How To: Use PdfDocumentProcessor to Add a Visual Signature to a Document

Feb 04, 2025
4 minutes to read

Important

You need a license for the DevExpress Office File API Subscription or DevExpress Universal Subscription to use these examples in production code.

The PdfDocumentProcessor allows you to apply a signature with the CMS/PKCS #7 message and adbe.pkcs7.detached signature value encoding.

Note that you can sign a document only once. Use the PdfDocumentSigner and PdfSignatureBuilder classes to apply multiple signatures. Refer to the following article for more information: Sign Documents

Important

The PdfDocumentProcessor removes existing signatures from a document when it is saved. However, if you use PdfDocumentProcessor to apply a signature, it is retained. Use the PdfSignatureBuilder to apply multiple signatures to the document.

Use the API from the table below to create a visual signature and specify the signer information.

Member	Description
PdfSignature	A signature. You can use the X509Certificate2 certificate. Pass the Pkcs7Signer object to the constructor to use the PKCS#7 signature.
PdfSignature.Name	Gets or sets the name of the person or authority signing the document.
PdfSignature.Location	Gets or sets the signing location.
PdfSignature.Reason	Gets or sets the reason for a document signature.
PdfSignature.ContactInfo	Specifies the contact information which helps a recipient to verify the signature provided by the signer.
PdfSignature.SigningTime	Gets the time the document was signed.

The following code snippet creates a signature with the X509 certificate:

View Example

C#
VB.NET

csharp

using System.IO;
using System.Security.Cryptography.X509Certificates;
using DevExpress.Pdf;

// Provide a signature certificate:
X509Certificate2 certificate = new X509Certificate2(@"..\..\SignDemo.pfx", "dxdemo");

// Specify the signature's image data and location parameters:
byte[] imageData = File.ReadAllBytes("..\\..\\Signature.png");
int pageNumber = 1;
int angleInDegrees = 45;
double angleInRadians = angleInDegrees * (Math.PI / 180);
PdfOrientedRectangle signatureBounds = new PdfOrientedRectangle(new PdfPoint(0, 460), 250, 90, angleInRadians);

// Pass all instances created above to the PdfSignature constructor:
PdfSignature signature = new PdfSignature(certificate, imageData, pageNumber, signatureBounds);

// Specify the signing information:
signature.Location = "USA";
signature.ContactInfo = "[email protected]";
signature.Reason = "Approved";

// Save a signed document:
documentProcessor.SaveDocument(@"..\..\SignedDocument.pdf", new PdfSaveOptions()
{ Signature = signature });

Imports System.IO
Imports System.Security.Cryptography.X509Certificates
Imports DevExpress.Pdf

' Provide a signature certificate:
Dim certificate As X509Certificate2 = New X509Certificate2("..\..\SignDemo.pfx", "dxdemo")

' Specify the signature's image data and location parameters:
Dim imageData As Byte() = File.ReadAllBytes("..\..\Signature.png")
Dim pageNumber As Integer = 1
Dim angleInDegrees As Integer = 45
Dim angleInRadians As Double = angleInDegrees * (Math.PI / 180)
Dim signatureBounds As PdfOrientedRectangle = New PdfOrientedRectangle(New PdfPoint(0, 460), 250, 90, angleInRadians)

' Pass all instances created above to the PdfSignature constructor:
Dim signature As PdfSignature = New PdfSignature(certificate, imageData, pageNumber, signatureBounds)

' Specify the signing information:
signature.Location = "USA"
signature.ContactInfo = "[email protected]"
signature.Reason = "Approved"

' Save a signed document:
documentProcessor.SaveDocument("..\..\SignedDocument.pdf", New PdfSaveOptions() With
{ Signature = signature })

The following code snippet uses the Pkcs7Signer object to create a signature:

C#
VB.NET

csharp

using System;
using DevExpress.Pdf;
using System.IO;

using (PdfDocumentProcessor processor = new PdfDocumentProcessor())
{
    processor.LoadDocument("Document.pdf");

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

    // Specify the signature's image data and location parameters:
    byte[] imageData = File.ReadAllBytes("Signing Documents//JohnSmith.jpg");
    int pageNumber = 1;
    int angleInDegrees = 45;
    double angleInRadians = angleInDegrees * (Math.PI / 180);
    PdfOrientedRectangle signatureBounds = new PdfOrientedRectangle(new PdfPoint(0, 460), 250, 90, angleInRadians);

    // Pass all instances created above to the PdfSignature constructor:
    PdfSignature signature = new PdfSignature(pkcs7Signature, imageData, pageNumber, signatureBounds);

    // Specify the signing information:
    signature.Location = "USA";
    signature.ContactInfo = "[email protected]";
    signature.Reason = "Approved";

    // Save a signed document:
    processor.SaveDocument("SignedDocument.pdf", new PdfSaveOptions()
    { Signature = signature });
}

Imports System
Imports DevExpress.Pdf
Imports System.IO

Using processor As New PdfDocumentProcessor()
    processor.LoadDocument("Document.pdf")

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

    ' Specify the signature's image data and location parameters:
    Dim imageData() As Byte = File.ReadAllBytes("Signing Documents//JohnSmith.jpg")
    Dim pageNumber As Integer = 1
    Dim angleInDegrees As Integer = 45
    Dim angleInRadians As Double = angleInDegrees * (Math.PI / 180)
    Dim signatureBounds As New PdfOrientedRectangle(New PdfPoint(0, 460), 250, 90, angleInRadians)

    ' Pass all instances created above to the PdfSignature constructor:
    Dim signature As New PdfSignature(pkcs7Signature, imageData, pageNumber, signatureBounds)

    ' Specify the signing information:
    signature.Location = "USA"
    signature.ContactInfo = "[email protected]"
    signature.Reason = "Approved"

    Save a signed document:
    processor.SaveDocument("SignedDocument.pdf", New PdfSaveOptions() With {.Signature = signature})
End Using