SignedXml.Signature Property

Definition

Namespace:

System.Security.Cryptography.Xml

Assembly:

System.Security.Cryptography.Xml.dll

Source:

SignedXml.cs

Gets the Signature object of the current SignedXml object.

public:
 property System::Security::Cryptography::Xml::Signature ^ Signature { System::Security::Cryptography::Xml::Signature ^ get(); };

public System.Security.Cryptography.Xml.Signature Signature { get; }

member this.Signature : System.Security.Cryptography.Xml.Signature

Public ReadOnly Property Signature As Signature

Property Value

Signature

The Signature object of the current SignedXml object.

Examples

The following code example uses the Signature property to sign and verify an entire XML document using an enveloped signature.

//
// This example signs an XML file using an
// envelope signature. It then verifies the 
// signed XML.
//
#using <System.Xml.dll>
#using <System.Security.dll>
#using <System.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.
static void SignXmlFile( String^ FileName, String^ SignedFileName, RSA^ Key )
{
   
   // Check the arguments.  
   if ( FileName == nullptr )
      throw gcnew ArgumentNullException( L"FileName" );

   if ( SignedFileName == nullptr )
      throw gcnew ArgumentNullException( L"SignedFileName" );

   if ( Key == nullptr )
      throw gcnew ArgumentNullException( L"Key" );

   
   // 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 it's name.
   doc->Load( gcnew XmlTextReader( FileName ) );
   
   // Create a SignedXml object.
   SignedXml^ signedXml = gcnew SignedXml( doc );
   
   // Add the key to the SignedXml document. 
   signedXml->SigningKey = Key;
   
   // Get the signature object from the SignedXml object.
   Signature^ XMLSignature = signedXml->Signature;
   
   // Create a reference to be signed.  Pass "" 
   // to specify that all of the current XML
   // document should be signed.
   Reference^ reference = gcnew Reference( L"" );
   
   // Add an enveloped transformation to the reference.
   XmlDsigEnvelopedSignatureTransform^ env = gcnew XmlDsigEnvelopedSignatureTransform;
   reference->AddTransform( env );
   
   // Add the Reference object to the Signature object.
   XMLSignature->SignedInfo->AddReference( reference );
   
   // Add an RSAKeyValue KeyInfo (optional; helps recipient find key to validate).
   KeyInfo^ keyInfo = gcnew KeyInfo;
   keyInfo->AddClause( gcnew RSAKeyValue( dynamic_cast<RSA^>(Key) ) );
   
   // Add the KeyInfo object to the Reference object.
   XMLSignature->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 ( dynamic_cast<XmlDeclaration^>(doc->FirstChild) )
   {
      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.
static Boolean VerifyXmlFile( String^ Name )
{
   
   // Check the arguments.  
   if ( Name == nullptr )
      throw gcnew ArgumentNullException( L"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( L"Signature" );
   
   // Load the signature node.
   signedXml->LoadXml( dynamic_cast<XmlElement^>(nodeList->Item( 0 )) );
   
   // Check the signature and return the result.
   return signedXml->CheckSignature();
}

int main()
{
   
   // Generate a signing key.
   RSA^ Key = RSA::Create();
   try
   {
      
      // Sign an XML file and save the signature to a 
      // new file.
      SignXmlFile( L"Test.xml", L"SignedExample.xml", Key );
      Console::WriteLine( L"XML file signed." );
      
      // Verify the signature of the signed XML.
      Console::WriteLine( L"Verifying signature..." );
      bool result = VerifyXmlFile( L"SignedExample.xml" );
      
      // Display the results of the signature verification to 
      // the console.
      if ( result )
      {
         Console::WriteLine( L"The XML signature is valid." );
      }
      else
      {
         Console::WriteLine( L"The XML signature is not valid." );
      }
   }
   catch ( CryptographicException^ e ) 
   {
      Console::WriteLine( e->Message );
   }
   finally
   {
      
      // Clear resources associated with the 
      // RSA instance.
      Key->Clear();
   }

   return 1;
}

//
// This example signs an XML file using an
// envelope signature. It then verifies the
// signed XML.
//
using System;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
using System.Text;
using System.Xml;

public class SignVerifyEnvelope
{

    public static void Main(String[] args)
    {
        // Generate a signing key.
       RSA Key = RSA.Create();

       try
       {

           // Sign an XML file and save the signature to a
           // new file.
           SignXmlFile("Test.xml", "SignedExample.xml", Key);
           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);
       }
       finally
       {
           // Clear resources associated with the
           // RSA instance.
           Key.Clear();
       }
   }

