Central Key Management

using System;
using System.Diagnostics;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography;

namespace TestClient
{
    public partial class Form1 : Form
    {
        RijndaelManaged _sessionKey = null;
        public Form1()
        {
            InitializeComponent();
        }

        private void buttonGetKey_Click(object sender, EventArgs e)
        {
            X509Certificate2 certificate = comboBoxCertificates.SelectedItem as X509Certificate2;

            if (certificate == null)
                throw new ApplicationException("Certificate not selected");

            int keyId;
            if (Int32.TryParse(textBoxKeyId.Text, out keyId) == false || keyId <= 0)
                throw new ApplicationException("Invalid KeyId specified");

            Stopwatch sw = new Stopwatch();
            sw.Start();
            
            KeyManager.Service svc = new TestClient.KeyManager.Service();

            KeyManager.SessionKeyInfo keyInfo = svc.GetSessionKey(keyId, certificate.Export(X509ContentType.SerializedCert));

            System.IO.MemoryStream stream = new System.IO.MemoryStream();
            System.Xml.XmlTextWriter writer = new System.Xml.XmlTextWriter(stream, Encoding.UTF8);
            keyInfo.WrappedKey.WriteTo(writer);
            writer.Flush();

            stream.Position = 0;
            Core.Cryptography.WrappedData wrappedData = new Core.Cryptography.WrappedData();
            System.Xml.XmlTextReader reader = new System.Xml.XmlTextReader(stream);
            wrappedData.ReadXml(reader);

            string clearKey = Core.Cryptography.CryptHelper.AsymmetricDecrypt(wrappedData);
            _sessionKey = Core.Cryptography.CryptHelper.GetSessionKey(clearKey);
            sw.Stop();

            toolStripStatusLabel1.Text = string.Format("GetKey took {0} ms", sw.ElapsedMilliseconds);

            buttonDecrypt.Enabled = true;
            buttonEncrypt.Enabled = true;
        }

        private void buttonCreate_Click(object sender, EventArgs e)
        {

            X509Certificate2 certificate = comboBoxCertificates.SelectedItem as X509Certificate2;

            if (certificate == null)
                throw new ApplicationException("Certificate not selected");

            Stopwatch sw = new Stopwatch();
            sw.Start();
            KeyManager.Service svc = new TestClient.KeyManager.Service();
            KeyManager.SessionKeyInfo keyInfo = svc.CreateSessionKey(certificate.Export(X509ContentType.SerializedCert));

            textBoxKeyId.Text = keyInfo.KeyId.ToString();

            System.IO.MemoryStream stream = new System.IO.MemoryStream();
            System.Xml.XmlTextWriter writer = new System.Xml.XmlTextWriter(stream, Encoding.UTF8);
            keyInfo.WrappedKey.WriteTo(writer);
            writer.Flush();

            stream.Position = 0;
            System.IO.StreamReader r = new System.IO.StreamReader(stream);
            string xml = r.ReadToEnd();

            Core.Cryptography.WrappedData wrappedData = new Core.Cryptography.WrappedData();
            stream.Position = 0;
            System.Xml.XmlTextReader reader = new System.Xml.XmlTextReader(stream);
            wrappedData.ReadXml(reader);

            string clearKey = Core.Cryptography.CryptHelper.AsymmetricDecrypt(wrappedData);
            _sessionKey = Core.Cryptography.CryptHelper.GetSessionKey(clearKey);
            sw.Stop();

            toolStripStatusLabel1.Text = string.Format( "Create Key took {0} ms", sw.ElapsedMilliseconds);

            buttonDecrypt.Enabled = true;
            buttonEncrypt.Enabled = true;


        }

        private void buttonEncrypt_Click(object sender, EventArgs e)
        {
            try
            {
                string clearText = textBoxOriginal.Text;
                byte[] clearData = Encoding.Unicode.GetBytes(clearText);

                Stopwatch sw = new Stopwatch();
                sw.Start();
                byte[] encryptedData = _sessionKey.CreateEncryptor().TransformFinalBlock(clearData, 0, clearData.Length);
                string ecryptedText = Convert.ToBase64String(encryptedData);
                textBoxEcrypted.Text = ecryptedText;
                sw.Stop();

                toolStripStatusLabel1.Text = string.Format("Encrypted Data in {0} ms", sw.ElapsedMilliseconds);
            }
            catch (System.Security.Cryptography.CryptographicException ex)
            {
                toolStripStatusLabel1.Text = ex.Message;
            }
        }

        private void buttonDecrypt_Click(object sender, EventArgs e)
        {
            try
            {
                string encryptedString = textBoxEcrypted.Text;
                byte[] encryptedData = Convert.FromBase64String(encryptedString);

                Stopwatch sw = new Stopwatch();
                sw.Start();
                byte[] clearData = _sessionKey.CreateDecryptor().TransformFinalBlock(encryptedData, 0, encryptedData.Length);
                string clearText = Encoding.Unicode.GetString(clearData);
                textBoxOriginal.Text = clearText;
                sw.Stop();

                toolStripStatusLabel1.Text = string.Format("Decrypted Data in {0} ms", sw.ElapsedMilliseconds);
            }
            catch (System.Security.Cryptography.CryptographicException ex)
            {
                toolStripStatusLabel1.Text = ex.Message;
            }

        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // Get the list of available certificates
            X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
            store.Open(OpenFlags.ReadOnly);

            foreach (X509Certificate2 certificate in store.Certificates)
            {
                if (certificate.HasPrivateKey == true)
                    comboBoxCertificates.Items.Add(certificate);
            }

            toolStripStatusLabel1.Text = "Select a certificate to start";           

        }

        private void comboBoxCertificates_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (comboBoxCertificates.SelectedItem != null)
            {
                buttonCreate.Enabled = true;
                buttonGetKey.Enabled = true;

                toolStripStatusLabel1.Text = string.Empty;
            }
            else
            {
                buttonCreate.Enabled = false;
                buttonGetKey.Enabled = false;
            }
        }
    }
}