64 Bit encryption in asp.net

Hi frienz,
2day i'm showing 64 bit encryption and decryption using a Key in asp.net.for that u need to import these name space's,

using System.Security.Cryptography;

using System.Text;

using System.IO;

Encryption

    private const string DEFAULT_KEY = "#kl?+@<z";

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

        {

        }

    }

    protected void txt_string_TextChanged(object sender, EventArgs e)

    {

        DESCryptoServiceProvider des = new DESCryptoServiceProvider();

        MemoryStream MemoryStream = new MemoryStream();

        CryptoStream Cryptostream;

        string key="#kl?+@<z";

        CheckKey(ref key);

        des.Key = HashKey(key, des.KeySize / 8);

        des.IV = HashKey(key, des.KeySize / 8);

        string stringToEncrypt = txt_string.Text.Trim();

        byte[] inputBytes = Encoding.UTF8.GetBytes(stringToEncrypt);

        Cryptostream = new CryptoStream(MemoryStream, des.CreateEncryptor(), CryptoStreamMode.Write);

        Cryptostream.Write(inputBytes, 0, inputBytes.Length);

        Cryptostream.FlushFinalBlock();

        string result = Convert.ToBase64String(MemoryStream.ToArray());

        Label1.Text = result.ToString();

       

    }

    private static void CheckKey(ref string keyToCheck)

    {

        keyToCheck = keyToCheck.Length > 8 ? keyToCheck.Substring(0, 8) : keyToCheck;

        if (keyToCheck.Length < 8)

        {

            for (int i = keyToCheck.Length; i < 8; i++)

            {

                keyToCheck += DEFAULT_KEY[i];

            }

        }

    }

    private static byte[] HashKey(string key, int length)

    {

        SHA1CryptoServiceProvider sha1 = new SHA1CryptoServiceProvider();

        // Hash the key

        byte[] keyBytes = Encoding.UTF8.GetBytes(key);

        byte[] hash = sha1.ComputeHash(keyBytes);

        // Truncate hash

        byte[] truncatedHash = new byte[length];

        Array.Copy(hash, 0, truncatedHash, 0, length);

        return truncatedHash;

    }

Decryption

private const string DEFAULT_KEY = "#kl?+@<z";

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

        {

        }

    }

    protected void txt_String_TextChanged(object sender, EventArgs e)

    {

        string key = "#kl?+@<z";

        string txt = txt_String.Text.Trim();

        DESCryptoServiceProvider des = new DESCryptoServiceProvider();

        MemoryStream memoryStream = new MemoryStream();

        CryptoStream cryptoStream;

        // Check whether the key is valid, otherwise make it valid

        CheckKey(ref key);

        des.Key = HashKey(key, des.KeySize / 8);

        des.IV = HashKey(key, des.KeySize / 8);

        byte[] inputBytes = Convert.FromBase64String(txt);

        cryptoStream = new CryptoStream(memoryStream, des.CreateDecryptor(), CryptoStreamMode.Write);

        cryptoStream.Write(inputBytes, 0, inputBytes.Length);

        cryptoStream.FlushFinalBlock();

        Encoding encoding = Encoding.UTF8;

        lbl.Text= encoding.GetString(memoryStream.ToArray());

    }

    private static void CheckKey(ref string keyToCheck)

    {

        keyToCheck = keyToCheck.Length > 8 ? keyToCheck.Substring(0, 8) : keyToCheck;

        if (keyToCheck.Length < 8)

        {

            for (int i = keyToCheck.Length; i < 8; i++)

            {

                keyToCheck += DEFAULT_KEY[i];

            }

        }

    }

    private static byte[] HashKey(string key, int length)

    {

        SHA1CryptoServiceProvider sha1 = new SHA1CryptoServiceProvider();

        // Hash the key

        byte[] keyBytes = Encoding.UTF8.GetBytes(key);

        byte[] hash = sha1.ComputeHash(keyBytes);

        // Truncate hash

        byte[] truncatedHash = new byte[length];

        Array.Copy(hash, 0, truncatedHash, 0, length);

        return truncatedHash;

    }

Hope it help u in someway 'n i had created a demo, u can download from here

Have a nice day... 'N happy Coding :)