Image verification system

• US 20030126444A1
• Filed: 12/20/2002
• Published: 07/03/2003
• Est. Priority Date: 12/28/2001
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Wakao, Satoru, Iwamura, Keiichi
• Granted Patent: US 7,162,637 B2
• Time in Patent Office: Days
• US Class Current: 713/176
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: H04N 1/32101 Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
• CPC Class Codes: H04N 2201/3226 of identification information or the like, e.g. ID code, index, title, part of an image, reduced-size image
• CPC Class Codes: H04N 2201/3233 of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/3235 Checking or certification of the authentication information, e.g. by comparison with data stored independently
• CPC Class Codes: H04N 2201/3236 Details of authentication information generation
• CPC Class Codes: H04N 2201/3239 using a plurality of different authentication information
• CPC Class Codes: H04N 5/77 between a recording apparatus and a television camera
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

If it is verified that image data generated by an imaging device has not been modified, a first verification device generates watermarked image data by embedding watermark for detecting a modified portion in the image data. The first verification device further generates second verification data (digital signature) of the watermarked image data. A second verification device verifies whether or not the image data has been modified, e.g., using the second verification data. If the image data has been modified, the second verification device detects what portion of the image data has been modified.

Claims

1. An image verification system comprising:

an imaging device having an image generating unit which generates image data, and a first verification data generating unit which generates first verification data using the image data and common information; and

a first image verification device comprising;

a first verification unit which verifies whether or not the image data has been modified, using the first verification data and the common information;

an embedding unit which, if said first verification unit verifies the image data has not been modified, embeds watermark data for detecting a modified portion in the image data so as to generate watermarked image data; and

a second verification data generating unit which generates second verification data using the watermarked image data and secret information.

2. An image verification system according to claim 1, wherein the common information corresponds to a secret key in a symmetric key cryptosystem.

3. An image verification system according to claim 1, wherein the secret information corresponds to a private key in a public key cryptosystem.

4. An image verification system according to claim 1, wherein if said first verification unit verifies that the image data has been modified, said second verification data generating unit prohibits generation of the second verification data.

5. An image verification system according to claim 1, further comprising:

a second image verification device comprising;

a second verification unit which verifies whether or not the watermarked image data has been modified, using the verification data and public information; and

a modified portion detecting unit which, if said second verification unit verifies that the watermarked image data has been modified, extracts the watermarked image data and detects the modified portion.

6. An image verification system according to claim 5, wherein the public information corresponds to a public key in a public key cryptosystem.

7. An image verification system according to claim 1, wherein said imaging device is a digital camera, a digital video camera, a scanner, a facsimile machine or a copying machine.

8. An image verification system according to claim 1, wherein said first image verification device is a memory medium comprising an IC or a microprocessor.

9. An image verification system comprising:

an imaging device including an image generating unit which generates image data, and a first verification data generating unit which generates first verification data using the image data and common information;

a transmitter which transmits the image data and the first verification data; and

a first image verification device that receives the image data and the first verification data transmitted by said transmitter, said first image verification device comprising;

a first verification unit which verifies whether or not the image data has been modified, using the first verification data and the common information;

an embedding unit which, if said first verification unit verifies that the image data has not been modified, embeds watermark data for detecting a modified portion in the image data so as to generate watermarked image data; and

a second verification data generating unit which generates second verification data using the watermarked image data and secret information.

10. An image verification system according to claim 9, wherein the common information corresponds to a secret key in a symmetric key cryptosystem.

11. An image verification system according to claim 9, wherein the secret information corresponds to a private key in a public key cryptosystem.

12. An image verification system according to claim 9, wherein, if said first verification unit verifies that the image data has been modified, said second verification data generating unit prohibits generation of the second verification data.

13. An image verification system according to claim 9, further comprising:

a second image verification device comprising;

a second verification unit which verifies whether or not the watermarked image data has been modified, using the second verification data and public information; and

a modified portion detecting unit which, if said second image verification unit verifies that the watermarked image data has been modified, extracts the electronic watermark data from the electronic watermarked image data and detects the modified portion.

14. An image verification system according to claim 13, wherein the public information corresponds to a public key in a public key cryptosystem.

15. An image verification system according to claim 9, wherein said imaging device is a digital camera, a digital video camera, a scanner a facsimile machine, or a copying machine.

16. An image verification system according to claim 9, wherein said first image verification device is a memory medium comprising an IC or a microprocessor.

17. An image verification system according to claim 9, wherein said first image verification device is a server computer with said transmitter as a client.

18. An image verification device comprising:

an image verification unit which verifies whether or not image data has been modified, using image data generated by an image device, first verification data and common information;

an embedding unit which, if said image verification unit verifies that the image data has not been modified, embeds watermark data for detecting a modified portion in the image data so as to generate watermarked image data; and

a verification data generating unit which generates second verification data of the image data using the watermarked image data and secret information.

19. An image verification device according to claim 18, wherein the common information corresponds to a secret key in a symmetric cryptosystem.

20. An image verification device according to claim 18, wherein the secret information corresponds to a private key in a public key cryptosystem.

21. An image verification device according to claim 18, wherein, if said image verification unit verifies that the image data has been modified, said verification data generating unit prohibits generation of the second verification data.

22. An image verification device according to claim 18, wherein said image verification device is a memory medium comprising an IC card or a microprocessor.

23. An image verification device according to claim 18, wherein said imaging device is a digital camera, a digital video camera, a scanner, a facsimile machine or a copying machine.

24. An image verifying method comprising the steps of:

verifying whether or not image data generated by an imaging device has been modified, using the image data, first verification data and common information;

if it is verified in the verifying step that the image data has not been modified, embedding watermark data for detecting a modified portion in the image data so as to generate watermarked image data; and

generating second verification data for the image data using the watermarked image data and secret information.

25. An image verifying method according to claim 24, wherein the common information corresponds to a secret key in a symmetric cryptosystem.

26. An image verifying method according to claim 24, wherein the secret information corresponds to a private key in a public cryptosystem.

27. An image verifying method according to claim 24, wherein, if it is verified in the first step that the image data has been modified, then said step of generating second verification data prohibits generation of the second verification data.

28. An image verifying method according to claim 24, wherein said image verifying method is executed in a memory medium comprising an IC or a microprocessor.

29. An image verifying method according to claim 24, wherein the image data is generated in one of a digital camera, a digital video camera, a scanner, a facsimile machine or a copying machine.

30. A medium storing a program executing an image verifying method, said image verifying method comprising the steps of:

verifying whether or not image data generated by an imaging device has been modified, using the image data, first verification data and common information;

if it is verified in the first step that the image data has not been modified, embedding watermark data for detecting a modified portion in the image data so as to generate watermarked image data; and

generating second verification data of the image data using the watermarked image data and secret information.