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How do I detect that a PDF has a digital signature
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AnnD View Drop Down
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Joined: 30 Jan 13
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Points: 3 		Post Options Post Options   Thanks (0) Thanks(0)   Quote AnnD Quote  Post ReplyReply Direct Link To This Post Topic: How do I detect that a PDF has a digital signature
    Posted: 11 Feb 13 at 9:28PM
In my application I am adding some modifications to a PDF file.  I don't want to invalidate the digital signature, so I want to skip the modification if a file has a digital signature.  How do I determine if the file has a digital signature using the QuickPDF api?
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Ingo View Drop Down
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Joined: 29 Oct 05
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Points: 3530 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Ingo Quote  Post ReplyReply Direct Link To This Post Posted: 12 Feb 13 at 10:14AM
Hi Ann!
 
That's not possible with QuickPDF-functionality:
What i can imagine is ...
Read the complete pdf-content into a string and check for
special tags having to do with signatures.
Before you should have a look (with notepad) into a pdf
without and with signature to see the differences.
Only an idea ... perhaps it works ;-)
 
Cheers and welcome here,
Ingo
 
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AndrewC View Drop Down
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Points: 841 		Post Options Post Options   Thanks (0) Thanks(0)   Quote AndrewC Quote  Post ReplyReply Direct Link To This Post Posted: 18 Feb 13 at 7:10AM

You may want to try the following code

            bool hasSig = false;
            for (int i = 1; i <= QP.FormFieldCount(); i++)
                if (QP.GetFormFieldType(i) == 6)     // FormFieldType = Signature
                    hasSig = true;
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Ingo View Drop Down
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Joined: 29 Oct 05
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Points: 3530 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Ingo Quote  Post ReplyReply Direct Link To This Post Posted: 18 Feb 13 at 1:41PM
Good to know.
Should be something for the guides or samples?
Nobody will have the idea to check the formfield-types ;-)
 
Cheers, Ingo
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