This documentation is archived and is not being maintained.

EncryptionMethod Class

Encapsulates the encryption algorithm used for XML encryption.

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

public class EncryptionMethod
public class EncryptionMethod
public class EncryptionMethod
Not applicable.

The <EncryptionMethod> tag uses a Uniform Resource Identifier (URI) to identify the encryption algorithm that must be used to decrypt XML data. The EncryptionMethod class encapsulates the <EncryptionMethod> tag defined by the World Wide Web Consortium XML Encryption specification located at http://www.w3.org/TR/xmlenc-core/.

Use the EncryptionMethod class to identify the encryption algorithm associated with the EncryptedData element or the EncryptedKey element.

Use one of the URI identifiers defined by the World Wide Web Consortium XML Encryption specification located at http://www.w3.org/TR/xmlenc-core/. All URI identifiers are accessible as static fields of the EncryptedXml class.

The following code example demonstrates how to create a simple utility class that uses the TripleDES algorithm to encrypt an 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();

			// Create a new instance of the TrippleDESDocumentEncryption object
			// defined in this sample.
			TrippleDESDocumentEncryption xmlTDES = new TrippleDESDocumentEncryption(xmlDoc, tDESkey);
			
			try
			{
				// Encrypt the "creditcard" element.
				xmlTDES.Encrypt("creditcard");

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

				// Decrypt the "creditcard" element.
				xmlTDES.Decrypt();

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

		}

	}

class TrippleDESDocumentEncryption
{
	protected XmlDocument docValue;
	protected TripleDES algValue;

	public TrippleDESDocumentEncryption(XmlDocument Doc, TripleDES Key)
	{
		if (Doc != null)
		{
			docValue = Doc;
		}
		else
		{
			throw new ArgumentNullException("Doc");
		}

		if (Key != null)
		{

			algValue = Key;
		}
		else
		{
			throw new ArgumentNullException("Key");
		}
	}

	public XmlDocument Doc { set { docValue = value; } get { return docValue; } }
	public TripleDES Alg { set { algValue = value; } get { return algValue; } }

	public void Clear()
	{
		if (algValue != null)
		{
			algValue.Clear();
		}
		else
		{
			throw new Exception("No TripleDES key was found to clear.");
		}
	}

	public void Encrypt(string Element)
	{
		// Find the element by name and create a new
		// XmlElement object.
		XmlElement inputElement = docValue.GetElementsByTagName(Element)[0] as XmlElement;

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

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

		// Encrypt the element using the symmetric key.
		byte[] rgbOutput = exml.EncryptData(inputElement, algValue, false);

		// Create an EncryptedData object and populate it.
		EncryptedData ed = new EncryptedData();

		// Specify the namespace URI for XML encryption elements.
		ed.Type = EncryptedXml.XmlEncElementUrl;

		// Specify the namespace URI for the TrippleDES algorithm.
		ed.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncTripleDESUrl);

		// Create a CipherData element.
		ed.CipherData = new CipherData();

		// Set the CipherData element to the value of the encrypted XML element.
		ed.CipherData.CipherValue = rgbOutput;

		// Replace the plaintext XML elemnt with an EncryptedData element.
		EncryptedXml.ReplaceElement(inputElement, ed, false);
	}

	public void Decrypt()
	{

		// XmlElement object.
		XmlElement encryptedElement = docValue.GetElementsByTagName("EncryptedData")[0] as XmlElement;

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

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

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

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

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

	}

}

import System.*;
import System.Xml.*;
import System.Security.Cryptography.*;
import System.Security.Cryptography.Xml.*;

class Program
{
    public static void main(String[] args) throws Exception
    {
        // Create an XmlDocument object.
        XmlDocument xmlDoc = new XmlDocument();

        // Load an XML file into the XmlDocument object.
        try {
            xmlDoc.set_PreserveWhitespace(true);
            xmlDoc.Load("test.xml");
        }
        catch (System.Exception e) {
            Console.WriteLine(e.get_Message());
            return;
        }
        // Create a new TripleDES key. 
        TripleDESCryptoServiceProvider tDESkey = 
            new TripleDESCryptoServiceProvider();
        // Create a new instance of the TrippleDESDocumentEncryption object
        // defined in this sample.
        TrippleDESDocumentEncryption xmlTDES = 
            new TrippleDESDocumentEncryption(xmlDoc, tDESkey);

        try {
            // Encrypt the "creditcard" element.
            xmlTDES.Encrypt("creditcard");
            // Display the encrypted XML to the console.
            Console.WriteLine("Encrypted XML:");
            Console.WriteLine();
            Console.WriteLine(xmlTDES.get_Doc().get_OuterXml());
            // Decrypt the "creditcard" element.
            xmlTDES.Decrypt();
            // Display the encrypted XML to the console.
            Console.WriteLine();
            Console.WriteLine("Decrypted XML:");
            Console.WriteLine();
            Console.WriteLine(xmlTDES.get_Doc().get_OuterXml());
        }
        catch (System.Exception e) {
            Console.WriteLine(e.get_Message());
        }
        finally {
            // Clear the TripleDES key.
            xmlTDES.Clear();
        }
    } //main
} //Program

class TrippleDESDocumentEncryption
{
    protected XmlDocument docValue;
    protected TripleDES algValue;

    public TrippleDESDocumentEncryption(XmlDocument doc, TripleDES key)
    {
        if (doc != null) {
            docValue = doc;
        }
        else {
            throw new ArgumentNullException("doc");
        }

        if (key != null) {
            algValue = key;
        }
        else {
            throw new ArgumentNullException("key");
        }
    } //TrippleDESDocumentEncryption

