| 摘要 |
A technique for identifying whether information in an original document has been altered in a copy thereof is described. A creator identifies the pertinent information in an original document, where the pertinent information may include image and text information. This pertinent information is encrypted and reduced to a verification mark such which is added to the original document. The pertinent information can be compressed prior to encryption. A verifying party receives a copy of the document along with an appended verification mark. The verification mark is decrypted and the information contained in the verification mark is reproduced and compared with the information contained in the copy. Any discrepancy between information contained in the verification mark, which is known to be true, with information in the copy indicates that the copy may have been altered.
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