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

namespace EncryptDecrypt
{
  public class EDclass
  {
      public static void EncryptFile(string sInputFilename, string sOutputFilename, string sKey)
      {
          FileStream fsEncrypted = new FileStream(sInputFilename, FileMode.Create, FileAccess.ReadWrite);

          DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
          DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
          DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
          ICryptoTransform desencrypt = DES.CreateEncryptor();
          CryptoStream cryptostream = new CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write);

          byte[] bytearrayinput = new byte[fsEncrypted.Length];
          fsEncrypted.Read(bytearrayinput, 0, bytearrayinput.Length);
          cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);
          cryptostream.Close();
          fsEncrypted.Close();
      }

    public static void DecryptFile(string sInputFilename, string sOutputFilename, string sKey)
    {
      DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
      DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
      DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);

      FileStream fsread = new FileStream(sInputFilename, FileMode.Open, FileAccess.Read);
      ICryptoTransform desdecrypt = DES.CreateDecryptor();

      CryptoStream cryptostreamDecr = new CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read);
      StreamWriter fsDecrypted = new StreamWriter(sOutputFilename);
      fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
      fsDecrypted.Flush();
      fsDecrypted.Close();
    } 
  }
}