XmlDsigXPathTransform Class
Definition
Important
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Represents the XPath transform for a digital signature as defined by the W3C.
public ref class XmlDsigXPathTransform : System::Security::Cryptography::Xml::Transformpublic class XmlDsigXPathTransform : System.Security.Cryptography.Xml.Transformtype XmlDsigXPathTransform = class
inherit TransformPublic Class XmlDsigXPathTransform
Inherits Transform- Inheritance
Examples
This section contains two code examples. The first code example shows how to sign and verify an XML document using the XmlDsigXPathTransform class with an envelope signature. This example signs an XML document and saves the signature in a new XML document. The second code example demonstrates how to call members of the XmlDsigXPathTransform class.
Example #1
//
// 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;
// Create the XML that represents the transform.
static XmlDsigXPathTransform^ CreateXPathTransform( String^ XPathString )
{
// Create a new XMLDocument object.
XmlDocument^ doc = gcnew XmlDocument;
// Create a new XmlElement.
XmlElement^ xPathElem = doc->CreateElement( L"XPath" );
// Set the element text to the value
// of the XPath string.
xPathElem->InnerText = XPathString;
// Create a new XmlDsigXPathTransform object.
XmlDsigXPathTransform^ xForm = gcnew XmlDsigXPathTransform;
// Load the XPath XML from the element.
xForm->LoadInnerXml( xPathElem->SelectNodes( L"." ) );
// Return the XML that represents the transform.
return xForm;
}
// Sign an XML file and save the signature in a new file.
static void SignXmlFile( String^ FileName, String^ SignedFileName, RSA^ Key, String^ XPathString )
{
// 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;
// Create a reference to be signed.
Reference^ reference = gcnew Reference;
reference->Uri = L"";
// Create an XmlDsigXPathTransform object using
// the helper method 'CreateXPathTransform' defined
// later in this sample.
XmlDsigXPathTransform^ XPathTransform = CreateXPathTransform( XPathString );
// Add the transform to the reference.
reference->AddTransform( XPathTransform );
// 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 ) );
// 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()
{
// Generate a signing key.
RSA^ Key = RSA::Create();
try
{
// 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, L"ancestor-or-self::TempElement" );
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
{
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.X509Certificates;
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
{
// 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, "ancestor-or-self::TempElement");
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
{
Key.Clear();
}
}
// Sign an XML file and save the signature in a new file.
public static void SignXmlFile(string FileName, string SignedFileName, RSA Key, string XPathString)
{
// 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;
// Create a reference to be signed.
Reference reference = new Reference();
reference.Uri = "";
// Create an XmlDsigXPathTransform object using
// the helper method 'CreateXPathTransform' defined
// later in this sample.
XmlDsigXPathTransform XPathTransform = CreateXPathTransform(XPathString);
// Add the transform to the reference.
reference.AddTransform(XPathTransform);
// 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));
// 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 the XML that represents the transform.
private static XmlDsigXPathTransform CreateXPathTransform(string XPathString)
{
// Create a new XMLDocument object.
XmlDocument doc = new XmlDocument();
// Create a new XmlElement.
XmlElement xPathElem = doc.CreateElement("XPath");
// Set the element text to the value
// of the XPath string.
xPathElem.InnerText = XPathString;
// Create a new XmlDsigXPathTransform object.
XmlDsigXPathTransform xForm = new XmlDsigXPathTransform();
// Load the XPath XML from the element.
xForm.LoadInnerXml(xPathElem.SelectNodes("."));
// Return the XML that represents the transform.
return xForm;
}
// 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)
' Generate a signing key.
Dim Key As RSA = RSA.Create()
Try
' 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, "ancestor-or-self::TempElement")
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
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, ByVal XPathString As String)
' 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
' Create a reference to be signed.
Dim reference As New Reference()
reference.Uri = ""
' Create an XmlDsigXPathTransform object using
' the helper method 'CreateXPathTransform' defined
' later in this sample.
Dim XPathTransform As XmlDsigXPathTransform = CreateXPathTransform(XPathString)
' Add the transform to the reference.
reference.AddTransform(XPathTransform)
' 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))
' 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 the XML that represents the transform.
Function CreateXPathTransform(ByVal XPathString As String) As XmlDsigXPathTransform
' Create a new XMLDocument object.
Dim doc As New XmlDocument()
' Create a new XmlElement.
