How to: Sign a PDF File with a Certificate Stored in a .PFX File

• Jul 11, 2025
• 3 minutes to read

The PdfDocumentSigner class allows you to sign and save documents with signatures (PKCS#7) and certificates (X.509). For example, you can use certificates stored in a .PFX file. To apply a signature to a form field in these documents, use the PdfSignatureBuilder class.

The following code snippet executes the following actions:

• Creates a PKCS#7 signature with a certificate stored in a .PFX file,
• Applies a digital signature to a new and existing form field,
• Signs a document with these signatures.

View Example: How to Apply Multiple Signatures

C#

using System;
using DevExpress.Pdf;
using System.Diagnostics;
using System.IO;
using DevExpress.Office.DigitalSignatures;

// Load a document to sign:
using (var signer = new PdfDocumentSigner("Document.pdf"))
{

    // Specify the name and location of the signature field
    var signatureFieldInfo = new PdfSignatureFieldInfo(1);
    signatureFieldInfo.Name = "SignatureField";
    signatureFieldInfo.SignatureBounds = new PdfRectangle(20, 20, 150, 150);
    signatureFieldInfo.RotationAngle = PdfAcroFormFieldRotation.Rotate90;

    // Create a PKCS#7 signature:
    Pkcs7Signer pkcs7Signature = new Pkcs7Signer("Signing Documents/certificate.pfx", "123", 
        HashAlgorithmType.SHA256);

    // Apply a signature to a newly created signature field:
    var cooperSignature = new PdfSignatureBuilder(pkcs7Signature, signatureFieldInfo);

    // Specify an image and signer information:
    cooperSignature.SetImageData(File.ReadAllBytes("Signing Documents//JaneCooper.jpg"));
    cooperSignature.Location = "USA";
    cooperSignature.Name = "Jane Cooper";
    cooperSignature.Reason = "Acknowledgement";

    // Apply a signature to an existing form field:
    var santuzzaSignature = new PdfSignatureBuilder(pkcs7Signature, "Sign");

    // Specify an image and signer information:
    santuzzaSignature.SetImageData(File.ReadAllBytes("Signing Documents//SantuzzaValentina.jpg"));
    santuzzaSignature.Location = "Australia";
    santuzzaSignature.Name = "Santuzza Valentina";
    santuzzaSignature.Reason = "I Agree";

    // Add signatures to an array:
    PdfSignatureBuilder[] signatures = { cooperSignature, santuzzaSignature };

    // Sign and save the document:
    signer.SaveDocument("SignedDocument.pdf", signatures);
}

VB.NET

Imports System
Imports DevExpress.Pdf
Imports System.Diagnostics
Imports System.IO
Imports DevExpress.Office.DigitalSignatures

' Load a document to sign:
Using signer = New PdfDocumentSigner("Document.pdf")

  'Specify the name and location of the signature field
  Dim signatureFieldInfo = New PdfSignatureFieldInfo(1)
  signatureFieldInfo.Name = "SignatureField"
  signatureFieldInfo.SignatureBounds = New PdfRectangle(20, 20, 150, 150)
  signatureFieldInfo.RotationAngle = PdfAcroFormFieldRotation.Rotate90

  ' Create a PKCS#7 signature:
  Dim pkcs7Signature As New Pkcs7Signer("Signing Documents/certificate.pfx", "123", 
                                        HashAlgorithmType.SHA256)

  ' Apply a signature to a newly created signature field:
  Dim cooperSignature = 
    New PdfSignatureBuilder(pkcs7Signature, signatureFieldInfo)

  ' Specify an image and signer information:
  cooperSignature.SetImageData(File.ReadAllBytes("Signing Documents//JaneCooper.jpg"))
  cooperSignature.Location = "USA"
  cooperSignature.Name = "Jane Cooper"
  cooperSignature.Reason = "Acknowledgement"

  ' Apply a signature to an existing form field:
  Dim santuzzaSignature = New PdfSignatureBuilder(pkcs7Signature, "Sign")

  ' Specify an image and signer information:
  santuzzaSignature.SetImageData(File.ReadAllBytes("Signing Documents//SantuzzaValentina.jpg"))
  santuzzaSignature.Location = "Australia"
  santuzzaSignature.Name = "Santuzza Valentina"
  santuzzaSignature.Reason = "I Agree"

  ' Add signatures to an array:
  Dim signatures() As PdfSignatureBuilder = { cooperSignature, santuzzaSignature }

  ' Sign and save the document:
  signer.SaveDocument("SignedDocument.pdf", signatures)
End Using