EncryptedXml.XmlEncElementUrl Field

public: System::String ^ XmlEncElementUrl;

public const string XmlEncElementUrl;

val mutable XmlEncElementUrl : string

Public Const XmlEncElementUrl As String 

Field Value

Examples

The following code example demonstrates how to encrypt an XML document using a symmetric key. This example does not include any key information in the encrypted XML document.

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

class Program
{
 static void Main(string[] args)
 {

 // Create an XmlDocument object.
 XmlDocument xmlDoc = new XmlDocument();

 // Load an XML file into the XmlDocument object.
 try
 {
 xmlDoc.PreserveWhitespace = true;
 xmlDoc.Load("test.xml");
 }
 catch (Exception e)
 {
 Console.WriteLine(e.Message);
 return;
 }

 // Create a new TripleDES key.
 TripleDESCryptoServiceProvider tDESkey = new TripleDESCryptoServiceProvider();

 try
 {
 // Encrypt the "creditcard" element.
 Encrypt(xmlDoc, "creditcard", tDESkey);

 // Display the encrypted XML to the console.
 Console.WriteLine("Encrypted XML:");
 Console.WriteLine();
 Console.WriteLine(xmlDoc.OuterXml);

 // Decrypt the "creditcard" element.
 Decrypt(xmlDoc, tDESkey);

 // Display the encrypted XML to the console.
 Console.WriteLine();
 Console.WriteLine("Decrypted XML:");
 Console.WriteLine();
 Console.WriteLine(xmlDoc.OuterXml);
 }
 catch (Exception e)
 {
 Console.WriteLine(e.Message);
 }
 finally
 {
 // Clear the TripleDES key.
 tDESkey.Clear();
 }
 }

 public static void Encrypt(XmlDocument Doc, string ElementToEncrypt, SymmetricAlgorithm Alg)
 {
 // Check the arguments.
 if (Doc == null)
 throw new ArgumentNullException("Doc");
 if (ElementToEncrypt == null)
 throw new ArgumentNullException("ElementToEncrypt");
 if (Alg == null)
 throw new ArgumentNullException("Alg");

 ////////////////////////////////////////////////
 // Find the specified element in the XmlDocument
 // object and create a new XmlElemnt object.
 ////////////////////////////////////////////////

 XmlElement elementToEncrypt = Doc.GetElementsByTagName(ElementToEncrypt)[0] as XmlElement;

 // Throw an XmlException if the element was not found.
 if (elementToEncrypt == null)
 {
 throw new XmlException("The specified element was not found");
 }

 //////////////////////////////////////////////////
 // Create a new instance of the EncryptedXml class
 // and use it to encrypt the XmlElement with the
 // symmetric key.
 //////////////////////////////////////////////////

 EncryptedXml eXml = new EncryptedXml();

 byte[] encryptedElement = eXml.EncryptData(elementToEncrypt, Alg, false);

 ////////////////////////////////////////////////
 // Construct an EncryptedData object and populate
 // it with the desired encryption information.
 ////////////////////////////////////////////////

 EncryptedData edElement = new EncryptedData();
 edElement.Type = EncryptedXml.XmlEncElementUrl;

 // Create an EncryptionMethod element so that the
 // receiver knows which algorithm to use for decryption.
 // Determine what kind of algorithm is being used and
 // supply the appropriate URL to the EncryptionMethod element.

 string encryptionMethod = null;

 if (Alg is TripleDES)
 {
 encryptionMethod = EncryptedXml.XmlEncTripleDESUrl;
 }
 else if (Alg is DES)
 {
 encryptionMethod = EncryptedXml.XmlEncDESUrl;
 }
 else if (Alg is Aes)
 {
 switch (Alg.KeySize)
 {
 case 128:
 encryptionMethod = EncryptedXml.XmlEncAES128Url;
 break;
 case 192:
 encryptionMethod = EncryptedXml.XmlEncAES192Url;
 break;
 case 256:
 encryptionMethod = EncryptedXml.XmlEncAES256Url;
 break;
 }
 }
 else
 {
 // Throw an exception if the transform is not in the previous categories
 throw new CryptographicException("The specified algorithm is not supported for XML Encryption.");
 }

 edElement.EncryptionMethod = new EncryptionMethod(encryptionMethod);

