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How to show visible Digital Signature using the PDF Blackbox in .NET

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Posted: 09/06/2012 02:26:49
by Vineet Luthra (Basic support level)
Joined: 09/06/2012
Posts: 3

i was trying to use your trail version of PDF Black Box,implemented
on .NET, my requirement is to show a visible Signature on a PDF,
which is signed over a web app, your distributed solution does the
same, but, the signature is coming as invisible, i need to show the
signature on a specific location of the PDF, i tried to make the change in signature property, "signature.Invisible = true;"
to false, but getting error "No signing certificate found".
Posted: 09/06/2012 02:41:17
by Vsevolod Ievgiienko (EldoS Corp.)

Thank you for contacting us.

Please refer to our sample from \EldoS\SecureBlackbox.NET\Samples\C#\PDFBlackbox\Signer folder. It shows how to create visible signatures.
Posted: 09/12/2012 03:33:17
by Vineet Luthra (Basic support level)
Joined: 09/06/2012
Posts: 3

I followed the sample in the Signer folder, still facing the same problem, because in the Signer sample ur explicitly selecting Certificate Storage and the Certificate before Signing for Visible Signature, but in your distributed sample which is web based and using Activex control, it gives me the option to select certificate only after loading the PreSigner Page.

For the distributed sample
When i am using "signature.Invisible = true;", then it does not ask for any certificate at PreSigner stage, but when i do "signature.Invisible = false;" , then it ask for a Certificate, which we have still not selected.

Hence not able to go forward, with visible signature, please suggest the way out to this problem.
Posted: 09/12/2012 04:56:00
by Ken Ivanov (EldoS Corp.)


When creating a visible signature under the default configuration, PDFBlackbox automatically tries to fill widget text fields (header, signer and algorithm details) with information contained in the signing certificate. As the signing certificate is not yet known on the pre-signing stage, the security handler fails to obtain this information and throws an exception.

This way, to be able to create visible signatures in distributed way, you should provide the widget texts from your code so that the handler knew what to draw on the widget. To do this, please set TElPDFSignature.WidgetProps.AutoText property to false and assign appropriate text lines to TElPDFSignature.WidgetProps.Header, .SignerInfo and .AlgorithmInfo properties.
Posted: 09/13/2012 01:40:29
by Vineet Luthra (Basic support level)
Joined: 09/06/2012
Posts: 3

Hi Innokentiy, thanx for your response.

I tried to follow the advise which you have given, but still unable to Sign, may be i am doing something wrong, it will be very grateful if you can send me a working example for distributed signing with Visible Signature on a specific PDF coordinates. My mail id - vlut888@its.jnj.com
Posted: 09/13/2012 02:09:08
by Eugene Mayevski (EldoS Corp.)

What exactly did you do (please show the code snippet) and what "was unable" meant in your case?

Sincerely yours
Eugene Mayevski
Also by EldoS: Solid File System
A virtual file system that offers a feature-rich storage for application documents and data with built-in compression and encryption.



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