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EncryptionPropertyCollection.Add Method

Adds an EncryptionProperty object to the EncryptionPropertyCollection object.

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

public int Add(
	EncryptionProperty value

Return Value

Type: System.Int32
The position at which the new element is inserted.

The following code example encrypts and decrypts an XML document. This code example creates an EncryptionProperty object that contains custom information about the EncryptedKey element, and adds the EncryptionProperty object to the EncryptionPropertyCollection collection of the EncryptedXml class. Finally, this code example displays information about the EncryptionProperty object and the EncryptionPropertyCollection collection.

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. 
            xmlDoc.PreserveWhitespace = true;
        catch (Exception e)

        // Create a new RSA key.  This key will encrypt a symmetric key, 
        // which will then be imbedded in the XML document.  
        RSA rsaKey = new RSACryptoServiceProvider();

            // Encrypt the "creditcard" element.
            Encrypt(xmlDoc, "creditcard", rsaKey, "rsaKey");

            // Inspect the EncryptedKey element.

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

        catch (Exception e)
            // Clear the RSA key.


    public static void Encrypt(XmlDocument Doc, string ElementToEncrypt, RSA Alg, string KeyName)
        // 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  
        // a new random symmetric key. 

        // Create a 256 bit Rijndael key.
        RijndaelManaged sessionKey = new RijndaelManaged();
        sessionKey.KeySize = 256;

        EncryptedXml eXml = new EncryptedXml();

        byte[] encryptedElement = eXml.EncryptData(elementToEncrypt, sessionKey, 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.

        edElement.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncAES256Url);

        // Encrypt the session key and add it to an EncryptedKey element.
        EncryptedKey ek = new EncryptedKey();

        byte[] encryptedKey = EncryptedXml.EncryptKey(sessionKey.Key, Alg, false);

        ek.CipherData = new CipherData(encryptedKey);

        ek.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncRSA15Url);

        // Save some more information about the key using 
        // the EncryptionProperty element.  In this example, 
        // we will save the value "LibVersion1".  You can save
        // anything you want here. 

        // Create a new "EncryptionProperty" XmlElement object. 
        XmlElement element =  new XmlDocument().CreateElement("EncryptionProperty", EncryptedXml.XmlEncNamespaceUrl);

        // Set the value of the EncryptionProperty" XmlElement object.
        element.InnerText = "LibVersion1";

        // Create the EncryptionProperty object using the XmlElement object. 
        EncryptionProperty encProp = new EncryptionProperty(element);

        // Add the EncryptionProperty object to the EncryptedData object.

        // Set the KeyInfo element to specify the 
        // name of the RSA key. 

        // Create a new KeyInfo element.
        edElement.KeyInfo = new KeyInfo();

        // Create a new KeyInfoName element.
        KeyInfoName kin = new KeyInfoName();

        // Specify a name for the key.
        kin.Value = KeyName;

        // Add the KeyInfoName element to the  
        // EncryptedKey object.

        // Add the encrypted key to the  
        // EncryptedData object.

        edElement.KeyInfo.AddClause(new KeyInfoEncryptedKey(ek));

        // 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, RSA Alg, string KeyName)
        // Check the arguments.   
        if (Doc == null)
            throw new ArgumentNullException("Doc");
        if (Alg == null)
            throw new ArgumentNullException("Alg");
        if (KeyName == null)
            throw new ArgumentNullException("KeyName");

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

        // Add a key-name mapping. 
        // This method can only decrypt documents 
        // that present the specified key name.
        exml.AddKeyNameMapping(KeyName, Alg);

        // Decrypt the element.


    static void InspectElement(XmlDocument Doc)
        // Get the EncryptedData element from the XMLDocument object.
        XmlElement encryptedData = Doc.GetElementsByTagName("EncryptedData")[0] as XmlElement;

        // Create a new EncryptedData object.
        EncryptedData encData = new EncryptedData();

        // Load the XML from the document to 
        // initialize the EncryptedData object.

        // Display the properties. 
        // Most values are Null by default.

        Console.WriteLine("EncryptedData.CipherData: " + encData.CipherData.GetXml().InnerXml);
        Console.WriteLine("EncryptedData.Encoding: " + encData.Encoding);
        Console.WriteLine("EncryptedData.EncryptionMethod: " + encData.EncryptionMethod.GetXml().InnerXml);

        EncryptionPropertyCollection encPropCollection = encData.EncryptionProperties;

        Console.WriteLine("Number of elements in the EncryptionPropertyCollection: " + encPropCollection.Count);

        foreach(EncryptionProperty encProp in encPropCollection)
                Console.WriteLine("EncryptionProperty.ID: " + encProp.Id);
                Console.WriteLine("EncryptionProperty.PropertyElement: " + encProp.PropertyElement.InnerXml);
                Console.WriteLine("EncryptionProperty.Target: " + encProp.Target);


        Console.WriteLine("EncryptedData.Id: " + encData.Id);
        Console.WriteLine("EncryptedData.KeyInfo: " + encData.KeyInfo.GetXml().InnerXml);
        Console.WriteLine("EncryptedData.MimeType: " + encData.MimeType);


.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
© 2015 Microsoft