using System;
using System.IO;
using System.Security.Cryptography;
  
public class Example19_9
{
  public static void Main()
  {
  
    // Create a new file to work with
    FileStream fsOut = File.Create(@"c:\temp\encrypted.txt");
  
    // Create a new crypto provider
    TripleDESCryptoServiceProvider tdes =
      new TripleDESCryptoServiceProvider();
  
    // Create a cryptostream to encrypt to the filestream
    CryptoStream cs = new CryptoStream(fsOut, tdes.CreateEncryptor(),
      CryptoStreamMode.Write);
  
    // Create a StreamWriter to format the output
    StreamWriter sw = new StreamWriter(cs);
  
    // And write some data
    sw.WriteLine("'Twas brillig, and the slithy toves");
    sw.WriteLine("Did gyre and gimble in the wabe.");
    sw.Flush();
    sw.Close();
  
    // save the key and IV for future use
    FileStream fsKeyOut = File.Create(@"c:\\temp\encrypted.key");
  
    // use a BinaryWriter to write formatted data to the file
    BinaryWriter bw = new BinaryWriter(fsKeyOut);
  
    // write data to the file
    bw.Write( tdes.Key );
    bw.Write( tdes.IV );
  
    // flush and close
    bw.Flush();
    bw.Close();
  
  }
  
}

using System;
using System.IO;
using System.Security.Cryptography;
  
public class Example19_10
{
  public static void Main()
  {
  
    // Create a new crypto provider
    TripleDESCryptoServiceProvider tdes =
      new TripleDESCryptoServiceProvider();
  
    // open the file containing the key and IV
    FileStream fsKeyIn = File.OpenRead(@"c:\temp\encrypted.key");
  
    // use a BinaryReader to read formatted data from the file
    BinaryReader br = new BinaryReader(fsKeyIn);
  
    // read data from the file and close it
    tdes.Key = br.ReadBytes(24);
    tdes.IV = br.ReadBytes(8);
  
    // Open the encrypted file
    FileStream fsIn = File.OpenRead(@"c:\\temp\\encrypted.txt");
  
    // Create a cryptostream to decrypt from the filestream
    CryptoStream cs = new CryptoStream(fsIn, tdes.CreateDecryptor(),
      CryptoStreamMode.Read);
  
    // Create a StreamReader to format the input
    StreamReader sr = new StreamReader(cs);
  
    // And decrypt the data
    Console.WriteLine(sr.ReadToEnd());
    sr.Close();
  
  }
  
}