 // Add the encrypted element data to the
 // EncryptedData object.
 edElement.CipherData.CipherValue = encryptedElement;

 ////////////////////////////////////////////////////
 // Replace the element from the original XmlDocument
 // object with the EncryptedData element.
 ////////////////////////////////////////////////////

 EncryptedXml.ReplaceElement(elementToEncrypt, edElement, false);
 }

 public static void Decrypt(XmlDocument Doc, SymmetricAlgorithm Alg)
 {
 // Check the arguments.
 if (Doc == null)
 throw new ArgumentNullException("Doc");
 if (Alg == null)
 throw new ArgumentNullException("Alg");

 // Find the EncryptedData element in the XmlDocument.
 XmlElement encryptedElement = Doc.GetElementsByTagName("EncryptedData")[0] as XmlElement;

 // If the EncryptedData element was not found, throw an exception.
 if (encryptedElement == null)
 {
 throw new XmlException("The EncryptedData element was not found.");
 }

 // Create an EncryptedData object and populate it.
 EncryptedData edElement = new EncryptedData();
 edElement.LoadXml(encryptedElement);

 // Create a new EncryptedXml object.
 EncryptedXml exml = new EncryptedXml();

 // Decrypt the element using the symmetric key.
 byte[] rgbOutput = exml.DecryptData(edElement, Alg);

 // Replace the encryptedData element with the plaintext XML element.
 exml.ReplaceData(encryptedElement, rgbOutput);
 }
}

Imports System.Xml
Imports System.Security.Cryptography
Imports System.Security.Cryptography.Xml



Module Program

 Sub Main(ByVal args() As String)

 ' Create an XmlDocument object.
 Dim xmlDoc As New XmlDocument()

 ' Load an XML file into the XmlDocument object.
 Try
 xmlDoc.PreserveWhitespace = True
 xmlDoc.Load("test.xml")
 Catch e As Exception
 Console.WriteLine(e.Message)
 Return
 End Try

 ' Create a new TripleDES key. 
 Dim tDESkey As New TripleDESCryptoServiceProvider()


 Try
 ' Encrypt the "creditcard" element.
 Encrypt(xmlDoc, "creditcard", tDESkey)

 ' Display the encrypted XML to the console.
 Console.WriteLine("Encrypted XML:")
 Console.WriteLine()
 Console.WriteLine(xmlDoc.OuterXml)

 ' Decrypt the "creditcard" element.
 Decrypt(xmlDoc, tDESkey)

 ' Display the encrypted XML to the console.
 Console.WriteLine()
 Console.WriteLine("Decrypted XML:")
 Console.WriteLine()
 Console.WriteLine(xmlDoc.OuterXml)
 Catch e As Exception
 Console.WriteLine(e.Message)
 Finally
 ' Clear the TripleDES key.
 tDESkey.Clear()
 End Try

 End Sub


 Sub Encrypt(ByVal Doc As XmlDocument, ByVal ElementToEncrypt As String, ByVal Alg As SymmetricAlgorithm)
 ' Check the arguments. 
 If Doc Is Nothing Then
 Throw New ArgumentNullException("Doc")
 End If
 If ElementToEncrypt Is Nothing Then
 Throw New ArgumentNullException("ElementToEncrypt")
 End If
 If Alg Is Nothing Then
 Throw New ArgumentNullException("Alg")
 End If
 '''''''''''''''''''''''''''''''''''''''''''''''''''
 ' Find the specified element in the XmlDocument
 ' object and create a new XmlElemnt object.
 '''''''''''''''''''''''''''''''''''''''''''''''''''
 Dim elementEncrypt As XmlElement = Doc.GetElementsByTagName(ElementToEncrypt)(0)


