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Second sign in PDF

Posted: 04/20/2016 09:11:08
by Martin ANDRES (Standard support level)
Joined: 09/25/2014
Posts: 18

we are using SecureBlackbox 12 to sign PDF files. It is working ok, the signature is created and it is displayed and validated in Acrobat Viewer DC.
But now we are having problems when we try to add a second signature in the PDF file previously signed with BalckBox. The PDF signature is broken and the content too.
We have the following scenarios:

- One PDF file signed with SecureBlackBox. Then, another signture is added using a plugin component called ProXSign (www.proxsign.com). The resulting PDF file has the signatures broken and the content too. I attach this file called second_signature_with_proxsign.pdf.

- One PDF file signed with JSignPDF (jsignpdf.sourceforge.net). Then, another signture is added using the plugin component ProXSign. In this case the resulting PDF is ok, with the two signatures ok and the content too. I attach this file called pdf_signed_with_jsignpdf.pdf.

So my question is: Is there any attribute in BlackBox that we can set when we sign the PDF so the proxsign can generate the second sign without any problem?. Why the signed PDF generated with JSignPDF can be sign again with proxsign and it worked ok?
Why there is a difference when we sign with Blackbox and JsignPDF?

I attach all the pdf files, you can download from http://wikisend.com/download/705226/signed_pdfs.zip .The original signed PDF signed with Baclbox is called blackboxsigned.pdf

I appreciate anny help on this matter.

Posted: 04/20/2016 13:07:30
by Dmytro Bogatskyy (Team)

Thank you for contacting us,

It seems that the problem is with ProXSign tool. It doesn't support signing of encrypted documents (your document is encrypted with empty user password). So, on signing it simply removes encryption and signs the pdf document, thus it invalidates previous signatures.
The workaround for this problem would be to remove encryption before adding the first signature, for this please see PDFBlackbox\Encryptor sample.



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