// (c) 2006 Richard Grimes
// www.grimes.demon.co.uk

using System;
using System.Security.Cryptography;
using System.Text;
using System.IO;

class App
{
   static void Main()
   {
      Rijndael r = Rijndael.Create();
      string phrase = "daisy, daisy, give me your answer to";
      PasswordDeriveBytes pdb = new PasswordDeriveBytes(phrase, new byte[0]);
      r.Key = pdb.GetBytes(r.KeySize >> 3);
      string data = "The quick brown fox jumps over the lazy dog.";
      ICryptoTransform en = r.CreateEncryptor();
      byte[] input = Encoding.ASCII.GetBytes(data);
      input = CryptoTransform(input, en, true);
      Console.WriteLine(Encoding.ASCII.GetString(input));
      ICryptoTransform de = r.CreateDecryptor();
      byte[] output = CryptoTransform(input, de, false);
      Console.WriteLine(Encoding.ASCII.GetString(output));
   }
   static byte[] CryptoTransform(byte[] input, ICryptoTransform en, bool bEncrypt)
   {
      MemoryStream sInput = new MemoryStream(input);
      MemoryStream sOutput = new MemoryStream();
      CryptoStream cs;
      if (bEncrypt)
      {
         cs = new CryptoStream(sOutput, new ToBase64Transform(), CryptoStreamMode.Write);
         cs = new CryptoStream(cs, en, CryptoStreamMode.Write);
      }
      else
      {
         cs = new CryptoStream(sOutput, en, CryptoStreamMode.Write);
         cs = new CryptoStream(cs, new FromBase64Transform(), CryptoStreamMode.Write);
      }
      byte[] buffer = new byte[1024];
      while (true)
      {
         int read = sInput.Read(buffer, 0, buffer.Length);
         if (read == 0) break;
         cs.Write(buffer, 0, read);
      }
      cs.FlushFinalBlock();
      cs.Clear();
      return sOutput.ToArray();
   }
}