the contractor. Even if a digital watermark is extracted, the extracted digital watermark is a digital signature of the image identification information and cannot be easily decoded.

By using different information for each orderer, different information for each order, and different information for each image as the image identification information, the security of the digital signature embedded as a digital watermark is changed to alter the security. The effect of prevention can be improved.

According to the image tampering detection apparatus of the second embodiment, the contractor extracts the digital watermark from the image submitted to the orderer, regards the digital watermark as a digital signature, and decodes the image identification information. Can be taken out.
The obtained image identification information is collated with the image identification information previously notified by the administrator of the laboratory system, and it is possible to detect whether or not the image has been tampered with.

Although the present invention has been described with reference to the embodiment, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is apparent to those skilled in the art that various changes or improvements can be added to the above embodiment. It is apparent from the description of the appended claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

[0088]

As is apparent from the above description, according to the present invention, a digital watermark is combined with an image photographed by a contractor at the request of the contractor, and the image submitted by the contractor is falsified. Can be determined.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a system that determines whether an image has been tampered with using a digital watermark synthesizing device 80 and an image tampering determination device 90 according to the present invention.

FIG. 2 is a configuration diagram of a digital watermark synthesizing device 80 according to the first embodiment of the present invention.

FIG. 3 is a functional block diagram of a processing unit 20;

FIG. 4 is a flowchart of a digital watermark synthesizing method.

FIG. 5 is a configuration diagram of an image tampering determination device 90 according to a second embodiment of the present invention.

FIG. 6 is a functional block diagram of a processing unit 60.

FIG. 7 is a flowchart of an image falsification determination method.

FIG. 8 is a configuration diagram of an image falsification determination device according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Image input part 12 Image information input part 20 Processing part 22 Encryption part 24 Digital watermark synthesizing part 26 Image information notification part 26 40 Recording part 50 Output part 60 Processing part 62 Digital watermark extraction part 64 Encryption decryption part 66 Falsification judgment part 80 Digital watermark synthesizing device 90 Image alteration judging device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04L 9/32 H04L 9/00 673E F-term (Reference) 5B057 AA20 CE08 5C076 AA14 BA06 5J104 AA07 AA09 AA14 KA01 KA05 LA03 LA06 NA02 NA05 NA29 NA32 PA14

Claims (11)

[Claims] 1. An electronic watermark synthesizing apparatus for synthesizing an electronic watermark with an image, comprising: an image input unit for inputting the image; and an encryption generating unit for generating encryption information obtained by encrypting image identification information for identifying the image. An electronic watermark synthesizing unit for synthesizing the cryptographic information as an electronic watermark with the image; an image recording unit for recording the image synthesized by the electronic watermark synthesizing unit; an extracting method of the electronic watermark; Method,
And an image information notifying section for notifying the image identification information. 2. The apparatus according to claim 1, wherein the encryption creating unit creates the encryption information by creating a digital signature of the image identification information based on a secret key in a public key encryption system. The electronic watermark synthesizing apparatus according to the above. 3. The digital watermark synthesizing apparatus according to claim 2, wherein the image identification information is identification information that differs for each requester of the image recording. 4. The electronic watermark synthesizing apparatus according to claim 2, wherein the image identification information is identification information that differs for each order of recording of the image. 5. The digital watermark synthesizing apparatus according to claim 2, wherein the image identification information is identification information different for each image. 6. An image tampering determination device that determines whether an image has been tampered with, an image input unit that inputs the image, a digital watermark extraction method of the image, and an encryption / decryption method of decrypting the encryption of the digital watermark. And an image information input unit for inputting image identification information for identifying the image; a digital watermark extracting unit for extracting a digital watermark of the image based on the digital watermark extracting method; and An encryption / decryption unit that decrypts the digital watermark; and a tampering determination unit that determines whether the image has been tampered with by comparing the decrypted data decrypted by the encryption / decryption unit with the image identification information. An image tampering determination device characterized by the following. 7. The encryption / decryption unit obtains the decrypted data by regarding the digital watermark as a digital signature and decrypting the digital signature based on a public key in a public key cryptosystem. An image falsification determination device according to claim 6. 8. The apparatus according to claim 7, wherein the image identification information is identification information that differs for each photographer of the image or identification information that differs for each image. 9. An image tampering determination method for determining whether an image has been tampered with, comprising the steps of: inputting the image, extracting a digital watermark of the image, decrypting the digital watermark, and identifying the image. Inputting identification information to extract the digital watermark of the image based on the digital watermark extracting method, and extracting the decoded data by decoding the digital watermark based on the decoding method; An image tampering determination method, comprising determining whether the image has been tampered with by comparing the image identification information. 10. The method according to claim 9, wherein the identification information of the image is identification information that differs for each photographer of the image or identification information that differs for each image. 11. A recording medium storing a computer program for judging whether or not an image has been tampered, wherein the program comprises: an image input module for causing the computer to input the image; Digital watermark extraction method,
A decryption method for decrypting the encryption of the digital watermark, an image information input module for inputting image identification information for identifying the image, and a digital watermark extraction module for extracting a digital watermark of the image based on the digital watermark extraction method. Determining whether the image has been tampered with by comparing the decryption data decrypted by the cryptographic decryption module with the image identification information based on the decryption method. And a falsification determination module.