PDF: How to remove digital signature from PDF document

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If digital gignature should be removed from PDF document, the following steps must be done:

Find the field that stores the digital signature
Remove the field from interactive form of PDF document
Save the PDF document

Here is C#/VB.NET code that demonstrates how to remove all digital signatures from PDF document:

using Vintasoft.Imaging.Pdf;
using Vintasoft.Imaging.Pdf.Tree.InteractiveForms;

public class PdfSignaturesHelper2
{
    /// <summary>
    /// Removes all digital signatures from PDF document.
    /// </summary>
    /// <param name="pdfFilename">The filename of PDF document.</param>
    public static void RemoveDigitalSignaturesFromPdfDocument(string pdfFilename)
    {
        // open PDF document
        using (PdfDocument document = new PdfDocument(pdfFilename))
        {
            // if PDF document has PDF interactive form
            if (document.InteractiveForm != null)
            {
                // for each signature field
                foreach (PdfInteractiveFormField field in
                    document.InteractiveForm.GetSignatureFields())
                {
                    // remove signature field
                    field.Remove();
                }

                // pack PDF document
                document.Pack();
            }
        }
    }
}

VB.NET

Imports Vintasoft.Imaging.Pdf
Imports Vintasoft.Imaging.Pdf.Tree.InteractiveForms

Public Class PdfSignaturesHelper2
    ''' <summary>
    ''' Removes all digital signatures from PDF document.
    ''' </summary>
    ''' <param name="pdfFilename">The filename of PDF document.</param>
    Public Shared Sub RemoveDigitalSignaturesFromPdfDocument(pdfFilename As String)
        ' open PDF document
        Using document As New PdfDocument(pdfFilename)
            ' if PDF document has PDF interactive form
            If document.InteractiveForm IsNot Nothing Then
                ' for each signature field
                For Each field As PdfInteractiveFormField In document.InteractiveForm.GetSignatureFields()
                    ' remove signature field
                    field.Remove()
                Next

                ' pack PDF document
                document.Pack()
            End If
        End Using
    End Sub
End Class

Please read how to add digital signature to a PDF document here.
Please read how to verify the digital signatures in PDF document here.

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