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Aaron
Apr 14, 2015, 10:05:42 PM4/14/15
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Q:
I've set the security permissions on my document to allow Document Assembly (adding/removing pages). But after I digitally sign the document with PDFNet, then look at the security permissions of the document in Acrobat (File->Properties->Security), Document Assembly is no longer allowed. Why did PDFNet turn this permission off?
A:
he signing process doesn't change those permission values. (If you use the CosEdit utility, downloadable from https://www.pdftron.com/pdfcosedit/index.html, you can see that the permissions at trailer/Encrypt/P; you can also find them from the security handler, see http://www.pdftron.com/pdfnet/samplecode.html#EncTest) It seems that Acrobat is showing that permission as false since the document is signed.
I've set the security permissions on my document to allow Document Assembly (adding/removing pages). But after I digitally sign the document with PDFNet, then look at the security permissions of the document in Acrobat (File->Properties->Security), Document Assembly is no longer allowed. Why did PDFNet turn this permission off?
A:
he signing process doesn't change those permission values. (If you use the CosEdit utility, downloadable from https://www.pdftron.com/pdfcosedit/index.html, you can see that the permissions at trailer/Encrypt/P; you can also find them from the security handler, see http://www.pdftron.com/pdfnet/samplecode.html#EncTest) It seems that Acrobat is showing that permission as false since the document is signed.
The fundamental issue seems to be that Document Assembly
(removing/adding pages) will necessarily invalidate a digital signature.
(This makes intuitive sense --- adding or removing a page turns a
document into another document entirely. Any digital signatures on the
document would need to be invalidated, otherwise the party who signed
the document would be legally bound to a contract they hadn't actually
agreed to.)
The following provides a useful bit of advice, suggesting to use PDF Portfolios to combine signed documents:
You can find sample code for creating PDF portfolios using the PDFNet SDK at:
https://www.pdftron.com/pdfnet/samplecode.html#PDFPackageReply all
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