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Is there a way to append a page to an e-signed PDF without losing the digital signature using iTextSharp? In real estate you often have a contract and addendum, both esigned in a seperate process, but users would like to have them attached in one single pdf file. The problem is that once you add a page to an e-signed doc, the e-signature disappears.

It makes sense since the signature means a user has made an agreement based on what was presented to them, but if you're just appending another esigned addendum, or even another unsigned page for them to sign in addition to the previously signed page, I would hope they is something that takes this into account and keeps track of envelope changes for any legal reasons

Brian Lorraine
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  • No, it is not possible, see [this answer](https://stackoverflow.com/a/16711745/1729265). BUT you can create a portable collection / portfolio PDF to which you attach both the contract and the addendum. – mkl Oct 30 '19 at 05:43
  • By the way, *"once you add a page to an e-signed doc, the e-signature disappears"* - this sounds weird, usually the signature would become invalidated (which a signature validation would show) but it wouldn't disappear. Your code for testing this seems to have been destructive to an unnecessary degree. – mkl Oct 30 '19 at 05:48
  • It actually depends on which client its viewed in. All I'm doing is just appending two documents. Chrome wont show the signatures anymore once you do that. – Brian Lorraine Oct 30 '19 at 11:59

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Digitally signing a document means that the software validates its content and appends a "seal" using a certificate. That means that when the file is signed, its content is locked and any modification to the content of the file would result in an invalidation of the digital signature (not the same as eSignature, which is more procedural in nature). DocuSign enforces this and as a result would invalidate both signatures (digital and electronic) when the file is modified. You can send a new envelope with the new file to be digitally signed if you want, but you cannot modify a signed digitally document after the fact.

Inbar Gazit
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