Please help with PXC_SignDocumentXXX in VB.NET

[ondrejb]

Hello,
I spent several hours trying to make any of the PXC_SignDocumentXXX funtions work but with no luck.

I have a simple test scenario - create new PDF document, add a new page and a picture on the page (our intend is to use PDF for e-archiving of scanned documents). Then I add another new page to put the sign on and try to sign the document - which failes.
Without trying to sign the document, I am able to save it and view it in the Adobe Reader.


---------------------------------------------------
#My 1. approach - using PXC_SignDocumentW

<DllImport("pxclib40")> _
Public Function PXC_SignDocumentW( _
ByVal pdf As Integer _
, ByVal PCertt As IntPtr _
, ByVal page As Integer _
, ByVal rect As PXC_RectF _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszReason As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszLocation As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszContactInfo As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszImageFile As String _
, ByVal dwFlags As Integer _
) As Integer
End Function

...

Dim cert As New X509Certificate2("123pass123456.pfx", "123456")
PXC_SignDocumentW( _
myPdfDoc _
, cert.Handle _
, myPage _
, pageSize _
, "test" _
, "anywhere" _
, "test@test" _
, "" _
, 0) _

=> fails with an AccessViolationException



---------------------------------------------------
#My 2. approach - using PXC_SignDocumentBufW


<DllImport("pxclib40")> _
Public Function PXC_SignDocumentBufW( _
ByVal pdf As Integer _
, ByVal pPXCBuf() As Byte _
, ByVal nPFXLen As Integer _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszPFXPassword As String _
, ByVal page As Integer _
, ByVal rect As PXC_RectF _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszReason As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszLocation As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszContactInfo As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszImageFile As String _
, ByVal dwFlags As Integer _
) As Integer
End Function

...

' get PKCS#7
Dim cert As New X509Certificate2("123pass123456.pfx", "123456")
Dim certColl As New X509Certificate2Collection
certColl .Add(cert)
Dim bin() As Byte = certColl .Export(X509ContentType.Pkcs7, "123456")

' sign PDF document
PXC_SignDocumentBufW( _
myPdfDoc _
, bin _
, bin.Length _
, "123456" _
, ByVal page As Integer _
, ByVal rect As PXC_RectF _
, myPage _
, pageSize _
, "test" _
, "anywhere" _
, "test@test" _
, "" _
, 0)

=> fails with an undocumented error code: -2081153022



---------------------------------------------------
#My 3. approach - using PXC_SignDocumentUsingPFXW

<DllImport("pxclib40")> _
Public Function PXC_SignDocumentUsingPFXW( _
ByVal pdf As Integer _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszPFXFile As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszPFXPassword As String _
, ByVal page As Integer _
, ByVal rect As PXC_RectF _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszReason As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszLocation As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszContactInfo As String _
, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpwszImageFile As String _
, ByVal dwFlags As Integer _
) As Integer
End Function

...

PXC_SignDocumentUsingPFXW( _
myPdfDoc _
, "123pass123456.pfx" _
, "123456" _
, ByVal page As Integer _
, ByVal rect As PXC_RectF _
, myPage _
, pageSize _
, "test" _
, "anywhere" _
, "test@test" _
, "" _
, 0)


=> fails with an AccessViolationException


---------------------------------------------------

I tried all functions with several certificates, including the one provided in this example project:
https://forum.pdf-xchange.com/ ... 14&p=17427

I also tried all versions with several values for dwFlags, passing NULL (Nothing in VB) as lpwszImageFile and many other approaches I can't remeber...

I will be gratefull for any hint
Ondrej Bouda

---------------------------------------------------
My configuration:
* PDF-XChange PRO 4 SDK, build 4.0.0.150
* VB.NET 2008, ver. 9.0.30729.1 SP (with SP1)
* Win Vista Business SP1

[Ivan - Tracker Software]

Can you send me complete sample project which I can test here (without certificate for sure). Looks like trouble is into functions declarations.

[ondrejb]

Here is the sample project.
I noticed that the PXC_SignDocumentW and PXC_SignDocumentUsingPFXW don't throw AccessViolationException anymore - now they simply freeze instead...
Thank you for your effort!

[Ivan - Tracker Software]

Sorry, I'm not so familiar with VB, but when you create a PFX from the certificate, it isn't a valid PFX file. You can check this - just save the buffer you get here:

Code: Select all

Dim cert() As Byte = certcoll.Export(X509ContentType.Pkcs7, CertPassw)

into the file with .pfx extension, and when try to open this file with Explorer instead of seeing the Certificate Import Wizard you will see an error message window:

"Invalid Public Key Security Object File. This file is invalid for use as the following: Personal Information Exchange".

But when I use signing via AddSign_UsingPFXW, all works fine.

[ondrejb]

Ad AddSign_UsingPFXW - I tested this function on 3 other computers with the same result: Task manager shows that the application uses 50% CPU, application will never finish...
2x test config: Win Vista Bussiness + .NET 3.5 + all OS updates
1x test config: Win XP Professional + .NET 3.5 + all OS updates
1x test config: clean installation Win XP Professional + .NET 3.5 only

Is there any external required library that I could be missing?
Could the problem be caused by the .NET 3.5 enviroment?

Ad PXC_SignDocumentBufW - according to the documentation, the certificate should come in the PKCS#7 format. Should you save the buffer as ".p7b", you will be able to import it:

Code: Select all

IO.File.WriteAllBytes("t-cert.pk7", cert)

Note: Windows uses the ".p7b" extension for files containing PKCS#7, and ".pfx" for PKCS#12 - for this reason you weren't able to import a ".pfx" file with ".p7b" content.

I tried to use the function directly with the PKCS#12 file content (without converting it to PKCS#7) and I got the same freezing as with the other functions:

Code: Select all

Dim cert() As Byte = IO.File.ReadAllBytes("123pass123456.pfx")

It seems, that there is a mistake in the documentation and the PXC_SignDocumentBufW function requires rather a PKCS#12 content - is it so?

[Ivan - Tracker Software]

Yes, PKCS#12 should be, not PKCS#7.

Freezing of Sing functions can be a result of wrong rect passed to them -- looks like problem is into the routing which calculates font's sizes for strings into signature appearance.

[ondrejb]

Well, I tried to play with rect values - small/large rect height and width, swapping left/right and bottom/top, I tried to pass the values from the example in the documentation - but with no luck, I get always the same 'freezing'.
Any other idea?

I'd suppose that if the function gets wrong parameters, it should abort with an error code but never freeze...

[ondrejb]

Any progress in this?
Did you try to compile the project and run the .exe on a clean WinXP installation (with only .NET 3.5 installed)?

At this time, we are evaluating the PDF-XChange PRO SDK if it is suitable for our applications and untill this it looked good...

[Corwin - Tracker Sup]

Hello.
Please, look at the sample project which is attached to this message.
HTH

[ondrejb]

Thank you very much, it worsk!

The problem was in the PXC_SignDocumentXXX function declarations:

Code: Select all

<DllImport("pxclib40")> _
Public Function PXC_SignDocumentUsingPFXW( ... )

where the rectangle should be passed by reference:

Code: Select all

 ByVal rect As PXC_RectF  ' wrong - does not work
 ByRef rect As PXC_RectF  ' works fine

[John - Tracker Supp]

Pleased all is well