Signing a password protected document

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   Hi all,I've been required to digitally sign an already password protected document with no success.
I'm using QuickPdf v11.13. So far I can digitally sign unprotected PDFs, with or without images, with no problem. Basically:
- NewSignProcessFromFile(...)
- SetSignProcessPFXFromFile(...)
- SetSignProcessFieldBounds(...)
- SetSignProcessFieldImageFromFile(...)
- EndSignProcessToFile(SignedPdf)  // SignedPdf= new signed PDF
res= GetSignProcessResult(...).  // OK

But the same process with a password protected PDF does not sign the resulting PDF. This protected PDF already has an empty signature field and has no constraints filling fields, signing...

The original protected PDF (password; owner) is
https://we.tl/t-x0JuwBxfqQ
The resulting not signed PDF is:
https://we.tl/t-uh06rFQf1r

Can anyone guide me or give me any hint?
Thank you very much

Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
Bigun Members Profile Find Members Posts Beginner Joined: 23 Jul 19 Location: Irun Status: Offline Points: 9	Post Options Post Reply Quote Bigun Report Post Thanks(0) Quote Reply Topic: Signing a password protected document Posted: 24 Jul 19 at 12:25PM
	Hi all, I've been required to digitally sign an already password protected document with no success. I'm using QuickPdf v11.13. So far I can digitally sign unprotected PDFs, with or without images, with no problem. Basically: - NewSignProcessFromFile(...) - SetSignProcessPFXFromFile(...) - SetSignProcessFieldBounds(...) - SetSignProcessFieldImageFromFile(...) - EndSignProcessToFile(SignedPdf) // SignedPdf= new signed PDF res= GetSignProcessResult(...). // OK But the same process with a password protected PDF does not sign the resulting PDF. This protected PDF already has an empty signature field and has no constraints filling fields, signing... The original protected PDF (password; owner) is https://we.tl/t-x0JuwBxfqQ The resulting not signed PDF is: https://we.tl/t-uh06rFQf1r Can anyone guide me or give me any hint? Thank you very much

Ingo Members Profile Find Members Posts Moderator Group Joined: 29 Oct 05 Status: Offline Points: 3524	Post Options Post Reply Quote Ingo Report Post Thanks(0) Quote Reply Posted: 24 Jul 19 at 8:33PM
	Hi Bigun, did you read the description regarding NewSignProcessFromFile? https://www.debenu.com/docs/pdf_library_reference/NewSignProcessFromFile.php There you can read: "...Creates a new digital signature process using a file as the source document...". There is a password as parameter ;-) If the password is protected the original owner wanted to protect it ;-) If it's only the main password you can do it this way: // ... QP.LoadFromFile(FileName, ''); If QP.EncryptionStatus > 0 Then QP.Decrypt; // ... then you can begin with your signing process. Cheers and welcome here, Ingo
	Cheers, Ingo

Bigun Members Profile Find Members Posts Beginner Joined: 23 Jul 19 Location: Irun Status: Offline Points: 9	Post Options Post Reply Quote Bigun Report Post Thanks(0) Quote Reply Posted: 26 Jul 19 at 8:49AM
	Thank you for your answer Ingo, but I'm afraid I'm already starting the signing process using it: int SignProcessID= QP->NewSignProcessFromFile(sSourcePdf, sOwnerPassword); ... If I decrypt SourcePdf as you suggest, the signature process goes well but I'm not able to Encrypt the resulting signed PDF, so I get a signed unprotected PDF: int Permisos= QP->EncodePermissions(1, 0, 0, 0, 1, 1, 0, 1); int iRes= QP->Encrypt(sPassOwner, "", Strength, Permisos); QP->SetSignProcessPFXFromFile(SignProcessID, PFXFileName, PFXPassword); ... QP->EndSignProcessToFile(SignProcessID, sOutput); // <== should be signed and password protected On the other hand, if I don't decrypt it, the resulting file, though protected, does not get signed. I'll keep trying. Thanks for your help!!

Ingo Members Profile Find Members Posts Moderator Group Joined: 29 Oct 05 Status: Offline Points: 3524	Post Options Post Reply Quote Ingo Report Post Thanks(0) Quote Reply Posted: 26 Jul 19 at 8:52PM
	Hi Bigun, here's a kb-document from Debenu: https://www.debenu.com/kb/add-visual-digital-signature-to-a-pdf-programmatically/ With this link you'll find interesting hints from Rowan: http://www.quickpdf.org/forum/visible-digital-signature_topic2563.html A quick read through the content lt me think that signing doesn't need a password? If you simply rewrite the pdf the signature is broken and all readers are telling that the signature in the loaded pdf was broken...
	Cheers, Ingo