Image encryption/decryption apparatus, method and program

• US 8,515,062 B2
• Filed: 05/29/2008
• Issued: 08/20/2013
• Est. Priority Date: 05/30/2007
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Nakagata, Shohei, Kuraki, Kensuke, Anan, Taizo
• Primary Examiner(s): Zand, Kambiz
• Assistant Examiner(s): Durham, Imhotep
• Application Number:
  US12/129,266
• Publication Number:
  US 20090323950A1
• Time in Patent Office: 1,909 Days
• Field of Search: 380/54, 382/237, 382173-199, 382/232, 713/176
• US Class Current: 380/54
• CPC Class Codes: G09C 5/00 Ciphering apparatus or methods not provided for in the preceding groups, e.g. involving the concealment or deformation of graphic data such as designs, written or printed messages

Abstract

An image encryption apparatus encrypts a digital image by specifying a partial region from the digital image, converting the selected partial region into a processing image based on an encryption key, and specifying a position of the partial region by regularly converting a pixel value of the processing image.

Claims

1. An image encryption apparatus that encrypts a digital image, the image encryption apparatus comprising:

a computer processor to execute;

specifying a partial region to be encrypted from the digital image;

converting the partial region including micro regions into a processing image based on an encryption key; and

regularly converting a pixel value of the processing image in terms of a smaller converted region of a micro region to specify a position of the micro region of the partial region, thereby generating a conversion image that specifies positions of the micro regions.

2. The image encryption apparatus according to claim 1, wherein the digital image is digitally imaged by digitally imaging a non-digital image including a PDF format, an HTML and/or XML document, or an editable document, or any combinations thereof.

3. The image encryption apparatus according to claim 1, wherein the partial region is divided into the micro regions and the divided micro regions are rearranged based on the encryption key.

4. The image encryption apparatus according to claim 1, wherein the converting comprises converting the micro regions by an arbitrary compression method into compressed data and arranging each bit of the compressed data as a white pixel or a black pixel of an arbitrary size.

5. The image encryption apparatus according to claim 1, wherein the conversion image is generated by forming a nearly stripe pattern by converting the pixel value at a certain interval with respect to a transverse direction of the processing image and converting the pixel value at the certain interval with respect to a longitudinal direction of the processing image.

6. The image encryption apparatus according to claim 1, wherein the computer processor further adds a specific marker to the conversion image generated to specify a position of the converted partial region.

7. The image encryption apparatus according to claim 6, wherein the marker is shaped like a circle or a polygonal with a solid line in which there are a plurality of lines intersecting a circumference of the circle or the polygonal inside therein.

8. The image encryption apparatus according to claim 6, wherein a foreground of the marker is formed by pixel value conversion.

9. The image encryption apparatus according to claim 1, wherein the computer processor further adds a specific check mark for verifying a validity of decryption of the conversion image before the partial region is specified.

10. The image encryption apparatus according to claim 1, wherein the digital image is generated by converting non-digital data into the digital image.

11. The image encryption apparatus according to claim 6, wherein the conversion image is decryptable by:

detecting the specific marker added to the conversion image specifying a position of the converted partial region;

detecting a conversion position in which a pixel value is regularly converted in the converted partial region; and

decrypting the converted partial region into a digital image based on the conversion position and a decryption key.

12. The image encryption apparatus according to claim 9, wherein the conversion image is decryptable by:

detecting a converted partial region;

detecting a conversion position in which a pixel value is regularly converted in the converted partial region;

decrypting the converted partial region into a digital image based on the conversion position and an decryption key; and

detecting the specific check mark verifying a validity of the decryption.

13. The image encryption apparatus according to claim 9, wherein the conversion image is decryptable by:

detecting a specific marker added to the conversion image specifying a position of the converted partial region;

detecting a conversion position in which a pixel value is regularly converted in the converted partial region;

decrypting the converted partial region into a digital image based on the conversion position and an decryption key; and

detecting a specific check mark verifying a validity of the decryption.

14. The image decryption apparatus according to claim 12, wherein the detected conversion position is corrected in a case when the check mark is not detected.

15. The image encryption apparatus according to 11, wherein the conversion image to be decrypted is generated by reading a print of a conversion image.

16. The image encryption apparatus according to claim 11, wherein the conversion image to be decrypted is generated by non-imaging a conversion image, and digitally imaging the non-imaged image once again.

17. A method of encrypting a digital image, the method comprising:

specifying a partial region to be encrypted from the digital image;

converting the partial region including micro regions into a processing image based on an encryption key; and

regularly converting a pixel value of the processing image in terms of a smaller converted region of a micro region to specify a position of the micro region of the partial region, thereby generating a conversion image that specifies positions of the micro regions.

18. The method according to claim 17, wherein the digital image is digitally imaged by digitally imaging non-image data including a PDF format, an HTML and/or XML document, or an editable document, or any combinations thereof.

19. The image encrypting method according to claim 17, wherein the conversion image is generated by adding a specific marker to the generated conversion image specifying a position of the converted partial region.

20. The method according to claim 17, further comprising:

detecting a specific marker added to the conversion image specifying a position of the converted partial region;

detecting a conversion position in which a pixel value is regularly converted in the converted partial region; and

decrypting the converted partial region into a digital image based on the conversion position and a decryption key.

21. The method according to claim 17, further comprising:

detecting a converted partial region;

detecting conversion position in which a pixel value is regularly converted in the converted partial region;

decrypting the converted partial region into a digital image based on the conversion position and a decryption key; and

detecting the specific check mark verifying a validity of the decryption.

22. The method according to claim 17, further comprising:

detecting a specific marker added to the conversion image specifying a position of the converted partial region;

detecting a conversion position in which a pixel value is regularly converted in the converted partial region;

decrypting the converted partial region into a digital image based on the conversion position and a decryption key; and

detecting a specific check mark for verifying a validity of the decryption.

23. An apparatus for encrypting a printed document, comprising:

a controller configured to;

specifying a partial region to be encrypted from a digital image of the printed document;

converting the partial region including micro regions into a processing image based on an encryption key; and

regularly converting a pixel value of the processing image in terms of a smaller converted region of a micro region to specify a position of the micro region of the partial region, thereby generating a conversion image that specifies positions of the micro regions.