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Digital Signatures and PDF

I have a question regarding the features I’m looking for. We have two scenarios:

1) Checking for existing digital signatures:

A PDF document is uploaded to our solution (it’s a server side solution)
We then have to check if it has a digital signature or not
If it has a digital signature, we have to validate the signature and extract basic info (name etc.) regarding the person who own the signature

2) Adding signatures to a new PDF document:

The user select a PDF file for signing
The users existing X509-based certificate is used (the user is queried for a password to use the signature)
The document is signed

Hi Lector,

First thank you for considering aspose product. now aspose.pdf.kit support signaturing a pdf document with X509-based certificate. you can refer to the class PdfFileSignature.cs.the example code is as below.

string inFile=TestPath + "example1.pdf";
string outFile=TestPath + "signature.pdf";
Certificate cert=new Certificate(TestPath+"allen.pfx","psw");
PdfFileSignature pdfSign=new PdfFileSignature(cert);
System.Drawing.Rectangle rect=new System.Drawing.Rectangle(100,100, 200, 100);

But the kit does not support the the feature about Checking for existing digital signatures. we will investigate the feature and plan to support the feature . When this feature is supported, I will inform you.