Digital signature is more advanced and more popular to detect forgery and tampering today compared with traditional handwritten signature. Especially in business world, digital signature becomes an effective method to safeguard and authenticate your documents. As long as a digital signature is created and singed, the document has not been tampered and the recipients can view both the document version history and any changes that were made to it. Now, it is time to see how to create a PDF digital signature via a WPF PDF component Spire.PDF for WPF.

Spire.PDF for WPF, as a PDF component, enables you to create PDF digital signature in a simple way which can not only ensure your data information has not been altered since it was sent but also verify the signer's digital identity. The key procedure only requires six lines of code. Please preview the effective screenshot below, and then, view the key code.

Please feel free to Download Spire.PDF for WPF first before the key code below. In this solution, for constructing one instance of a Spire.Pdf.Sercurity.PdfCertificate class named cert, we reference a certificate file and its file protect password as parameters. Then, cert is applied to create an instance of a PdfSignature class we name it signature. Setting signature “page” parameter allows you to sign the digital signature of any PDF page. And DocumentPermissions, one property of signature, can be set: AllowComments, AllowFormFill and ForbidChanges.

Core Code:

String pfxPath = @"..\Data\Demo.pfx";
PdfCertificate cert = new PdfCertificate(pfxPath, "e-iceblue");
PdfSignature signature = new PdfSignature(doc, page, cert, "demo");
signature.ContactInfo = "Harry Hu";
signature.Certificated = true;
signature.DocumentPermissions = PdfCertificationFlags.AllowFormFill;

Dim pfxPath As String = "..\Data\Demo.pfx"
Dim cert As New PdfCertificate(pfxPath, "e-iceblue")
Dim signature As New PdfSignature(doc, page, cert, "demo")
signature.ContactInfo = "Harry Hu"
signature.Certificated = True
signature.DocumentPermissions = PdfCertificationFlags.AllowFormFill