    /** @property 
     */
    public XmlDocument get_Doc()
    {
        return docValue;
    } //get_Doc

    /** @property 
     */
    public void set_Doc(XmlDocument value)
    {
        docValue = value;
    } //set_Doc

    /** @property 
     */
    public TripleDES get_Alg()
    {
        return algValue;
    } //get_Alg

    /** @property 
     */
    public void set_Alg(TripleDES value)
    {
        algValue = value;
    } //set_Alg

    public void Clear() throws Exception
    {
        if (algValue != null) {
            algValue.Clear();
        }
        else {
            throw new Exception("No TripleDES key was found to clear.");
        }
    } //Clear

    public void Encrypt(String element) throws Exception
    {
        // Find the element by name and create a new
        // XmlElement object.
        XmlElement inputElement = (XmlElement)docValue.GetElementsByTagName(
            element).get_ItemOf(0);

        // If the element was not found, throw an exception.
        if (inputElement == null) {
            throw new Exception("The element was not found.");
        }
        // Create a new EncryptedXml object.
        EncryptedXml eXml = new EncryptedXml(docValue);

        // Encrypt the element using the symmetric key.
        ubyte rgbOutput[] = eXml.EncryptData(inputElement, algValue, false);

        // Create an EncryptedData object and populate it.
        EncryptedData ed = new EncryptedData();

        // Specify the namespace URI for XML encryption elements.
        ed.set_Type(EncryptedXml.XmlEncElementUrl);

        // Specify the namespace URI for the TrippleDES algorithm.
        ed.set_EncryptionMethod(new EncryptionMethod(EncryptedXml.
            XmlEncTripleDESUrl));

        // Create a CipherData element.
        ed.set_CipherData(new CipherData());

        // Set the CipherData element to the value of the encrypted XML element.
        ed.get_CipherData().set_CipherValue(rgbOutput);

        // Replace the plaintext XML elemnt with an EncryptedData element.
        EncryptedXml.ReplaceElement(inputElement, ed, false);
    } //Encrypt

    public void Decrypt() throws Exception
    {
        // XmlElement object.
        XmlElement encryptedElement = (XmlElement)docValue.
            GetElementsByTagName("EncryptedData").get_ItemOf(0);

        // If the EncryptedData element was not found, throw an exception.
        if (encryptedElement == null) {
            throw new Exception("The EncryptedData element was not found.");
        }
        // Create an EncryptedData object and populate it.
        EncryptedData ed = new EncryptedData();
        ed.LoadXml(encryptedElement); 

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

        // Decrypt the element using the symmetric key.
        ubyte rgbOutput[] = eXml.DecryptData(ed, algValue);

        // Replace the encryptedData element with the plaintext XML elemnt.
        eXml.ReplaceData(encryptedElement, rgbOutput);
    } //Decrypt 
} //TrippleDESDocumentEncryption

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 Rijndael)
        {
            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);

    }


}

import System.*;
import System.Xml.*;
import System.Security.Cryptography.*;
import System.Security.Cryptography.Xml.*;

class Program
{
    public static void main(String[] args)
    {
        // Create an XmlDocument object.
        XmlDocument xmlDoc = new XmlDocument();
        // Load an XML file into the XmlDocument object.
        try {
            xmlDoc.set_PreserveWhitespace(true);
            xmlDoc.Load("test.xml");
        }
        catch (System.Exception e) {
            Console.WriteLine(e.get_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.get_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.get_OuterXml());
        }
        catch (System.Exception e) {
            Console.WriteLine(e.get_Message());
        }
        finally {
            // Clear the TripleDES key.
            tDESkey.Clear();
        }
    } //main

    public static void Encrypt(XmlDocument doc, String elementToEncrypt,
        SymmetricAlgorithm alg) throws XmlException,CryptographicException
    {
        // 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 elementToEncrypt1 = (XmlElement)doc.GetElementsByTagName(
            elementToEncrypt).get_ItemOf(0);

        // Throw an XmlException if the element was not found.
        if (elementToEncrypt1 == 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();

        ubyte encryptedElement[] = eXml.EncryptData(elementToEncrypt1, alg,
            false);
        ////////////////////////////////////////////////
        // Construct an EncryptedData object and populate
        // it with the desired encryption information.
        ////////////////////////////////////////////////
        EncryptedData edElement = new EncryptedData();
        edElement.set_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 instanceof TripleDES) {
            encryptionMethod = EncryptedXml.XmlEncTripleDESUrl;
        }
        else {
            if (alg instanceof DES) {
                encryptionMethod = EncryptedXml.XmlEncDESUrl;
            }
            else {
                if (alg instanceof Rijndael) {
                    switch (alg.get_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.set_EncryptionMethod(new EncryptionMethod(encryptionMethod));

        // Add the encrypted element data to the 
        // EncryptedData object.
        edElement.get_CipherData().set_CipherValue(encryptedElement);

        ////////////////////////////////////////////////////
        // Replace the element from the original XmlDocument
        // object with the EncryptedData element.
        ////////////////////////////////////////////////////
        EncryptedXml.ReplaceElement(elementToEncrypt1, edElement, false);
    } //Encrypt

    public static void Decrypt(XmlDocument doc, SymmetricAlgorithm alg) 
        throws XmlException
    {
        // 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 = (XmlElement)doc.GetElementsByTagName(
            "EncryptedData").get_ItemOf(0);

        // 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.
        ubyte rgbOutput[] = eXml.DecryptData(edElement, alg);
        // Replace the encryptedData element with the plaintext XML element.
        eXml.ReplaceData(encryptedElement, rgbOutput);
    } //Decrypt 
} //Program

System.Object
  System.Security.Cryptography.Xml.EncryptionMethod

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

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0
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