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PdfTimeStamp.BuildSignature(Byte[], String) Method

Builds the signature and returns its contents.

Namespace: DevExpress.Pdf

Assembly: DevExpress.Pdf.v23.2.Core.dll

NuGet Package: DevExpress.Pdf.Core


public byte[] BuildSignature(
    byte[] digest,
    string digestAlgorithmOID


Name Type Description
digest Byte[]

The document’s hash value.

digestAlgorithmOID String

The hash algorithm’s object identifier.


Type Description

The signature contents.


Utilize this method overload to obtain the signature contents used in the PdfDeferredSigner.Sign method.

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;
See Also