PdfDeferredSigner Class

Allows you to sign the document hash.

Namespace: DevExpress.Pdf

Assembly: DevExpress.Docs.v25.1.dll

NuGet Package: DevExpress.Document.Processor

Declaration

C#

public class PdfDeferredSigner

VB.NET

Public Class PdfDeferredSigner

Related API Members

The following members return PdfDeferredSigner objects:

• PdfDocumentSigner.SignDeferred(PdfDeferredSignatureBuilder)

Remarks

The PdfDeferredSigner.Sign method writes the signature contents to the document and saves the signed document to the file or stream. Use the ITsaClient.GenerateTimeStamp(Byte[], String) or IExternalSigner.BuildSignature(Byte[], String) method to obtain the signature contents.

The code sample below uses a document hash to apply a signature externally:

C#

using DevExpress.Office.DigitalSignatures;
using DevExpress.Pdf;

using (var signer = new PdfDocumentSigner(File.OpenRead("SignDemo.pdf")))
{
  // Specify the information about the signature metadata:
  var digestCalculator = new DigestCalculator(HashAlgorithmType.SHA256);

  var signerInfo = new ExternalSignerInfo(PdfSignatureType.Pkcs7, 8000, digestCalculator);

  // Create a new form field:
  var fieldInfo = new PdfSignatureFieldInfo(1) { SignatureBounds = new PdfRectangle(10, 10, 100, 100) };

  // Apply the metadata to the form field:
  var builder = new PdfDeferredSignatureBuilder(signerInfo, fieldInfo);

  // Add the signature to the document:
  var deferredSigner = signer.SignDeferred(builder);

  // Obtain the document hash and hash algorithm's object identifier:
  var digest = deferredSigner.HashValue;
  var digestAlgorithmOID = digestCalculator.AlgorithmOid;

  // Generate the signature content to insert into the document:
  byte[] signature = CreateSignature(digest, digestAlgorithmOID);

  // Add the signature contents and save the document to the file:
  deferredSigner.Sign("signed.pdf", signature);
}

static byte[] CreateSignature(byte[] digest, string digestAlgorithmOID)
{
  var signer = new Pkcs7Signer(@"SignDemo.pfx", "dxdemo");
  byte[] signature = signer.BuildSignature(digest, digestAlgorithmOID);
  return signature;
}

VB.NET

Imports DevExpress.Office.DigitalSignatures
Imports DevExpress.Pdf

Using signer = New PdfDocumentSigner(File.OpenRead("SignDemo.pdf"))
  ' Specify the information about the signature metadata:
  Dim digestCalculator = New DigestCalculator(HashAlgorithmType.SHA256)

  Dim signerInfo = New ExternalSignerInfo(PdfSignatureType.Pkcs7, 8000, digestCalculator)

  ' Create a new form field:
  Dim fieldInfo = New PdfSignatureFieldInfo(1) With {.SignatureBounds = New PdfRectangle(10, 10, 100, 100)}

  ' Apply the metadata to the form field:
  Dim builder = New PdfDeferredSignatureBuilder(signerInfo, fieldInfo)

  ' Add the signature to the document:
  Dim deferredSigner = signer.SignDeferred(builder)

  ' Obtain the document hash and hash algorithm's object identifier:
  Dim digest = deferredSigner.HashValue
  Dim digestAlgorithmOID = digestCalculator.AlgorithmOid

  ' Generate the signature content to insert into the document:
  Dim signature() As Byte = CreateSignature(digest, digestAlgorithmOID)

  ' Add the signature contents and save the document to the file:
  deferredSigner.Sign("signed.pdf", signature)
End Using

Private Function CreateSignature(ByVal digest As Byte(), ByVal digestAlgorithmOID As String) As Byte()
    Dim signer = New Pkcs7Signer("SignDemo.pfx", "dxdemo")
    Dim signature As Byte() = signer.BuildSignature(digest, digestAlgorithmOID)
    Return signature
End Function

Inheritance

Object

PdfDeferredSigner