Multiple Digital Signing with PdfStreamSigner
As of Q2 2025 RadPdfProcessing introduces the PdfStreamSigner. The SignDocument method it exposes allows the user to insert one or more Digital Signatures into a PDF document.
When adding multiple signatures, make sure the document is exported after each signature before importing it back again.
| Method | Description |
|---|---|
| PdfStreamSigner(Stream outputStream) | Creates a new instance of thе PdfStreamSigner and specifies the output stream of the signed document. |
| SignDocument(Stream originalStream, SignatureField signatureField, int pageIndex, TimeSpan? timeout) | Adds a Digital Signature to the PDF document |
The following example shows how to insert multiple Digital Signatures into a PDF document using the PdfStreamSigner:
In .NET Standard use Telerik.Documents.Primitives.Rect instead of System.Windows.Rect.
public void AddMultipleDigitalSignatures()
{
string certificateFilePath = "certificate.pfx";
string certificateFilePassword = "password";
// Define the certificate which will be used for the signing.
X509Certificate2 certificate = new X509Certificate2(certificateFilePath, certificateFilePassword);
// Create the first signature field.
SignatureField signature1Field = this.CreateSignatureField(
"SampleSignature1",
certificate,
new Point(50, 50),
20,
new Rect(200, 200, 100, 100)
);
string inputDocument = "input.pdf";
string oneSignatureDocument = "oneSignatureDocument.pdf";
File.Delete(oneSignatureDocument);
using (FileStream inputStream = File.OpenRead(inputDocument))
{
using (FileStream outputStream = new FileStream(oneSignatureDocument, FileMode.OpenOrCreate))
{
PdfStreamSigner signer = new PdfStreamSigner(outputStream);
signer.SignDocument(inputStream, signature1Field, pageIndex: 0, timeout: null);
}
}
// Create the second signature field.
SignatureField signature2Field = this.CreateSignatureField(
"SampleSignature2",
certificate,
new Point(50, 50),
20,
new Rect(500, 200, 100, 100)
);
string twoSignatureDocument = "twoSignatureDocument.pdf";
using (FileStream inputStream = File.OpenRead(oneSignatureDocument))
{
using (FileStream outputStream = new FileStream(twoSignatureDocument, FileMode.OpenOrCreate))
{
PdfStreamSigner signer = new PdfStreamSigner(outputStream);
signer.SignDocument(inputStream, signature2Field, pageIndex: 0, timeout: null);
}
}
}
private SignatureField CreateSignatureField(string signatureName, X509Certificate2 certificate, Point circleCenter, double circleRadius, Rect widgetRect)
{
// This is the Form XObject element that represents the contents of the signature field.
Form signatureForm = new Form();
signatureForm.FormSource = new FormSource();
signatureForm.FormSource.Size = new Size(120, 120);
// We will use the editor to fill the Form XObject.
FixedContentEditor formEditor = new FixedContentEditor(signatureForm.FormSource);
formEditor.DrawCircle(circleCenter, circleRadius);
formEditor.DrawText(signatureName);
// The Signature object is added to a signature field, so we can add a visualization to it.
SignatureField signatureField = new SignatureField(signatureName);
signatureField.Signature = new Telerik.Windows.Documents.Fixed.Model.DigitalSignatures.Signature(certificate);
// The widget contains the Form XObject and defines the appearance of the signature field.
SignatureWidget signatureWidget = signatureField.Widgets.AddWidget();
signatureWidget.Rect = widgetRect;
signatureWidget.Border = new AnnotationBorder(100, AnnotationBorderStyle.Solid, null);
signatureWidget.Content.NormalContentSource = signatureForm.FormSource;
return signatureField;
}
