Export (0) Print
Expand All

XmlDsigEnvelopedSignatureTransform Class

Represents the enveloped signature transform for an XML digital signature as defined by the W3C.

Namespace:  System.Security.Cryptography.Xml
Assembly:  System.Security (in System.Security.dll)

public ref class XmlDsigEnvelopedSignatureTransform : public Transform

The XmlDsigEnvelopedSignatureTransform class removes the <Signature> element from an XML document before the digest is computed. With this transform, you can sign and verify all elements of an XML document except the XML digital signature elements.

Although you can create and insert a signature into an XML document, verifying the modified document using the embedded signature will fail because the document now has additional elements. This transform removes the <Signature> element and allows you to verify the document using its original form.

Use the XmlDsigEnvelopedSignatureTransform class whenever you create an enveloped signature.

For more information about the enveloped signature transform, see Section 6.6.4 of the XMLDSIG specification, which is available from the W3C at www.w3.org/TR/xmldsig-core/.

This section contains two code examples. The first example demonstrates how to sign an XML file using an envelope signature. The second example demonstrates how to use members of the XmlDsigEnvelopedSignatureTransform class.

Example #1

// 
// 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::X509Certificates;
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^ 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 its 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;

   // Create a reference to be signed.
   Reference^ reference = gcnew Reference;
   reference->Uri = "";

   // 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 KeyInfo (optional; helps recipient find key to validate).
   KeyInfo^ keyInfo = gcnew KeyInfo;
   keyInfo->AddClause( gcnew RSAKeyValue( safe_cast<RSA^>(Key) ) );
   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 a signing key.
      RSACryptoServiceProvider^ Key = gcnew RSACryptoServiceProvider;

      // 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", 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 );
   }

}

Example #2

#using <System.dll>
#using <System.Xml.dll>
#using <System.Security.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
using namespace System::Security::Cryptography;
using namespace System::Security::Cryptography::Xml;
using namespace System::Security::Cryptography::X509Certificates;

public ref class EnvelopedSignatureSample
{
private:
    static String^ Certificate =  "..\\..\\my509.cer";

    // Encrypt the text in the specified XmlDocument. 
public:
    static void ShowTransformProperties(XmlDocument^ xmlDoc)
    {
        XmlDsigEnvelopedSignatureTransform^ xmlTransform =
            gcnew XmlDsigEnvelopedSignatureTransform();

        // Ensure the transform is using the proper algorithm.
        xmlTransform->Algorithm =
            SignedXml::XmlDsigEnvelopedSignatureTransformUrl;

        // Retrieve the XML representation of the current transform.
        XmlElement^ xmlInTransform = xmlTransform->GetXml();

        Console::WriteLine("\nXml representation of the current transform: ");
        Console::WriteLine(xmlInTransform->OuterXml);

        // Retrieve the valid input types for the current transform. 
        array<Type^>^ validInTypes = xmlTransform->InputTypes;

        // Verify the xmlTransform can accept the XMLDocument as an 
        // input type. 
        for (int i = 0; i < validInTypes->Length; i++)
        {
            if (validInTypes[i] == xmlDoc->GetType())
            {
                // Load the document into the transfrom.
                xmlTransform->LoadInput(xmlDoc);

                bool IncludeComments = true;
                // This transform is created for demonstration purposes.
                XmlDsigEnvelopedSignatureTransform^ secondTransform =
                    gcnew XmlDsigEnvelopedSignatureTransform(IncludeComments);

                String^ classDescription = secondTransform->ToString();

                // This call does not perform as expected. 
                // An enveloped signature has no inner XML elements
                secondTransform->LoadInnerXml(xmlDoc->SelectNodes("//."));

                break;
            }
        }

        array<Type^>^ validOutTypes = xmlTransform->OutputTypes;

        for (int i = validOutTypes->Length-1; i >= 0; i--)
        {
            if (validOutTypes[i] == System::Xml::XmlDocument::typeid)
            {
                Type^ xmlDocumentType = System::Xml::XmlDocument::typeid;
                XmlDocument^ xmlDocumentOutput = (XmlDocument^)
                    xmlTransform->GetOutput(xmlDocumentType);