    // Sign an XML file and save the signature in a new file.
    public static void SignXmlFile(string FileName, string SignedFileName, RSA Key)
    {
        // Check the arguments.
        if (FileName == null)
            throw new ArgumentNullException("FileName");
        if (SignedFileName == null)
            throw new ArgumentNullException("SignedFileName");
        if (Key == null)
            throw new ArgumentNullException("Key");

        // Create a new XML document.
        XmlDocument doc = new XmlDocument();

        // Format the document to ignore white spaces.
        doc.PreserveWhitespace = false;

        // Load the passed XML file using it's name.
        doc.Load(new XmlTextReader(FileName));

        // Create a SignedXml object.
        SignedXml signedXml = new SignedXml(doc);

        // Add the key to the SignedXml document.
        signedXml.SigningKey = Key;

        // Get the signature object from the SignedXml object.
        Signature XMLSignature = signedXml.Signature;

        // Create a reference to be signed.  Pass ""
        // to specify that all of the current XML
        // document should be signed.
        Reference reference = new Reference("");

        // Add an enveloped transformation to the reference.
        XmlDsigEnvelopedSignatureTransform env = new XmlDsigEnvelopedSignatureTransform();
        reference.AddTransform(env);

        // Add the Reference object to the Signature object.
        XMLSignature.SignedInfo.AddReference(reference);

        // Add an RSAKeyValue KeyInfo (optional; helps recipient find key to validate).
        KeyInfo keyInfo = new KeyInfo();
        keyInfo.AddClause(new RSAKeyValue((RSA)Key));

        // Add the KeyInfo object to the Reference object.
        XMLSignature.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 is XmlDeclaration)
        {
            doc.RemoveChild(doc.FirstChild);
        }

        // Save the signed XML document to a file specified
        // using the passed string.
        XmlTextWriter xmltw = new XmlTextWriter(SignedFileName, new UTF8Encoding(false));
        doc.WriteTo(xmltw);
        xmltw.Close();
    }
    // Verify the signature of an XML file and return the result.
    public static Boolean VerifyXmlFile(String Name)
    {
        // Check the arguments.
        if (Name == null)
            throw new ArgumentNullException("Name");

        // Create a new XML document.
        XmlDocument xmlDocument = new 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 = new SignedXml(xmlDocument);

        // Find the "Signature" node and create a new
        // XmlNodeList object.
        XmlNodeList nodeList = xmlDocument.GetElementsByTagName("Signature");

        // Load the signature node.
        signedXml.LoadXml((XmlElement)nodeList[0]);

        // Check the signature and return the result.
        return signedXml.CheckSignature();
    }
}

' This example signs an XML file using an
' envelope signature. It then verifies the 
' signed XML.
'
Imports System.Security.Cryptography
Imports System.Security.Cryptography.Xml
Imports System.Text
Imports System.Xml



Module SignVerifyEnvelope


    Sub Main(ByVal args() As String)
        ' Generate a signing key.
        Dim Key As RSA = RSA.Create()

        Try

            ' Sign an XML file and save the signature to a 
            ' new file.
            SignXmlFile("Test.xml", "SignedExample.xml", Key)
            Console.WriteLine("XML file signed.")

            ' Verify the signature of the signed XML.
            Console.WriteLine("Verifying signature...")

