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When digitally signing an electronic document (e.g. a PDF or MS Word) the digital signature is apparent in one of the document's pages or as a property indicated by the reader application (e.g. in MS Word a red "stamp" indicates a valid signature.)

In a paperless environment this may be completely adaquate but in a mixed setting the documents may still have to be stored in printed form. "Old-fashioned" document signing confirming every individual page of the document requires from the signers to put a signature on every page.

Having a document that has been electronically signed how can somebody do something similar, i.e. include a type of "singature", on each page of the printed version?

  • What software are you using? Some software supports printing out digital signatures on signed files. – mzhaase Sep 12 '16 at 11:17
  • Right now it's Adobe Acrobat Reader or MS Office. Any other software also welcome – George Sep 12 '16 at 11:50
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    You would probably have to use an enterprise scale document management system to do it properly. You could print an encoded image (probably a 2d barcode). In addition, some PDF editors (including Acrobat Pro) have managed signatures that securely allow an image (normally a persons actual signature scanned in or written on a tablet) to be added along side the digital signature. – Julian Knight Sep 12 '16 at 12:29
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I have experimented this with digital invoices. What we came up with was to create a small text representation of the invoice data, digitally sign it and include that signature as a QRCode in the document itself (we included the actual data alongside since it allowed for easy machine reading).

Now, this approach is only usable if you can generate such a summary in a meaningful and consistent way: for general purpose documents, it could be hard to apply, especially if they contain images.

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It's theoretically possible for software to put a 'digital signature' in the form of a string of readable characters on each page of text (for example, in the footer of each page).

But to verify it, you would have to manually type the whole page into a computer, as well as the signature string of characters. That wouldn't be very practical.

  • Scanning + OCR? – domen Sep 12 '16 at 15:20
  • It would work only with plaintext. add images and it's dead (example : patents) – zr_ifrit Sep 13 '16 at 7:21
  • @domen the OCR has to be very accurate. If one character is misread, all the signature is invalid. – zr_ifrit Sep 13 '16 at 7:24
  • @Zrechim same goes for typing. – domen Sep 13 '16 at 7:36
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A generated text or stamp has no value on a printed document. The "most used" solution is to put a datamatrix image (it looks like a qr code, but different) on the document. This datamatrix contains the data of the signed document. 2 problems :

  • it applies only on certain types of docs (bills...). Only the different important informations are signed.

  • you have to use a special reader to decode it

  • does not work with images

The full document would be signed as an image, but it is very difficult to know what the printed version will look like (depending on the printer, black and white vs color, etc.)

An example of norm is 2d-doc (french).

Note : I work for the creators of 2ddoc

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