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();    }  }