            Dim result As Boolean = VerifyXmlFile("SignedExample.xml")

            ' Display the results of the signature verification to 
            ' the console.
            If result Then
                Console.WriteLine("The XML signature is valid.")
            Else
                Console.WriteLine("The XML signature is not valid.")
            End If
        Catch e As CryptographicException
            Console.WriteLine(e.Message)
        Finally
            ' Clear resources associated with the 
            ' RSA instance.
            Key.Clear()
        End Try

    End Sub


    ' Sign an XML file and save the signature in a new file.
    Sub SignXmlFile(ByVal FileName As String, ByVal SignedFileName As String, ByVal Key As RSA)
        ' Check the arguments.  
        If FileName Is Nothing Then
            Throw New ArgumentNullException("FileName")
        End If
        If SignedFileName Is Nothing Then
            Throw New ArgumentNullException("SignedFileName")
        End If
        If Key Is Nothing Then
            Throw New ArgumentNullException("Key")
        End If

        ' Create a new XML document.
        Dim doc As New XmlDocument()

        ' Format the document to ignore white spaces.
        doc.PreserveWhitespace = False

        ' Load the passed XML file using it's name.
        doc.Load(New XmlTextReader(FileName))

        ' Create a SignedXml object.
        Dim signedXml As New SignedXml(doc)

        ' Add the key to the SignedXml document. 
        signedXml.SigningKey = Key

        ' Get the signature object from the SignedXml object.
        Dim XMLSignature As Signature = signedXml.Signature

        ' Create a reference to be signed.  Pass "" 
        ' to specify that all of the current XML
        ' document should be signed.
        Dim reference As New Reference("")

        ' Add an enveloped transformation to the reference.
        Dim env As New XmlDsigEnvelopedSignatureTransform()
        reference.AddTransform(env)

        ' Add the Reference object to the Signature object.
        XMLSignature.SignedInfo.AddReference(reference)

        ' Add an RSAKeyValue KeyInfo (optional; helps recipient find key to validate).
        Dim keyInfo As New KeyInfo()
        keyInfo.AddClause(New RSAKeyValue(CType(Key, RSA)))

        ' Add the KeyInfo object to the Reference object.
        XMLSignature.KeyInfo = keyInfo

        ' Compute the signature.
        signedXml.ComputeSignature()

        ' Get the XML representation of the signature and save
        ' it to an XmlElement object.
        Dim xmlDigitalSignature As XmlElement = signedXml.GetXml()

        ' Append the element to the XML document.
        doc.DocumentElement.AppendChild(doc.ImportNode(xmlDigitalSignature, True))


        If TypeOf doc.FirstChild Is XmlDeclaration Then
            doc.RemoveChild(doc.FirstChild)
        End If

        ' Save the signed XML document to a file specified
        ' using the passed string.
        Dim xmltw As New XmlTextWriter(SignedFileName, New UTF8Encoding(False))
        doc.WriteTo(xmltw)
        xmltw.Close()

    End Sub

    ' Verify the signature of an XML file and return the result.
    Function VerifyXmlFile(ByVal Name As String) As [Boolean]
        ' Check the arguments.  
        If Name Is Nothing Then
            Throw New ArgumentNullException("Name")
        End If
        ' Create a new XML document.
        Dim xmlDocument As New 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.
        Dim signedXml As New SignedXml(xmlDocument)

        ' Find the "Signature" node and create a new
        ' XmlNodeList object.
        Dim nodeList As XmlNodeList = xmlDocument.GetElementsByTagName("Signature")

        ' Load the signature node.
        signedXml.LoadXml(CType(nodeList(0), XmlElement))

        ' Check the signature and return the result.
        Return signedXml.CheckSignature()

    End Function
End Module

The following code example uses the Signature property to sign and verify a Uniform Resource Identifier (URI) addressable object using a detached signature.

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

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


namespace Sample
{
    public ref class SignVerifyEnvelope
    {
    public:
        static void Work()
        {
            // Generate a signing key.
            RSA^ key = RSA::Create();

            try
            {

                // Sign the detached resource and save the 
                // signature in an XML file.
                SignDetachedResource("http://www.microsoft.com",
                    "SignedExample.xml", key);

                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.");
                }
                Console::ReadLine();
            }

            catch (CryptographicException^ ex)
            {
                Console::WriteLine(ex->Message);
            }
            finally
            {
                // Clear resources associated with the 
                // RSA instance.
                key->Clear();
            }
        }


        // Sign an XML file and save the signature in a new file.
        static void SignDetachedResource(String^ uri, 
            String^ xmlFileName, RSA^ key)
        {
            // Check the arguments.  
            if (uri->Length == 0)
            {
                throw gcnew ArgumentException("uri");
            }
            if (xmlFileName->Length == 0)
            {
                throw gcnew ArgumentException("xmlFileName");
            } 
            if (key->KeySize == 0)
            {
                throw gcnew ArgumentException("key");
            }
            // Create a SignedXml object.
            SignedXml^ signedXml = gcnew SignedXml();

