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

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

class App
{
   static void Main()
   {
      Rijndael r = Rijndael.Create();
      r.Mode = CipherMode.ECB;
      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);
      Console.WriteLine(BitConverter.ToString(input));
      ICryptoTransform de = r.CreateDecryptor();
      byte[] output = CryptoTransform(input, de);
      Console.WriteLine(Encoding.ASCII.GetString(output));
   }
   static byte[] CryptoTransform(byte[] input, ICryptoTransform en)
   {
      byte[] output = new byte[input.Length * 2];
      int inputOffset = 0;
      int bytesToRead = en.InputBlockSize;
      int outputOffset = 0;
      int totalBytesTransformed = 0;

      while (true)
      {
         int numTransformed = en.TransformBlock(input, inputOffset, bytesToRead, output, outputOffset);
         inputOffset += bytesToRead;
         outputOffset += numTransformed;
         totalBytesTransformed += numTransformed;
         if (input.Length - inputOffset < en.InputBlockSize)
            break;
      }
      byte[] tempBuffer = en.TransformFinalBlock(input, inputOffset, input.Length - inputOffset);
      byte[] returnedBuffer = new byte[totalBytesTransformed + tempBuffer.Length];
      Array.Copy(output, 0, returnedBuffer, 0, totalBytesTransformed);
      Array.Copy(tempBuffer, 0, returnedBuffer, totalBytesTransformed, tempBuffer.Length);
      return returnedBuffer;
   }
}