                // Display to the console the Xml before and after 
                // encryption.
                Console::WriteLine("Result of the GetOutput method call" +
                    " from the current transform: " +
                    xmlDocumentOutput->OuterXml);

                break;
            }
            else if (validOutTypes[i] == System::Xml::XmlNodeList::typeid)
            {
                Type^ xmlNodeListType = System::Xml::XmlNodeList::typeid;
                XmlNodeList^ xmlNodes = (XmlNodeList^)
                    xmlTransform->GetOutput(xmlNodeListType);

                // Display to the console the Xml before and after 
                // encryption.
                Console::WriteLine("Encoding the following message: " +
                    xmlDoc->InnerText);

                Console::WriteLine("Nodes of the XmlNodeList retrieved " +
                    "from GetOutput:");
                for (int j = 0; j < xmlNodes->Count; j++)
                {
                    Console::WriteLine("Node " + j +
                        " has the following name: " +
                        xmlNodes->Item(j)->Name +
                        " and the following InnerXml: " +
                        xmlNodes->Item(j)->InnerXml);
                }

                break;
            }
            else
            {
                Object^ outputObject = xmlTransform->GetOutput();
            }
        }
    }

    // Create an XML document describing various products. 
public:
    static XmlDocument^ LoadProducts()
    {
        XmlDocument^ xmlDoc = gcnew XmlDocument();

        String^ contosoProducts = "<PRODUCTS>" +
            "<PRODUCT><ID>123</ID><DESCRIPTION>Router" + 
            "</DESCRIPTION></PRODUCT>" +
            "<PRODUCT><ID>456</ID><DESCRIPTION>Keyboard" +
            "</DESCRIPTION></PRODUCT>" +
            "<PRODUCT><ID>789</ID><DESCRIPTION>Monitor" +
            "</DESCRIPTION></PRODUCT>" +
            "</PRODUCTS>";

        xmlDoc->LoadXml(contosoProducts);
        return xmlDoc;
    }

    // Create a signature and add it to the specified document. 
public:
    static void SignDocument(XmlDocument^ xmlDoc)
    {
        // Generate a signing key.
        RSACryptoServiceProvider^ key = gcnew RSACryptoServiceProvider();

        // Create a SignedXml object.
        SignedXml^ signedDocument = gcnew SignedXml(xmlDoc);

        // Add the key to the SignedXml document.
        signedDocument->SigningKey = key;

        // Create a reference to be signed.
        Reference^ referenceToBeSigned = gcnew Reference();
        referenceToBeSigned->Uri = "";

        // Add an enveloped transformation to the reference.
        referenceToBeSigned->AddTransform(
            gcnew XmlDsigEnvelopedSignatureTransform());

        // Add the reference to the SignedXml object.
        signedDocument->AddReference(referenceToBeSigned);

        if(File::Exists(Certificate))
        {
            // Create a new KeyInfo object.
            KeyInfo^ info = gcnew KeyInfo();

            // Load the X509 certificate.
            X509Certificate^ certFromFile =
                X509Certificate::CreateFromCertFile(Certificate);

            // Load the certificate into a KeyInfoX509Data object 
            // and add it to the KeyInfo object.
            info->AddClause(gcnew KeyInfoX509Data(certFromFile));

            // Add the KeyInfo object to the SignedXml object.
            signedDocument->KeyInfo = info;
        }
        else
        {
            Console::WriteLine("Unable to locate the following file: " +
                Certificate);
        }

        // Compute the signature.
        signedDocument->ComputeSignature();

        // Add the signature branch to the original tree so it is enveloped.
        xmlDoc->DocumentElement->AppendChild(signedDocument->GetXml());
    }

    // Resolve the specified base and relative Uri's . 
public:
    static Uri^ ResolveUris(Uri^ baseUri, String^ relativeUri)
    {
        XmlUrlResolver^ xmlResolver = gcnew XmlUrlResolver();
        xmlResolver->Credentials =
            System::Net::CredentialCache::DefaultCredentials;