            // Assign the key to the SignedXml object.
            signedXml->SigningKey = key;

            // Get the signature object from the SignedXml object.
            Signature^ xmlSignature = signedXml->Signature;

            // Create a reference to be signed.
            Reference^ reference = gcnew Reference();

            // Add the passed URI to the reference object.
            reference->Uri = uri;

            // Add the Reference object to the Signature object.
            xmlSignature->SignedInfo->AddReference(reference);

            // Add an RSAKeyValue KeyInfo (optional; helps recipient
            // find key to validate).
            KeyInfo^ keyInfo = gcnew KeyInfo();
            keyInfo->AddClause(
                gcnew RSAKeyValue(key));

            // Add the KeyInfo object to the Reference object.
            xmlSignature->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();

            // Save the signed XML document to a file specified
            // using the passed string.
            XmlTextWriter^ xmlTextWriter = gcnew XmlTextWriter(
                xmlFileName, gcnew UTF8Encoding(false));

            xmlDigitalSignature->WriteTo(xmlTextWriter);
            xmlTextWriter->Close();
        }


        // Verify the signature of an XML file and return the result.
        static Boolean VerifyXmlFile(String^ documentName)
        {
            // Check the arguments.  
            if (documentName->Length == 0)
            {
                throw gcnew ArgumentException("documentName");
            }
            // 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(documentName);

            // 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(
                (XmlElement^) nodeList->Item(0));

            // Check the signature and return the result.
            return signedXml->CheckSignature();
        }
    };
}


int main()
{
    Sample::SignVerifyEnvelope::Work();
}

//
// This example signs a URL using an
// envelope signature. It then verifies the
// signed XML.
//
using System;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
using System.Text;
using System.Xml;

public class SignVerifyEnvelope
{

    public static void Main(String[] args)
    {
        // Generate a signing key.
       RSA Key = RSA.Create();

       try
       {

           // Sign the detached resource and save the signature in an XML file.
           SignDetachedResource("http://www.microsoft.com", "SignedExample.xml", Key);

           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);
       }
       finally
       {
           // Clear resources associated with the
           // RSA instance.
           Key.Clear();
       }
   }

    // Sign an XML file and save the signature in a new file.
    public static void SignDetachedResource(string URIString, string XmlSigFileName, RSA Key)
    {
        // Check the arguments.
        if (URIString == null)
            throw new ArgumentNullException("URIString");
        if (XmlSigFileName == null)
            throw new ArgumentNullException("XmlSigFileName");
        if (Key == null)
            throw new ArgumentNullException("Key");

        // Create a SignedXml object.
        SignedXml signedXml = new SignedXml();

        // Assign the key to the SignedXml object.
        signedXml.SigningKey = Key;

        // Get the signature object from the SignedXml object.
        Signature XMLSignature = signedXml.Signature;

        // Create a reference to be signed.
        Reference reference = new Reference();

        // Add the passed URI to the reference object.
        reference.Uri = URIString;

        // Add the Reference object to the Signature object.
        XMLSignature.SignedInfo.AddReference(reference);

        // Add an RSAKeyValue KeyInfo (optional; helps recipient find key to validate).
        KeyInfo keyInfo = new KeyInfo();
        keyInfo.AddClause(new RSAKeyValue((RSA)Key));

        // Add the KeyInfo object to the Reference object.
        XMLSignature.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();

        // Save the signed XML document to a file specified
        // using the passed string.
        XmlTextWriter xmltw = new XmlTextWriter(XmlSigFileName, new UTF8Encoding(false));
        xmlDigitalSignature.WriteTo(xmltw);
        xmltw.Close();
    }

    // Verify the signature of an XML file and return the result.
    public static Boolean VerifyXmlFile(String Name)
    {
        // Check the arguments.
        if (Name == null)
            throw new ArgumentNullException("Name");

        // Create a new XML document.
        XmlDocument xmlDocument = new 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 = new SignedXml(xmlDocument);

        // Find the "Signature" node and create a new
        // XmlNodeList object.
        XmlNodeList nodeList = xmlDocument.GetElementsByTagName("Signature");