Dim xPathElem As XmlElement = doc.CreateElement("XPath")
' Set the element text to the value
' of the XPath string.
xPathElem.InnerText = XPathString
' Create a new XmlDsigXPathTransform object.
Dim xForm As New XmlDsigXPathTransform()
' Load the XPath XML from the element.
xForm.LoadInnerXml(xPathElem.SelectNodes("."))
' Return the XML that represents the transform.
Return xForm
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
Example #2
using System;
using System.IO;
using System.Xml;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
class Class1
{
[STAThread]
static void Main(string[] args)
{
// Encrypt a sample XML string.
XmlDocument productsXml = LoadProducts();
ShowTransformProperties(productsXml);
// Encrypt an XPath Xml string.
XmlDocument transformXml = LoadTransformByXml();
ShowTransformProperties(transformXml);
// Use XmlDsigXPathTransform to resolve a Uri.
Uri baseUri = new Uri("http://www.contoso.com");
string relativeUri = "xml";
Uri absoluteUri = ResolveUris(baseUri, relativeUri);
Console.WriteLine("This sample completed successfully; " +
"press Enter to exit.");
Console.ReadLine();
}
// Encrypt the text in the specified XmlDocument.
private static void ShowTransformProperties(XmlDocument xmlDoc)
{
// Create a new XMLDocument object.
XmlDocument doc = new XmlDocument();
// Create a new XmlElement.
XmlElement xPathElem = doc.CreateElement("XPath");
// Set the element text to the value
// of the XPath string.
xPathElem.InnerText = "ancestor-or-self::PRODUCTS";
// Create a new XmlDsigXPathTransform object.
XmlDsigXPathTransform xmlTransform = new XmlDsigXPathTransform();
// Load the XPath XML from the element.
xmlTransform.LoadInnerXml(xPathElem.SelectNodes("."));
// Ensure the transform is using the proper algorithm.
xmlTransform.Algorithm =
SignedXml.XmlDsigXPathTransformUrl;
// 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.
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);
try
{
// This transform is created for demonstration purposes.
XmlDsigXPathTransform secondTransform =
new XmlDsigXPathTransform();
string classDescription = secondTransform.ToString();
xmlTransform.LoadInnerXml(xPathElem.SelectNodes(".")); ;
}
catch (CryptographicException)
{
Console.WriteLine("Caught exception while trying to " +
"load the specified Xml document. The document " +
"requires an XPath element to be valid.");
}
break;
}
}
Type[] validOutTypes = xmlTransform.OutputTypes;
for (int i = validOutTypes.Length - 1; i >= 0; i--)
{
if (validOutTypes[i] == typeof(System.Xml.XmlDocument))
{
try
{
Type xmlDocumentType = typeof(System.Xml.XmlDocument);
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);
}
catch (Exception ex)
{
Console.WriteLine("Unexpected exception caught: " +
ex.ToString());
}
break;
}
else if (validOutTypes[i] == typeof(System.Xml.XmlNodeList))
{
try
{
Type xmlNodeListType = typeof(System.Xml.XmlNodeList);
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);
}
}
catch (Exception ex)
{
Console.WriteLine("Unexpected exception caught: " +
ex.ToString());
}
break;
}
else
{
object outputObject = xmlTransform.GetOutput();
}
}
}
// Create an XML document for the dsig namespace.
private static XmlDocument LoadTransformByXml()
{
XmlDocument xmlDoc = new XmlDocument();
string transformXml = "<Signature><Reference URI=''><Transforms>";
transformXml += "<Transform><XPath ";
transformXml += "xmlns:dsig='http://www.w3.org/2000/09/xmldsig#'>";
transformXml += "not(ancestor-or-self::dsig:Signature)";
transformXml += "</XPath></Transform>";
transformXml += "</Transforms></Reference></Signature>";
xmlDoc.LoadXml(transformXml);
return xmlDoc;
}
// Create an XML document describing various products.
private static XmlDocument LoadProducts()
{
XmlDocument xmlDoc = new XmlDocument();
string contosoProducts = "<PRODUCTS>";
contosoProducts += "<PRODUCT><ID>123</ID>";
contosoProducts += "<DESCRIPTION>Router</DESCRIPTION></PRODUCT>";
contosoProducts += "<PRODUCT><ID>456</ID>";
contosoProducts += "<DESCRIPTION>Keyboard</DESCRIPTION></PRODUCT>";
contosoProducts += "<PRODUCT><ID>789</ID>";
contosoProducts += "<DESCRIPTION>Monitor</DESCRIPTION></PRODUCT>";
contosoProducts += "</PRODUCTS>";
xmlDoc.LoadXml(contosoProducts);
return xmlDoc;
}
// Resolve the specified base and relative Uri's .
