Integrity protection for electronic document with combination of visible, invisible-robust and invisible non-robust watermarks for on-line verification

摘要

Procedure allows legally relevant data: a signature, write pressure and write duration for signature to be inserted in electronic document in form of visible and invisible digital watermark. Facsimile of signature is used as visible watermark. Data is also used as invisible-robust and invisible non-robust digital watermarks on document. Document is printed out and signed again, repeat signature is used as new digital watermark.