        // Load the signature node.
        signedXml.LoadXml((XmlElement)nodeList[0]);

        // Check the signature and return the result.
        return signedXml.CheckSignature();
    }
}

' This example signs a URL using an
' envelope signature. It then verifies the 
' signed XML.
'
Imports System.Security.Cryptography
Imports System.Security.Cryptography.Xml
Imports System.Text
Imports System.Xml



Module SignVerifyEnvelope


    Sub Main(ByVal args() As String)
        ' Generate a signing key.
        Dim Key As RSA = RSA.Create()

        Try

            ' Sign the detached resource and save the signature in an XML file.
            SignDetachedResource("http://www.microsoft.com", "SignedExample.xml", Key)

            Console.WriteLine("XML file signed.")

            ' Verify the signature of the signed XML.
            Console.WriteLine("Verifying signature...")

            Dim result As Boolean = VerifyXmlFile("SignedExample.xml")

            ' Display the results of the signature verification to \
            ' the console.
            If result Then
                Console.WriteLine("The XML signature is valid.")
            Else
                Console.WriteLine("The XML signature is not valid.")
            End If
        Catch e As CryptographicException
            Console.WriteLine(e.Message)
        Finally
            ' Clear resources associated with the 
            ' RSA instance.
            Key.Clear()
        End Try

    End Sub


    ' Sign an XML file and save the signature in a new file.
    Sub SignDetachedResource(ByVal URIString As String, ByVal XmlSigFileName As String, ByVal Key As RSA)
        ' Check the arguments.  
        If URIString Is Nothing Then
            Throw New ArgumentNullException("URIString")
        End If
        If XmlSigFileName Is Nothing Then
            Throw New ArgumentNullException("XmlSigFileName")
        End If
        If Key Is Nothing Then
            Throw New ArgumentNullException("Key")
        End If
        ' Create a SignedXml object.
        Dim signedXml As New SignedXml()

        ' Assign the key to the SignedXml object.
        signedXml.SigningKey = Key

        ' Get the signature object from the SignedXml object.
        Dim XMLSignature As Signature = signedXml.Signature

        ' Create a reference to be signed.
        Dim reference As New Reference()

        ' Add the passed URI to the reference object.
        reference.Uri = URIString

        ' Add the Reference object to the Signature object.
        XMLSignature.SignedInfo.AddReference(reference)

        ' Add an RSAKeyValue KeyInfo (optional; helps recipient find key to validate).
        Dim keyInfo As New KeyInfo()
        keyInfo.AddClause(New RSAKeyValue(CType(Key, RSA)))

        ' Add the KeyInfo object to the Reference object.
        XMLSignature.KeyInfo = keyInfo

        ' Compute the signature.
        signedXml.ComputeSignature()

        ' Get the XML representation of the signature and save
        ' it to an XmlElement object.
        Dim xmlDigitalSignature As XmlElement = signedXml.GetXml()

        ' Save the signed XML document to a file specified
        ' using the passed string.
        Dim xmltw As New XmlTextWriter(XmlSigFileName, New UTF8Encoding(False))
        xmlDigitalSignature.WriteTo(xmltw)
        xmltw.Close()

    End Sub



    ' Verify the signature of an XML file and return the result.
    Function VerifyXmlFile(ByVal Name As String) As [Boolean]
        ' Check the arguments.  
        If Name Is Nothing Then
            Throw New ArgumentNullException("Name")
        End If
        ' Create a new XML document.
        Dim xmlDocument As New 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.
        Dim signedXml As New SignedXml(xmlDocument)

        ' Find the "Signature" node and create a new
        ' XmlNodeList object.
        Dim nodeList As XmlNodeList = xmlDocument.GetElementsByTagName("Signature")

        ' Load the signature node.
        signedXml.LoadXml(CType(nodeList(0), XmlElement))

        ' Check the signature and return the result.
        Return signedXml.CheckSignature()

    End Function
End Module

Remarks

The Signature property represents the <Signature> element of an XML digital signature using a Signature object contained within the property. The <Signature> element is the root element used for XML digital signature creation and verification.

Use the Signature property to retrieve the Signature object used by the SignedXml object.

For more information about the <Signature> element, see the XMLDSIG specification.