private static Uri ResolveUris(Uri baseUri, string relativeUri)
{
XmlUrlResolver xmlResolver = new XmlUrlResolver();
xmlResolver.Credentials =
System.Net.CredentialCache.DefaultCredentials;
XmlDsigXPathTransform xmlTransform =
new XmlDsigXPathTransform();
xmlTransform.Resolver = xmlResolver;
Uri absoluteUri = xmlResolver.ResolveUri(baseUri, relativeUri);
if (absoluteUri != null)
{
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;
}
}
Imports System.IO
Imports System.Xml
Imports System.Security.Cryptography
Imports System.Security.Cryptography.Xml
Class Class1
<STAThread()> _
Shared Sub Main(ByVal args() As String)
' Encrypt a sample XML string.
Dim productsXml As XmlDocument = LoadProducts()
ShowTransformProperties(productsXml)
' Encrypt an XPath Xml string.
Dim transformXml As XmlDocument = LoadTransformByXml()
ShowTransformProperties(transformXml)
' Use XmlDsigXPathTransform to resolve a Uri.
Dim baseUri As New Uri("http://www.contoso.com")
Dim relativeUri As String = "xml"
Dim absoluteUri As Uri = ResolveUris(baseUri, relativeUri)
Console.WriteLine("This sample completed successfully; " + "press Enter to exit.")
Console.ReadLine()
End Sub
' Encrypt the text in the specified XmlDocument.
Private Shared Sub ShowTransformProperties(ByVal xmlDoc As XmlDocument)
' Create a new XMLDocument object.
Dim doc As New XmlDocument()
' Create a new XmlElement.
Dim xPathElem As XmlElement = doc.CreateElement("XPath")
' Set the element text to the value
' of the XPath string.
xPathElem.InnerText = "ancestor-or-self::PRODUCTS"
' Create a new XmlDsigXPathTransform object.
Dim xmlTransform As New XmlDsigXPathTransform()
' Load the XPath XML from the element.
xmlTransform.LoadInnerXml(xPathElem.SelectNodes("."))
' Ensure the transform is using the proper algorithm.
xmlTransform.Algorithm = SignedXml.XmlDsigXPathTransformUrl
' Retrieve the XML representation of the current transform.
Dim xmlInTransform As XmlElement = xmlTransform.GetXml()
Console.WriteLine(vbLf + "Xml representation of the current transform: ")
Console.WriteLine(xmlInTransform.OuterXml)
' Retrieve the valid input types for the current transform.
Dim validInTypes As Type() = xmlTransform.InputTypes
' Verify the xmlTransform can accept the XMLDocument as an
' input type.
Dim i As Integer
For i = 0 To validInTypes.Length
If validInTypes(i).Equals(xmlDoc.GetType()) Then
' Load the document into the transfrom.
xmlTransform.LoadInput(xmlDoc)
Try
' This transform is created for demonstration purposes.
Dim secondTransform As New XmlDsigXPathTransform()
Dim classDescription As String = secondTransform.ToString()
xmlTransform.LoadInnerXml(xPathElem.SelectNodes("."))
Catch
Console.WriteLine("Caught exception while trying to " + "load the specified Xml document. The document " + "requires an XPath element to be valid.")
End Try
Exit For
End If
Next i
Dim validOutTypes As Type() = xmlTransform.OutputTypes
For i = validOutTypes.Length - 1 To 0 Step -1
If validOutTypes(i).Equals(GetType(System.Xml.XmlDocument)) Then
Try
Dim xmlDocumentType As Type = GetType(System.Xml.XmlDocument)
Dim xmlDocumentOutput As XmlDocument = CType(xmlTransform.GetOutput(xmlDocumentType), XmlDocument)
' Display to the console the Xml before and after
' encryption.