 ' Throw an XmlException if the element was not found.
 If ElementToEncrypt Is Nothing Then
 Throw New XmlException("The specified element was not found")
 End If

 '''''''''''''''''''''''''''''''''''''''''''''''''''
 ' Create a new instance of the EncryptedXml class 
 ' and use it to encrypt the XmlElement with the 
 ' symmetric key.
 '''''''''''''''''''''''''''''''''''''''''''''''''''
 Dim eXml As New EncryptedXml()

 Dim encryptedElement As Byte() = eXml.EncryptData(elementEncrypt, Alg, False)

 '''''''''''''''''''''''''''''''''''''''''''''''''''
 ' Construct an EncryptedData object and populate
 ' it with the desired encryption information.
 '''''''''''''''''''''''''''''''''''''''''''''''''''

 Dim edElement As New EncryptedData()
 edElement.Type = EncryptedXml.XmlEncElementUrl

 ' Create an EncryptionMethod element so that the 
 ' receiver knows which algorithm to use for decryption.
 ' Determine what kind of algorithm is being used and
 ' supply the appropriate URL to the EncryptionMethod element.
 Dim encryptionMethod As String = Nothing

 If TypeOf Alg Is TripleDES Then
 encryptionMethod = EncryptedXml.XmlEncTripleDESUrl
 ElseIf TypeOf Alg Is DES Then
 encryptionMethod = EncryptedXml.XmlEncDESUrl
 ElseIf TypeOf Alg Is Aes Then
 Select Case Alg.KeySize
 Case 128
 encryptionMethod = EncryptedXml.XmlEncAES128Url
 Case 192
 encryptionMethod = EncryptedXml.XmlEncAES192Url
 Case 256
 encryptionMethod = EncryptedXml.XmlEncAES256Url
 End Select
 Else
 ' Throw an exception if the transform is not in the previous categories
 Throw New CryptographicException("The specified algorithm is not supported for XML Encryption.")
 End If

 edElement.EncryptionMethod = New EncryptionMethod(encryptionMethod)

 ' Add the encrypted element data to the 
 ' EncryptedData object.
 edElement.CipherData.CipherValue = encryptedElement

 '''''''''''''''''''''''''''''''''''''''''''''''''''
 ' Replace the element from the original XmlDocument
 ' object with the EncryptedData element.
 '''''''''''''''''''''''''''''''''''''''''''''''''''
 EncryptedXml.ReplaceElement(elementEncrypt, edElement, False)

 End Sub


 Sub Decrypt(ByVal Doc As XmlDocument, ByVal Alg As SymmetricAlgorithm)
 ' Check the arguments. 
 If Doc Is Nothing Then
 Throw New ArgumentNullException("Doc")
 End If
 If Alg Is Nothing Then
 Throw New ArgumentNullException("Alg")
 End If
 ' Find the EncryptedData element in the XmlDocument.
 Dim encryptedElement As XmlElement = Doc.GetElementsByTagName("EncryptedData")(0)

 ' If the EncryptedData element was not found, throw an exception.
 If encryptedElement Is Nothing Then
 Throw New XmlException("The EncryptedData element was not found.")
 End If

 ' Create an EncryptedData object and populate it.
 Dim edElement As New EncryptedData()
 edElement.LoadXml(encryptedElement)

 ' Create a new EncryptedXml object.
 Dim exml As New EncryptedXml()

 ' Decrypt the element using the symmetric key.
 Dim rgbOutput As Byte() = exml.DecryptData(edElement, Alg)

 ' Replace the encryptedData element with the plaintext XML element.
 exml.ReplaceData(encryptedElement, rgbOutput)

 End Sub
End Module

Remarks

The value of the XmlEncElementUrl field is http://www.w3.org/(2001/04/xmlenc#Element).