KeyInfo Class

//
// This example signs a file specified by a URI 
// using a detached signature. It then verifies  
// the signed XML.
//

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



class XMLDSIGDetached
{

    [STAThread]
    static void Main(string[] args)
    {
    // The URI to sign.
        string resourceToSign = "http://www.microsoft.com";

        // The name of the file to which to save the XML signature.
        string XmlFileName = "xmldsig.xml";

        try
        {

            // Generate a signing key.
            RSACryptoServiceProvider Key = new RSACryptoServiceProvider();

            Console.WriteLine("Signing: {0}", resourceToSign);

            // Sign the detached resourceand save the signature in an XML file.
            SignDetachedResource(resourceToSign, XmlFileName, Key);

            Console.WriteLine("XML signature was succesfully computed and saved to {0}.", XmlFileName);

            // Verify the signature of the signed XML.
            Console.WriteLine("Verifying signature...");

            //Verify the XML signature in the XML file.
            bool result = VerifyDetachedSignature(XmlFileName);

            // 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 SignDetachedResource(string URIString, string XmlSigFileName, RSA Key)
    {
        // Create a SignedXml object.
        SignedXml signedXml = new SignedXml();

        // Assign the key to the SignedXml object.
        signedXml.SigningKey = Key;

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

        // Add the passed URI to the reference object.
        reference.Uri = URIString;

        // 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();

        // Save the signed XML document to a file specified
        // using the passed string.
        XmlTextWriter xmltw = new XmlTextWriter(XmlSigFileName, new UTF8Encoding(false));
        xmlDigitalSignature.WriteTo(xmltw);
        xmltw.Close();
    }
    // Verify the signature of an XML file and return the result.
    public static Boolean VerifyDetachedSignature(string XmlSigFileName)
    {	
        // Create a new XML document.
        XmlDocument xmlDocument = new XmlDocument();

        // Load the passed XML file into the document.
        xmlDocument.Load(XmlSigFileName);

        // Create a new SignedXMl object.
        SignedXml signedXml = new SignedXml();

        // 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();
    }
}

//
// 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.
            RSACryptoServiceProvider Key = new RSACryptoServiceProvider();

            // 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;

        // 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, "", "MyElement", "samples");

        // Add some text to the node.
        node.InnerText = "Example text to be signed.";

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

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

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


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

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

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

            // 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 RSA key.
            rsaKey.Clear();
        }

    }

    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);

        // 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.
        ek.KeyInfo.AddClause(kin);

        // 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.
        exml.DecryptDocument();

    }

}

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, "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, "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, 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 
        // 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);

        // Set the KeyInfo element to specify the
        // name of a 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.
        edElement.KeyInfo.AddClause(kin);

        // 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, 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.
        exml.DecryptDocument();

    }


}