officefileapi-devexpress-dot-pdf-1a929d5e.md
Allows you to sign the document hash.
Namespace : DevExpress.Pdf
Assembly : DevExpress.Docs.v25.2.dll
NuGet Package : DevExpress.Document.Processor
public class PdfDeferredSigner
Public Class PdfDeferredSigner
The following members return PdfDeferredSigner objects:
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:
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;
}
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
Object PdfDeferredSigner
See Also