Image encryption/decryption apparatus, method and program

• US 20090323950A1
• Filed: 05/29/2008
• Published: 12/31/2009
• Est. Priority Date: 05/30/2007
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kuraki, Kensuke, Anan, Taizo, NAKAGATA, Shohei
• Granted Patent: US 8,515,062 B2
• Time in Patent Office: Days
• US Class Current: 380/243
• 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:

an encryption region specifying unit that specifies a partial region to be encrypted from the digital image;

an image conversion unit that converts the partial region selected by the encryption region specifying unit into a processing image based on an encryption key; and

a pixel value conversion unit that generates a conversion image by regularly converting a pixel value of the processing image converted to specify a position of the partial region.

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 image conversion unit divides the partial region into a plurality of micro regions and rearranges the plurality of divided micro regions based on the encryption key.

4. The image encryption apparatus according to claim 1, wherein the image conversion unit converts the partial region by an arbitrary compression method into compressed data and arranges 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 pixel value conversion unit generates the conversion image 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 image encryption apparatus further comprises a marker addition unit that generates the encryption image by adding a specific marker to the conversion image generated by the pixel value conversion unit to specify the position of the 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 image encryption apparatus further comprises a check mark addition unit that adds a specific check mark for verifying a validity of decryption of the encryption image before the partial region is specified by the encryption region specifying unit.

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. An image decryption apparatus that decrypts an encryption image encrypted by an image encryption apparatus according to claim 6, the image decryption apparatus comprising:

a marker detection unit that detects a specific marker added to the encryption image specifying a position of an encrypted partial region;

an encryption region detection unit that detects an encrypted partial image region based on the maker detected by the marker detection unit;

an encryption position detection unit that detects an encryption position in which a pixel value is regularly converted in the encrypted partial image region; and

a decryption unit that decrypts the encrypted partial image region into a digital image based on the encryption position and a decryption key.

12. An image decryption apparatus that decrypts an encryption image encrypted by the image encryption apparatus according to claim 9, the image decryption apparatus comprising:

an encryption region detection unit that detects an encrypted partial image region;

an encryption position detection unit that detects an encryption position in which a pixel value is regularly converted in the encrypted partial image region;

a decryption unit that decrypts the encrypted partial image region into a digital image based on the encryption position detected by the encryption position detection unit and an decryption key; and

a check mark detection unit that detects a specific check mark verifying a validity of decryption from the digital image decrypted by the decryption unit.

13. An image decryption apparatus that decrypts an encryption image encrypted by the image encryption apparatus according to claim 9, the image decryption apparatus comprising:

a marker detection unit that detects a specific marker added to the encryption image specifying a position of an encrypted partial image region;

an encryption region detection unit that detects an encrypted partial image region based on the marker detected by the marker detection unit;

an encryption position detection unit that detects an encryption position in which a pixel value is regularly converted in the encrypted partial image region detected by the encryption region detection unit;

a decryption unit that decrypts the encrypted partial image region into a digital image based on the encryption position detected by the encryption position detection unit and an decryption key; and

a check mark detection unit that detects a specific check mark verifying a validity of decryption from the digital image decrypted by the decryption unit.

14. The image decryption apparatus according to claim 12, further comprising an encryption position correction unit that corrects the encryption position detected by the encryption position detection unit in a case when the check mark is not detected by the check mark detection unit.

15. The image encryption apparatus according to claim 1, wherein the encryption image is generated by printing the image encrypted by the image encryption apparatus according to claim 11, and by reading the printed image.

16. The image decryption apparatus according to claim 1, wherein the encryption image is generated by non-imaging the image encrypted by the image encryption apparatus according to claim 11, and digitally imaging the non-imaged image once again.

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

specifying a partial region from the digital image;

converting the selected partial region into a processing image based on an encryption key; and

generating a conversion image by regularly converting a pixel value of the converted processing image to specify a position of the partial region.

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 the position of the partial region.

20. A method of decrypting an encryption image encrypted by the image encryption method according to claim 17, the method comprising:

detecting a specific marker added to the encryption image specifying a position of an encrypted partial image region;

detecting an encrypted partial image region based on the detected marker;

detecting an encryption position in which a pixel value is regularly converted in the detected encrypted partial image region; and

decrypting the encrypted partial image region into a digital image based on the detected encryption position and a decryption key.

21. A method of decrypting an encrypted digital image encrypted by the image encryption method according to claim 17, the method comprising:

detecting an encrypted partial image region from the encrypted digital image;

detecting an encryption position in which a pixel value is regularly converted in the detected encrypted partial image region;

decrypting the encrypted partial image region into a digital image based on the detected encryption position and a decryption key; and

detecting a specific check mark verifying a validity of decryption from the decrypted digital image.

22. A method of decrypting an encryption image encrypted by the image encryption method according to claim 17, the method comprising:

detecting a specific marker added to the encryption image specifying a position of an encrypted partial image region;

detecting an encrypted partial image region based on the detected marker;

detecting an encryption position in which a pixel value is regularly converted in the detected encrypted partial image region;

decrypting the encrypted partial image region into a digital image based on the detected encryption position and a decryption key; and

detecting a specific check mark for verifying a validity of decryption from the decrypted digital image.

23. An image encryption apparatus encrypting a printed document, comprising:

a controller

digitally imaging the printed document into a digital image;

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

encrypting the partial region into an encrypted partial image region based on an encryption key;

specifying a position of the encrypted partial image region by regularly converting a pixel value of the encrypted partial image region; and

printing a document including an encrypted printed region corresponding to the encrypted partial image region.