SignedXml.AddObject(DataObject) Method

Definition

Adds a DataObject object to the list of objects to be signed.

public:
 void AddObject(System::Security::Cryptography::Xml::DataObject ^ dataObject);
public void AddObject (System.Security.Cryptography.Xml.DataObject dataObject);
member this.AddObject : System.Security.Cryptography.Xml.DataObject -> unit
Public Sub AddObject (dataObject As DataObject)

Parameters

dataObject
DataObject

The DataObject object to add to the list of objects to be signed.

Examples

The following code example computes and XML signature.

// This example signs an XML file using an
// envelope signature. It then verifies the 
// signed XML.
#using <System.Security.dll>
#using <System.Xml.dll>

using namespace System;
using namespace System::Security::Cryptography;
using namespace System::Security::Cryptography::Xml;
using namespace System::Text;
using namespace System::Xml;

// Sign an XML file and save the signature in a new file.
void SignXmlFile( String^ FileName, String^ SignedFileName, RSA^ RSAKey )
{
   
   // Create a new XML document.
   XmlDocument^ doc = gcnew XmlDocument;
   
   // Format the document to ignore white spaces.
   doc->PreserveWhitespace = false;
   
   // Load the passed XML file using its name.
   doc->Load( gcnew XmlTextReader( FileName ) );
   
   // Create a SignedXml object.
   SignedXml^ signedXml = gcnew SignedXml( doc );
   
   // Add the RSA key to the SignedXml document. 
   signedXml->SigningKey = RSAKey;
   
   // Create a reference to be signed.
   Reference^ reference = gcnew Reference;
   reference->Uri = "";
   
   // Add a transformation to the reference.
   Transform^ trns = gcnew XmlDsigC14NTransform;
   reference->AddTransform( trns );
   
   // Add an enveloped transformation to the reference.
   XmlDsigEnvelopedSignatureTransform^ env = gcnew XmlDsigEnvelopedSignatureTransform;
   reference->AddTransform( env );
   
   // Add the reference to the SignedXml object.
   signedXml->AddReference( reference );
   
   // Add an RSAKeyValue to the KeyInfo (optional; helps recipient find key to validate).
   KeyInfo^ keyInfo = gcnew KeyInfo;
   keyInfo->AddClause( gcnew RSAKeyValue( safe_cast<RSA^>(RSAKey) ) );
   signedXml->KeyInfo = keyInfo;
   
   // Compute the signature.
   signedXml->ComputeSignature();
   
   // Get the XML representation of the signature and save
   // it to an XmlElement object.
   XmlElement^ xmlDigitalSignature = signedXml->GetXml();
   
   // Append the element to the XML document.
   doc->DocumentElement->AppendChild( doc->ImportNode( xmlDigitalSignature, true ) );
   if ( (doc->FirstChild)->GetType() == XmlDeclaration::typeid )
   {
      doc->RemoveChild( doc->FirstChild );
   }

   
   // Save the signed XML document to a file specified
   // using the passed string.
   XmlTextWriter^ xmltw = gcnew XmlTextWriter( SignedFileName,gcnew UTF8Encoding( false ) );
   doc->WriteTo( xmltw );
   xmltw->Close();
}


// Verify the signature of an XML file and return the result.
Boolean VerifyXmlFile( String^ Name )
{
   
   // Create a new XML document.
   XmlDocument^ xmlDocument = gcnew XmlDocument;
   
   // Format using white spaces.
   xmlDocument->PreserveWhitespace = true;
   
   // Load the passed XML file into the document. 
   xmlDocument->Load( Name );
   
   // Create a new SignedXml object and pass it
   // the XML document class.
   SignedXml^ signedXml = gcnew SignedXml( xmlDocument );
   
   // Find the "Signature" node and create a new
   // XmlNodeList object.
   XmlNodeList^ nodeList = xmlDocument->GetElementsByTagName( "Signature" );
   
   // Load the signature node.
   signedXml->LoadXml( safe_cast<XmlElement^>(nodeList->Item( 0 )) );
   
   // Check the signature and return the result.
   return signedXml->CheckSignature();
}


// Create example data to sign.
void CreateSomeXml( String^ FileName )
{
   
   // Create a new XmlDocument object.
   XmlDocument^ document = gcnew XmlDocument;
   
   // Create a new XmlNode object.
   XmlNode^ node = document->CreateNode( XmlNodeType::Element, "", "MyElement", "samples" );
   
   // Add some text to the node.
   node->InnerText = "Example text to be signed.";
   
   // Append the node to the document.
   document->AppendChild( node );
   
