Method for generating digital watermarks for electronic documents
First Claim
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1. A method for generating a digital watermark for an electronic document, comprising:
- determining a first hash value of the document;
generating the watermark as a function of a proof of identity identification and the first hash value of the document;
providing a secret key for making the watermark visible;
embedding the watermark in the document;
restoring the document to an original state by removing the watermark using the secret key;
determining a hash value of the restored document; and
verifying ownership of the document by comparing the hash value of the restored document and the first hash value,wherein the generating the watermark step includes generating the watermark as a function of the proof of identity identification, the first hash value of the document, and an authentic time stamp.
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Abstract
Verification of true authorship on the basis of digital watermarks is described. The digital watermark can be provided with the proof of identity id and/or with the hash value h(m) of the document and/or with a time value t.
18 Citations
6 Claims
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1. A method for generating a digital watermark for an electronic document, comprising:
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determining a first hash value of the document; generating the watermark as a function of a proof of identity identification and the first hash value of the document; providing a secret key for making the watermark visible; embedding the watermark in the document; restoring the document to an original state by removing the watermark using the secret key; determining a hash value of the restored document; and verifying ownership of the document by comparing the hash value of the restored document and the first hash value, wherein the generating the watermark step includes generating the watermark as a function of the proof of identity identification, the first hash value of the document, and an authentic time stamp. - View Dependent Claims (2, 3, 4)
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5. A method for generating a digital watermark for an electronic document, comprising:
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determining a first hash value of the document; generating the watermark as a function of a proof of identity identification and the first hash value of the document; providing a secret key for making the watermark visible; embedding the watermark in the document; restoring the document to an original state by removing the watermark using the secret key; determining a hash value of the restored document; and verifying ownership of the document by comparing the hash value of the restored document and the first hash value, wherein the generating the watermark step includes generating the watermark as a function of the proof of identity identification, the first hash value of the document, and an authentic time stamp. - View Dependent Claims (6)
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Specification