Tampering judgement system, encrypting system for judgement of tampering and tampering judgement method

• US 7,440,143 B2
• Filed: 11/26/2002
• Issued: 10/21/2008
• Est. Priority Date: 03/08/2002
• Status: Expired due to Fees

• Current Assignee: Oki Data Corporation (OKI Electric Industry Company Limited)
• Original Assignee: OKI Electric Industry Company Limited
• Inventors: Suzaki, Masahiko
• Primary Examiner(s): Poon; King
• Assistant Examiner(s): KAU, STEVEN Y
• Application Number:
  US10/303,911
• Publication Number:
  US 20030169456A1
• Time in Patent Office: 2,156 Days
• Field of Search: 358/3.28, 358/3.27, 358/464, 358/452, 358/453, 358/474, 358/538, 358/539, 358/527, 358/1.9, 382/190, 382/100, 382/198, 382/165, 382/176, 382/135, 382/181, 382/199, 382/201, 382/202, 382/203, 382/101, 382/162, 382/183, 382/232, 382/251, 380/281.44, 380/55, 380/54, 380/28, 380/201, 380/217, 380/258, 380/210, 713/165, 713/170, 713/175, 713/176, 713/193, 713/167, 713/164, 713/168, 713/190, 713/161, 713/150, 713/340
• US Class Current: 358/3.28
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• 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
• CPC Class Codes: H04L 9/0861 Generation of secret information including derivation or calculation of cryptographic keys or passwords

Abstract

A tampering judgement system is provided which is capable of easily checking whether or not a printed document has been tampered. An image feature information extracting section extracts image feature information from a document image. An image feature information embedding section gives image feature information integrally as original image feature information to a document and a document image output section outputs the information as a printed document. When the printed document is given to the tampering judgement system, the image data is read by a document image reading section. An image feature information extracting section extracts image feature information contained in a document being an object for judgement on tampering. An embedding information extracting section extracts original image feature information from image data. A judging section compares original feature information with image feature information contained in the printed document and if a difference between them exceeds a predetermined threshold value, the document is judged to have been tampered.

Claims

1. An encrypting system for judging whether or not a content of a specified document has been tampered comprising:

a document/image output device having a first original image feature information extracting section to divide an original document image of an original document into a plurality of original blocks and to respectively extract original image feature information from the plurality of original blocks, a first encryption key generating section to generate a first encryption key from the extracted original image feature information, a hidden information encrypting section to encrypt specified hidden information using the generated first encryption key, an encrypted information adding section to add the encrypted hidden information to said original document image, and an output section to output said original document image to which said encrypted hidden information has been added; and

a decoding device having an image reading section to read an image including a current document image of a current document and the encrypted hidden information, an encrypted information extracting section to divide the current document image into a plurality of current blocks to correspond to the plurality of original blocks and to respectively extract said encrypted hidden information from the current document, a second image feature information extracting section to extract second image feature information representing current features of an image from the current document, a second encryption key generating section to generate a second encryption key from the extracted second image feature information, and a decoding section to perform decoding processing on said extracted hidden information and the current features using the generated second encryption key.

2. The encrypting system according to claim 1, wherein said encrypted hidden information is able to be optically read.

3. The encrypting system according to claim 1, wherein the original image feature information represents an original feature data corresponding to one of the plurality of original blocks.

4. The encrypting system according to claim 1, wherein the image feature pattern is printed on a background region of the original document image where no characters exist.