   // Save the XML document to the file name specified.
   XmlTextWriter^ xmltw = gcnew XmlTextWriter( FileName,gcnew UTF8Encoding( false ) );
   document->WriteTo( xmltw );
   xmltw->Close();
}

int main()
{
   try
   {
      
      // Generate an RSA signing key.
      RSA^ RSAKey = RSA::Create();
      
      // Create an XML file to sign.
      CreateSomeXml( "Example.xml" );
      Console::WriteLine( "New XML file created." );
      
      // Sign the XML that was just created and save it in a 
      // new file.
      SignXmlFile( "Example.xml", "SignedExample.xml", RSAKey );
      Console::WriteLine( "XML file signed." );
      
      // Verify the signature of the signed XML.
      Console::WriteLine( "Verifying signature..." );
      bool result = VerifyXmlFile( "SignedExample.xml" );
      
      // Display the results of the signature verification to
      // the console.
      if ( result )
      {
         Console::WriteLine( "The XML signature is valid." );
      }
      else
      {
         Console::WriteLine( "The XML signature is not valid." );
      }
   }
   catch ( CryptographicException^ e ) 
   {
      Console::WriteLine( e->Message );
   }

}

using System;
using System.IO;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
using System.Xml;

public class XMLdsigsample1 
{

    static void Main(String[] args)
    {
        try
        {
            // Create example data to sign.
            XmlDocument document = new XmlDocument();
            XmlNode node = document.CreateNode(XmlNodeType.Element, "", "MyElement", "samples");
            node.InnerText = "This is some text";
            document.AppendChild(node);
            Console.WriteLine("Data to sign:\n" + document.OuterXml + "\n");
 
            // Create the SignedXml message.
            SignedXml signedXml = new SignedXml();
            RSA key = RSA.Create();
            signedXml.SigningKey = key;
 
            // Create a data object to hold the data to sign.
            DataObject dataObject = new DataObject();
            dataObject.Data = document.ChildNodes;
            dataObject.Id = "MyObjectId";

            // Add the data object to the signature.
            signedXml.AddObject(dataObject);
 
            // Create a reference to be able to package everything into the
            // message.
            Reference reference = new Reference();
            reference.Uri = "#MyObjectId";
 
            // Add the reference to the message.
            signedXml.AddReference(reference);

            // Add a KeyInfo.
            KeyInfo keyInfo = new KeyInfo();
            keyInfo.AddClause(new RSAKeyValue(key));
            signedXml.KeyInfo = keyInfo;

            // Compute the signature.
            signedXml.ComputeSignature();

            Console.WriteLine("The data was signed.");
        }
        catch(CryptographicException e)
        {
            Console.WriteLine(e.Message);
        }
    }
}
Imports System.IO
Imports System.Security.Cryptography
Imports System.Security.Cryptography.Xml
Imports System.Xml




Public Class XMLdsigsample1
   
   
   Overloads Shared Sub Main(args() As [String])
      Try
         ' Create example data to sign.
         Dim document As New XmlDocument()
         Dim node As XmlNode = document.CreateNode(XmlNodeType.Element, "", "MyElement", "samples")
         node.InnerText = "This is some text"
         document.AppendChild(node)
         Console.WriteLine(("Data to sign:" + ControlChars.Lf + document.OuterXml + ControlChars.Lf))
         
         ' Create the SignedXml message.
         Dim signedXml As New SignedXml()
         Dim key As RSA = RSA.Create()
         signedXml.SigningKey = key
         
         ' Create a data object to hold the data to sign.
         Dim dataObject As New DataObject()
         dataObject.Data = document.ChildNodes
         dataObject.Id = "MyObjectId"
         
         ' Add the data object to the signature.
         signedXml.AddObject(dataObject)
         
         ' Create a reference to be able to package everything into the
         ' message.
         Dim reference As New Reference()
         reference.Uri = "#MyObjectId"
         
         ' Add the reference to the message.
         signedXml.AddReference(reference)
         
         ' Add a KeyInfo.
         Dim keyInfo As New KeyInfo()
         keyInfo.AddClause(New RSAKeyValue(key))
         signedXml.KeyInfo = keyInfo
         
         ' Compute the signature.
         signedXml.ComputeSignature()
         
         Console.WriteLine("The data was signed.")
      Catch e As CryptographicException
         Console.WriteLine(e.Message)
      End Try
   End Sub 
End Class 

Remarks

The AddObject method adds an <Object> element that represents an object to be signed to the <Signature> element of an XML digital signature.

The AddObject method internally calls the AddObject method of the Signature object encapsulated by the SignedXml object. You can also add a DataObject object by directly calling the AddObject method from the Signature property.

For more information about XML digital signatures, see the XMLDSIG specification.

Applies to