DigestCalculator(HashAlgorithmType) Constructor

SECURITY-RELATED CONSIDERATIONS

Using weak or outdated hash algorithms (such as SHA-1) may allow threat actors to manipulate or predict hash values. Use modern, secure alternatives (such as SHA-256 or stronger).

Initializes a new instance of the DigestCalculator class with specified settings.

Namespace: DevExpress.Office.DigitalSignatures

Assembly: DevExpress.Pdf.v25.2.Core.dll

NuGet Package: DevExpress.Pdf.Core

Declaration

C#

public DigestCalculator(
    HashAlgorithmType algorithm
)

VB.NET

Public Sub New(
    algorithm As HashAlgorithmType
)

Parameters

Name	Type	Description
algorithm	HashAlgorithmType	The hashing algorithm.

Example

The code sample below shows how to retrieve signed form field names and apply a new signature to the first field:

C#

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

    // Retrieve all signed form fields:
    var signedFields = signer.GetSignatureFieldNames(false);

    // Clear the first signature field:
    signer.ClearSignatureField(signedFields[0]);

    // Apply a new signature to this form field:
    var santuzzaSignature = new PdfSignatureBuilder(pkcs7Signature, signedFields[0]);

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

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

VB.NET

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

' Load a document to sign:
Using signer = New PdfDocumentSigner("Document.pdf")
  ' Create a PKCS#7 signature:
  Dim pkcs7Signature As New Pkcs7Signer("Signing Documents//certificate.pfx", "123", 
                                        HashAlgorithmType.SHA256)

  ' Retrieve all signed form fields:
  Dim signedFields = signer.GetSignatureFieldNames(False)

  ' Clear the first signature field:
  signer.ClearSignatureField(signedFields(0))

  ' Apply a new signature to this form field:
  Dim santuzzaSignature = New PdfSignatureBuilder(pkcs7Signature, signedFields(0))

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

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