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Signing PDF/A files

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Create virtual disks backed by memory or custom location, expose disk images as disks and more.
#17763
Posted: 10/06/2011 10:56:50
by ingbabic  (Standard support level)
Joined: 09/27/2011
Posts: 114

Hello
After I signed PDF/A document (document that conforms PDF/A-1b standard) with your library it was not any more PDF/A!! Please can u check this. I have used your sample application for signing PDFs with PADES standard. In attachment (in zip)you have valid PDF/A-1b document(this you can test on following site http://www.datalogics.com/products/callas/callaspdfA-onlinedemo.asp).

I need to be able to sign with PADES, PDF/A documents and they have to stay PDF/A after signing.


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#17764
Posted: 10/06/2011 11:24:31
by Ken Ivanov (EldoS Corp.)

Thank you for contacting us.

PDF/A standard exposes quite strict requirements, so some of the transformations performed by SecureBlackbox might lead to breakdown of PDF/A compatibility. Still, you can preserve the compatibility by tuning the components up in the proper way.

As known, PDF/A in particular requires that
- the document should be self-contained,
- no encryption should be used,
- no LZW and JPEG2000 compression should be used.

Therefore, you must not use JPEG or JPEG2000 backgrounds when creating signatures. By using invisible signatures or vector widgets the PDF/A compatibility will be preserved.
#17765
Posted: 10/06/2011 11:35:28
by ingbabic  (Standard support level)
Joined: 09/27/2011
Posts: 114

I have used invisible signature. I did not check anything in the form. I wanted just plain PADES signed PDF document. Please can you test this?
#17766
Posted: 10/06/2011 11:43:04
by Ken Ivanov (EldoS Corp.)

Hmm, according to the information on the web site you mentioned (http://www.datalogics.com/products/ca...edemo.asp) they only check compatibility against PDF/A-1 standard. However, provisions for PAdES digital signatures are only supported in PDF/A-2.
#17767
Posted: 10/06/2011 11:58:27
by ingbabic  (Standard support level)
Joined: 09/27/2011
Posts: 114

Thank you very much for information. Can you please tell me how (which tool, or site) to validate pdf against PDF/A-2?
#17770
Posted: 10/06/2011 14:39:32
by Ken Ivanov (EldoS Corp.)

Frankly speaking, I am not aware of such tools / sites. Yet, we'd be thankful to everyone who could share this information here with all of us.
#17771
Posted: 10/07/2011 01:52:08
by ingbabic  (Standard support level)
Joined: 09/27/2011
Posts: 114

Hmm, something is still wrong...
After I tried with PADES demo, I give a try with TinySigner (also sample app that comes with SBB). Here I will show thru which lines of code it passes:
Code
string TempPath = Path.GetTempFileName();
System.IO.File.Copy(tbSource.Text, TempPath, true);
FileStream F = new FileStream(TempPath, FileMode.Open, FileAccess.ReadWrite);
Document.Open(F);
int index = Document.AddSignature();
TElPDFSignature Sig = Document.get_Signatures(index);
Sig.Handler = PublicKeyHandler;
Sig.AuthorName = tbAuthor.Text;
Sig.SigningTime = DateTime.Now.ToUniversalTime();
Sig.Reason = "";
Sig.Invisible = true;
Cert = SystemStore.get_Certificates(cbSystemCerts.SelectedIndex);
CertStorage.Clear();
CertStorage.Add(Cert, true);
PublicKeyHandler.CertStorage = CertStorage;
PublicKeyHandler.SignatureType = SBPDFSecurity.TSBPDFPublicKeySignatureType.pstPKCS7SHA1;
PublicKeyHandler.CustomName = "Adobe.PPKMS";
Document.Close(Success);
F.Close();
File.Copy(TempPath, tbDest.Text, true);
MessageBox.Show("Signing process successfully finished", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
File.Delete(TempPath);
this.Close()


After this document is NOT PDF/A any more and we didn't use PADES. DataLogic site shows syntax problem:
Quote
Syntax problem: Indirect object “endobj” keyword not preceded by an EOL marker

In attachment you have both documents. The document that I'm signing (PDF/A-1B), and correctly signed document, only now not PDF/A.

This should not happen, shouldn't it?


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#17773
Posted: 10/07/2011 05:15:42
by Dmytro Bogatskyy (EldoS Corp.)

Quote
Quote
Syntax problem: Indirect object “endobj” keyword not preceded by an EOL marker

In attachment you have both documents. The document that I'm signing (PDF/A-1B), and correctly signed document, only now not PDF/A.

What version of SecureBlackbox are you using?
As far as I remember, the similar issue was fixed in one of the last builds.
#17774
Posted: 10/07/2011 05:44:38
by ingbabic  (Standard support level)
Joined: 09/27/2011
Posts: 114

I am using 9.0.203.
#17782
Posted: 10/07/2011 11:52:12
by Dmytro Bogatskyy (EldoS Corp.)

Quote
I am using 9.0.203.

Please try to sign with the latest release 9.1.207
Also by EldoS: MsgConnect
Cross-platform protocol-independent communication framework for building peer-to-peer and client-server applications and middleware components.

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