XmlDsigExcC14NTransform Class

Definition

Namespace:

System.Security.Cryptography.Xml

Assembly:

System.Security.Cryptography.Xml.dll

Represents the exclusive C14N XML canonicalization transform for a digital signature as defined by the World Wide Web Consortium (W3C), without comments.

public ref class XmlDsigExcC14NTransform : System::Security::Cryptography::Xml::Transform

public class XmlDsigExcC14NTransform : System.Security.Cryptography.Xml.Transform

type XmlDsigExcC14NTransform = class
    inherit Transform

Public Class XmlDsigExcC14NTransform
Inherits Transform

Inheritance

Object

Transform

XmlDsigExcC14NTransform

Derived

System.Security.Cryptography.Xml.XmlDsigExcC14NWithCommentsTransform

Examples

The following code example shows how to sign an XML document with the XmlDsigExcC14NTransform class using an envelope 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::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.
static 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 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;
   
   // Specify a canonicalization method.
   signedXml->SignedInfo->CanonicalizationMethod = SignedXml::XmlDsigExcC14NTransformUrl;
   
   // Set the InclusiveNamespacesPrefixList property.        
   XmlDsigExcC14NTransform^ canMethod = dynamic_cast<XmlDsigExcC14NTransform^>(signedXml->SignedInfo->CanonicalizationMethodObject);
   canMethod->InclusiveNamespacesPrefixList = L"Sign";
   
   // Create a reference to be signed.
   Reference^ reference = gcnew Reference;
   reference->Uri = L"";
   
   // 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( dynamic_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 ( 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 )
{
   
   // 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();
}


// Create example data to sign.
static void CreateSomeXml( String^ FileName )
{
   
   // Create a new XmlDocument object.
   XmlDocument^ document = gcnew XmlDocument;
   
   // Create a new XmlNode object.
   XmlNode^ node = document->CreateNode( XmlNodeType::Element, L"", L"MyXML", L"Don't_Sign" );
   
   // Append the node to the document.
   document->AppendChild( node );
   
   // Create a new XmlNode object.
   XmlNode^ subnode = document->CreateNode( XmlNodeType::Element, L"", L"TempElement", L"Sign" );
   
   // Add some text to the node.
   subnode->InnerText = L"Here is some data to sign.";
   
   // Append the node to the document.
   document->DocumentElement->AppendChild( subnode );
   
   // 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.
      RSA^ Key = RSA::Create();
      
      // Create an XML file to sign.
      CreateSomeXml( L"Example.xml" );
      Console::WriteLine( L"New XML file created." );
      
      // Sign the XML that was just created and save it in a 
      // new file.
      SignXmlFile( L"Example.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 );
   }

   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.X509Certificates;
using System.Security.Cryptography.Xml;
using System.Text;
using System.Xml;

public class SignVerifyEnvelope
{

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

    // Sign an XML file and save the signature in a new file.
    public static void SignXmlFile(string FileName, string SignedFileName, RSA 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;

        // Specify a canonicalization method.
        signedXml.SignedInfo.CanonicalizationMethod = SignedXml.XmlDsigExcC14NTransformUrl;

        // Set the InclusiveNamespacesPrefixList property.
        XmlDsigExcC14NTransform canMethod = (XmlDsigExcC14NTransform)signedXml.SignedInfo.CanonicalizationMethodObject;
        canMethod.InclusiveNamespacesPrefixList = "Sign";

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

        // Add an enveloped transformation to the reference.
        XmlDsigEnvelopedSignatureTransform env = new 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 = new KeyInfo();
        keyInfo.AddClause(new RSAKeyValue((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 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)
    {
        // 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();
    }

    // Create example data to sign.
    public static void CreateSomeXml(string FileName)
    {
        // Create a new XmlDocument object.
        XmlDocument document = new XmlDocument();

        // Create a new XmlNode object.
        XmlNode node = document.CreateNode(XmlNodeType.Element, "", "MyXML", "Don't_Sign");

        // Append the node to the document.
        document.AppendChild(node);

        // Create a new XmlNode object.
        XmlNode subnode = document.CreateNode(XmlNodeType.Element, "", "TempElement", "Sign");

        // Add some text to the node.
        subnode.InnerText = "Here is some data to sign.";

        // Append the node to the document.
        document.DocumentElement.AppendChild(subnode);

        // Save the XML document to the file name specified.
        XmlTextWriter xmltw = new XmlTextWriter(FileName, new UTF8Encoding(false));
        document.WriteTo(xmltw);
        xmltw.Close();
    }
}

'
' This example signs an XML file using an
' envelope signature. It then verifies the 
' signed XML.
'
Imports System.Security.Cryptography
Imports System.Security.Cryptography.X509Certificates
Imports System.Security.Cryptography.Xml
Imports System.Text
Imports System.Xml



Module SignVerifyEnvelope


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

        ' Specify a canonicalization method.
        signedXml.SignedInfo.CanonicalizationMethod = signedXml.XmlDsigExcC14NTransformUrl

        ' Set the InclusiveNamespacesPrefixList property. 
        Dim canMethod As XmlDsigExcC14NTransform = CType(signedXml.SignedInfo.CanonicalizationMethodObject, XmlDsigExcC14NTransform)
        canMethod.InclusiveNamespacesPrefixList = "Sign"

