using System;
using System.Security.Principal;
using System.Security.Permissions;
using System.Security.Cryptography;

namespace Demo
{
    class MainClass
    {
        /// <summary>
        /// DESCryptoServiceProvider
        /// </summary>
        public static void DESCryptoDemo ()
        {
            string message = "This message is security!";
            string strEncryp, strDecryp;

            DESCryptoServiceProvider des = new DESCryptoServiceProvider ();
            System.Text.Encoding encoding = new System.Text.UTF8Encoding ();

            byte[] key = encoding.GetBytes ("1a345689");
            byte[] iv = { 0, 91, 2, 3, 4, 5, 6, 7 };
            ICryptoTransform encryptor = des.CreateEncryptor (key, iv);
            ICryptoTransform decryptor = des.CreateDecryptor (key, iv);
            //all above 4 lines can be TiHuan as below
            des.GenerateKey ();
            des.GenerateIV ();
            encryptor = des.CreateEncryptor ();
            decryptor = des.CreateDecryptor ();
            {
                byte[] byteMessage = encoding.GetBytes (message);
                byte[] byteEncrypto = encryptor.TransformFinalBlock (byteMessage, 0, byteMessage.Length);
                strEncryp = Convert.ToBase64String (byteEncrypto);
            }
            {
                byte[] byteEncryto2 = Convert.FromBase64String (strEncryp);
                byte[] byteDecrypto = decryptor.TransformFinalBlock (byteEncryto2, 0, byteEncryto2.Length);
                strDecryp = encoding.GetString (byteDecrypto);
            }
            Console.WriteLine ("Message:" + message);
            Console.WriteLine ("Encrypted:" + strEncryp);
            Console.WriteLine ("Decrypted:" + strDecryp);
            Console.ReadKey ();
        }

        public static void Invoke (Action action)
        {
            try {
                action ();
            } catch (Exception ex) {
                Console.WriteLine (ex.Message);
            }
        }

        public static void Main (string[] args)
        {
            DESCryptoDemo ();
            Invoke (() => TestMethod1 ());
            Invoke (() => TestMethod2 ());
            Invoke (() => TestMethod3 ());
            Console.ReadKey ();
        }

        [PrincipalPermission (SecurityAction.Demand, Name = "Administrator")]
        public static void TestMethod1 ()
        {
            Console.WriteLine ("TestMethod1 successfully Executed!");
        }

        [PrincipalPermission (SecurityAction.Demand, Role = "Administrators")]
        public static void TestMethod2 ()
        {
            Console.WriteLine ("TestMethod2 successfully Executed!");
        }

        [PrincipalPermission (SecurityAction.Demand, Role = "Guests")]
        public static void TestMethod3 ()
        {
            Console.WriteLine ("TestMethod3 successfully Executed!");
        }
    }
}