Illustrates encrypting a file : File Cryptography : File Stream C# Source Code

    

/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy

Publisher: Sybex;
ISBN: 0782129110
*/

/*
  Example19_9.cs illustrates encrypting a file
*/

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();

    }

}