        XmlDsigEnvelopedSignatureTransform^ xmlTransform =
            gcnew XmlDsigEnvelopedSignatureTransform();
        xmlTransform->Resolver = xmlResolver;

        Uri^ absoluteUri = xmlResolver->ResolveUri(baseUri, relativeUri);

        if (absoluteUri != nullptr)
        {
            Console::WriteLine(
                "\nResolved the base Uri and relative Uri to the following:");
            Console::WriteLine(absoluteUri->ToString());
        }
        else
        {
            Console::WriteLine(
                "Unable to resolve the base Uri and relative Uri");
        }
        return absoluteUri;
    }
};

[STAThread]
int main()
{
    // Encrypt an XML message
    XmlDocument^ productsXml = EnvelopedSignatureSample::LoadProducts();
    EnvelopedSignatureSample::ShowTransformProperties(productsXml);

    EnvelopedSignatureSample::SignDocument(productsXml);
    EnvelopedSignatureSample::ShowTransformProperties(productsXml);

    // Use XmlDsigEnvelopedSignatureTransform to resolve a Uri.
    Uri^ baseUri = gcnew Uri("http://www.contoso.com");
    String^ relativeUri = "xml";
    Uri^ absoluteUri = 
        EnvelopedSignatureSample::ResolveUris(baseUri, relativeUri);

    Console::WriteLine("This sample completed successfully; " +
        "press Enter to exit.");
    Console::ReadLine();
}

// 
// This sample produces the following output: 
// 
// Xml representation of the current transform: 
// <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped- 
// signature" xmlns="http://www.w3.org/2000/09/xmldsig#" /> 
// Result of the GetOutput method call from the current transform: <PRODUCTS> 
// <PRODUCT><ID>123</ID><DESCRIPTION>Router</DESCRIPTION></PRODUCT><PRODUCT> 
// <ID>456</ID><DESCRIPTION>Keyboard</DESCRIPTION></PRODUCT><PRODUCT><ID>789 
// </ID><DESCRIPTION>Monitor</DESCRIPTION></PRODUCT></PRODUCTS> 
// Unable to load the following file: ..\\my509.cer 
// 
// Xml representation of the current transform: 
// <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped- 
// signature" xmlns="http://www.w3.org/2000/09/xmldsig#" /> 
// Result of the GetOutput method call from the current transform: <PRODUCTS> 
// <PRODUCT><ID>123</ID><DESCRIPTION>Router</DESCRIPTION></PRODUCT><PRODUCT> 
// <ID>456</ID><DESCRIPTION>Keyboard</DESCRIPTION></PRODUCT><PRODUCT><ID>789 
// </ID><DESCRIPTION>Monitor</DESCRIPTION></PRODUCT><Signature xmlns= 
// "http://www.w3.org/2000/09/xmldsig#"><SignedInfo><CanonicalizationMethod
// Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" />
// <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
// <Reference URI=""><Transforms><Transform Algorithm="http://www.w3.org/2000 
// /09/xmldsig#enveloped-signature" /></Transforms><DigestMethod Algorithm= 
// "http://www.w3.org/2000/09/xmldsig#sha1" /><DigestValue>KvPW6HUiIUMEDS0YSoT
// gpo2JPbA=</DigestValue></Reference></SignedInfo><SignatureValue>c/njCGDru/a 
// WAmWG83I+mWO040xOzxvmNx0b0o8ZyPc9j5VwApdAt103OGBtB1H6EkOvt7Ekw+PVuUo8m5LzLP 
// yaTxUDMbb2kZZ5itSkGD4rmMUMUMuzrkAoquJZjxeOydBJ2CMehV2rE3RMPLIwRX176DZVy5JKU 
// 6Cb7PR2Rpw=</SignatureValue></Signature></PRODUCTS> 
// 
// Resolved the base Uri and relative Uri to the following: 
// http://www.contoso.com/xml 
// This sample completed successfully; press Enter to exit.

System::Object
  System.Security.Cryptography.Xml::Transform
    System.Security.Cryptography.Xml::XmlDsigEnvelopedSignatureTransform

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

Community Additions

ADD
Show:
© 2014 Microsoft