如何在C#中的现有PDF文件中添加数字戳记？

我有一个PDF文件，需要在文件的特定位置加盖数字印章。我把印章放在文件中，但我想把印章放在文件的特定位置

这是我的密码

protected void btnCreatePDF_Click(object sender, EventArgs e)
{
    String cert = "C:/Users/arehman.SHERPC-1009/Desktop/New folder (3)/iTextSharpSign_TemporaryKey.pfx";
    PdfFileSignature pdfSign = new PdfFileSignature();
    pdfSign.BindPdf("C:/Users/arehman.SHERPC-1009/Downloads/FormalUndertakingForm (5).pdf");
    //create a rectangle for signature location
    System.Drawing.Rectangle rect = new System.Drawing.Rectangle(50, 50, 100, 50);
    //set signature appearance
    pdfSign.SignatureAppearance = "c:/users/arehman.sherpc-1009/documents/visual studio 2010/Projects/TestApp/TestApp/Images/sig55.png";
    //create any of the three signature types
    PKCS1 signature = new PKCS1(cert, "edge123"); // PKCS#1 or
    signature.ShowProperties = false;
    //PKCS7 signature = new PKCS7("test.pfx", "password"); // PKCS#7 or
    //PKCS7Detached signature = new PKCS7Detached("test.pfx", "password"); // PKCS#7 detached
    pdfSign.Sign(2, true, rect, signature);

    //save output PDF file
    pdfSign.Save("C:/Users/arehman.SHERPC-1009/Downloads/Pdf/output.pdf");            
}

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您使用的类的名称（特别是

PdfFileSignature

）不是iTextSharp类。您使用的类的名称（特别是

PdfFileSignature

）不是iTextSharp类。