Console.WriteLine("Result of the GetOutput method call" + " from the current transform: " + xmlDocumentOutput.OuterXml)
Catch ex As Exception
Console.WriteLine("Unexpected exception caught: " + ex.ToString())
End Try
Exit For
ElseIf validOutTypes(i).Equals(GetType(System.Xml.XmlNodeList)) Then
Try
Dim xmlNodeListType As Type = GetType(System.Xml.XmlNodeList)
Dim xmlNodes As XmlNodeList = CType(xmlTransform.GetOutput(xmlNodeListType), XmlNodeList)
' 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 j As Integer = 0 To xmlNodes.Count - 1
Console.WriteLine("Node " + j + " has the following name: " + xmlNodes.Item(j).Name + " and the following InnerXml: " + xmlNodes.Item(j).InnerXml)
Next
Catch ex As Exception
Console.WriteLine("Unexpected exception caught: " + ex.ToString())
End Try
Exit For
Else
Dim outputObject As Object = xmlTransform.GetOutput()
End If
Next i
End Sub
' Create an XML document for the dsig namespace.
Private Shared Function LoadTransformByXml() As XmlDocument
Dim xmlDoc As New XmlDocument()
Dim transformXml As String = "<Signature><Reference URI=''><Transforms>"
transformXml += "<Transform><XPath "
transformXml += "xmlns:dsig='http://www.w3.org/2000/09/xmldsig#'>"
transformXml += "not(ancestor-or-self::dsig:Signature)"
transformXml += "</XPath></Transform>"
transformXml += "</Transforms></Reference></Signature>"
xmlDoc.LoadXml(transformXml)
Return xmlDoc
End Function 'LoadTransformByXml
' Create an XML document describing various products.
Private Shared Function LoadProducts() As XmlDocument
Dim xmlDoc As New XmlDocument()
Dim contosoProducts As String = "<PRODUCTS>"
contosoProducts += "<PRODUCT><ID>123</ID>"
contosoProducts += "<DESCRIPTION>Router</DESCRIPTION></PRODUCT>"
contosoProducts += "<PRODUCT><ID>456</ID>"
contosoProducts += "<DESCRIPTION>Keyboard</DESCRIPTION></PRODUCT>"
contosoProducts += "<PRODUCT><ID>789</ID>"
contosoProducts += "<DESCRIPTION>Monitor</DESCRIPTION></PRODUCT>"
contosoProducts += "</PRODUCTS>"
xmlDoc.LoadXml(contosoProducts)
Return xmlDoc
End Function 'LoadProducts
' Resolve the specified base and relative Uri's .
Private Shared Function ResolveUris(ByVal baseUri As Uri, ByVal relativeUri As String) As Uri
Dim xmlResolver As New XmlUrlResolver()
xmlResolver.Credentials = System.Net.CredentialCache.DefaultCredentials
Dim xmlTransform As New XmlDsigXPathTransform()
xmlTransform.Resolver = xmlResolver
Dim absoluteUri As Uri = xmlResolver.ResolveUri(baseUri, relativeUri)
If Not (absoluteUri Is Nothing) Then
Console.WriteLine(vbLf + "Resolved 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")
End If
Return absoluteUri
End Function
End Class
Remarks
The XmlDsigXPathTransform class allows you to address an XML document using the XPath language. This class uses an XPath expression to select the XML nodes you want to sign or encrypt while removing all others from either cryptographic operation.
Use the XmlDsigXPathTransform class to sign or encrypt specific parts of an XML document using an XPath expression. For information on initializing the XmlDsigXPathTransform class to the value of an XPath transform string, see the LoadInnerXml method.
The Uniform Resource Identifier (URI) that describes the XmlDsigXPathTransform class is defined by the XmlDsigXPathTransformUrl field.
For more information about the XPath transform, see Section 6.6.3 of the W3C XMLDSIG specification.
Constructors
| XmlDsigXPathTransform() |
Initializes a new instance of the XmlDsigXPathTransform class. |
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) |
| InputTypes |
Gets an array of types that are valid inputs to the LoadInput(Object) method of the current XmlDsigXPathTransform object. |
| OutputTypes |
Gets an array of types that are possible outputs from the GetOutput() methods of the current XmlDsigXPathTransform 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) |
When overridden in a derived class, returns the digest associated with a Transform object. (Inherited from Transform) |
| GetHashCode() |
Serves as the default hash function. (Inherited from Object) |
| GetInnerXml() |
Returns an XML representation of the parameters of a XmlDsigXPathTransform object that are suitable to be included as subelements of an XMLDSIG |
| GetOutput() |
Returns the output of the current XmlDsigXPathTransform object. |
| GetOutput(Type) |
Returns the output of the current XmlDsigXPathTransform object of type XmlNodeList. |
| 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 |
| LoadInput(Object) |
Loads the specified input into the current XmlDsigXPathTransform 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) |
Applies to
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