How to Remove Digital Signature From Existing WinForms PDF Using C#?
Syncfusion Essential® PDF is a .NET PDF library used to create, read, and edit PDF documents. Using this library, you can remove the digital signature from an existing PDF using C# and VB.NET.
Steps to remove digital signature from an existing PDF programmatically:
- Create a new C# console application project.
- Install the Syncfusion.Pdf.WinForms NuGet package as a reference to your .NET Framework application from NuGet.org.
- Include the following namespaces in the Program.cs file.
C#
using Syncfusion.Pdf.Parsing;
VB.NET
Imports Syncfusion.Pdf.Parsing
- Use the following code snippet to remove the digital signature from an existing PDF document.
C#
// Loads an existing PDF document
PdfLoadedDocument loadedDocument = new PdfLoadedDocument("DigitallySigned.pdf");
// Get the signature field from PdfLoadedDocument form field collection
PdfLoadedSignatureField signatureField = loadedDocument.Form.Fields[0] as PdfLoadedSignatureField;
// Remove signature field from PdfLoadedDocument form field collection
loadedDocument.Form.Fields.Remove(signatureField);
// Save the document
loadedDocument.Save("DigitalSignatureRemoved.pdf");
// Close the document
loadedDocument.Close(true);
// This will open the PDF file so the result will be seen in the default PDF Viewer
Process.Start("DigitalSignatureRemoved.pdf");VB.NET
'Loads an existing PDF document
Dim loadedDocument As New PdfLoadedDocument("DigitallySigned.pdf")
'Get the signature field from PdfLoadedDocument form field collection
Dim signatureField As PdfLoadedSignatureField = TryCast(loadedDocument.Form.Fields(0), PdfLoadedSignatureField)
'Remove signature field from PdfLoadedDocument form field collection
loadedDocument.Form.Fields.Remove(signatureField)
'Save the document
loadedDocument.Save("DigitalSignatureRemoved.pdf")
'Close the document
loadedDocument.Close(True)
'This will open the PDF file so the result will be seen in the default PDF Viewer
Process.Start("DigitalSignatureRemoved.pdf")A complete working sample can be downloaded from DigitalSignatureRemovalSample.zip.
By executing the program, you will get the PDF document as follows. 
Take a moment to peruse the documentation for using digital signatures in PDF, where you will find other options like support for adding a digital signature to a PDF, signing an existing document, and also validateing the signature appearance based on the signature. You can also add the signature field to a PDF document.
An online sample link demonstrates how to sign a PDF document using a digital signature.
Refer here to explore the rich set of Syncfusion Essential® PDF features.
Starting with v16.2.0.x, if you reference Syncfusion® assemblies from the trial setup or the NuGet feed, include a license key in your projects. Refer to the link to learn about generating and registering the Syncfusion® license key in your application to use the components without a trial message.
Conclusion
I hope you enjoyed learning about how to remove a digital signature from an existing WinForms PDF using C#.
You can refer to our .NET PDF library page to know about its other groundbreaking feature representations and documentation, and how to quickly get started for configuration specifications. You can also explore our .NET PDF Library examples to understand how to create and manipulate data.
For current customers, you can check out our components from the License and Downloads page. If you are new to Syncfusion, you can try our 30-day free trial to check out our other controls.
If you have any queries or require clarifications, please let us know in the comments section below. You can also contact us through our support forums or feedback portal. We are always happy to assist you!