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

        ' Add an enveloped transformation to the reference.
        Dim env As New 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).
        Dim keyInfo As New KeyInfo()
        keyInfo.AddClause(New RSAKeyValue(CType(Key, RSA)))
        signedXml.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]
        ' 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


    ' Create example data to sign.
    Sub CreateSomeXml(ByVal FileName As String)
        ' Create a new XmlDocument object.
        Dim document As New XmlDocument()

        ' Create a new XmlNode object.
        Dim node As XmlNode = document.CreateNode(XmlNodeType.Element, "", "MyXML", "Don't_Sign")

        ' Append the node to the document.
        document.AppendChild(node)

        ' Create a new XmlNode object.
        Dim subnode As XmlNode = document.CreateNode(XmlNodeType.Element, "", "TempElement", "Sign")

        ' Add some text to the node.
        subnode.InnerText = "Here is some data to sign."

        ' Append the node to the document.
        document.DocumentElement.AppendChild(subnode)

        ' Save the XML document to the file name specified.
        Dim xmltw As New XmlTextWriter(FileName, New UTF8Encoding(False))
        document.WriteTo(xmltw)
        xmltw.Close()

    End Sub
End Module

Remarks

The XmlDsigExcC14NTransform class represents the exclusive C14N XML canonicalization transform without comments. This class is similar to the XmlDsigC14NTransform class, which allows a signer to create a digest using the canonical form of an XML document. However, the XmlDsigExcC14NTransform class excludes ancestor context from a canonicalized subdocument.

Use the XmlDsigC14NTransform class when you need to canonicalize an XML subdocument so that it is independent from its XML context. For example, applications such as Web services that use signed XML within complex communication protocols often need to canonicalize XML in this manner. Such applications often envelop XML within various dynamically constructed elements, which can substantially change the document and cause XML signature verification to fail. The XmlDsigExcC14NTransform class solves this problem by excluding such ancestor context from the canonical subdocument.

Typically, you do not create a new instance of a canonicalization transform class. To specify a canonicalization transform, pass the Uniform Resource Identifier (URI) that describes a transform to the CanonicalizationMethod property, which is accessible from the SignedInfo property. To acquire a reference to the canonicalization transform, use the CanonicalizationMethodObject property, which is accessible from the SignedInfo property.

You are required to create a new instance of a canonicalization transform class only when you want to manually hash an XML document or use your own canonicalization algorithm.

The URI that describes the XmlDsigExcC14NWithCommentsTransform class is defined by the XmlDsigExcC14NWithCommentsTransformUrl field.

The URI that describes the XmlDsigExcC14NTransform class is defined by the XmlDsigExcC14NTransformUrl field.

For more information about the exclusive C14N transform, see the W3C XMLDSIG specification. The canonicalization algorithm is defined in the W3C Canonical XML specification.

Constructors

XmlDsigExcC14NTransform()	Initializes a new instance of the XmlDsigExcC14NTransform class.
XmlDsigExcC14NTransform(Boolean, String)	Initializes a new instance of the XmlDsigExcC14NTransform class specifying whether to include comments, and specifying a list of namespace prefixes.
XmlDsigExcC14NTransform(Boolean)	Initializes a new instance of the XmlDsigExcC14NTransform class specifying a value that determines whether to include comments.
XmlDsigExcC14NTransform(String)	Initializes a new instance of the XmlDsigExcC14NTransform class specifying a list of namespace prefixes to canonicalize using the standard canonicalization algorithm.

Properties

Algorithm	Gets or sets the Uniform Resource Identifier (URI) that identifies the algorithm performed by the current transform. (Inherited from Transform)
Context	Gets or sets an XmlElement object that represents the document context under which the current Transform object is running. (Inherited from Transform)
InclusiveNamespacesPrefixList	Gets or sets a string that contains namespace prefixes to canonicalize using the standard canonicalization algorithm.
InputTypes	Gets an array of types that are valid inputs to the LoadInput(Object) method of the current XmlDsigExcC14NTransform object.
OutputTypes	Gets an array of types that are possible outputs from the GetOutput() methods of the current XmlDsigExcC14NTransform object.
PropagatedNamespaces	Gets or sets a Hashtable object that contains the namespaces that are propagated into the signature. (Inherited from Transform)
Resolver	Sets the current XmlResolver object. (Inherited from Transform)

Methods

Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetDigestedOutput(HashAlgorithm)	Returns the digest associated with a XmlDsigExcC14NTransform object.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetInnerXml()	Returns an XML representation of the parameters of a XmlDsigExcC14NTransform object that are suitable to be included as subelements of an XMLDSIG <Transform> element.
GetOutput()	Returns the output of the current XmlDsigExcC14NTransform object.
GetOutput(Type)	Returns the output of the current XmlDsigExcC14NTransform object as an object of the specified type.
GetType()	Gets the Type of the current instance. (Inherited from Object)
GetXml()	Returns the XML representation of the current Transform object. (Inherited from Transform)
LoadInnerXml(XmlNodeList)	Parses the specified XmlNodeList object as transform-specific content of a <Transform> element and configures the internal state of the current XmlDsigExcC14NTransform object to match the <Transform> element.
LoadInput(Object)	When overridden in a derived class, loads the specified input into the current XmlDsigExcC14NTransform object.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)