encryption & decryption

Class for encryption and decryption

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

// Encryption & Decryption using DES algorithm

public class clsDecrypt
{
//Encrypt function
public static string strEncrypt(string strData, string strKey1, string strKey2)
{
MemoryStream ms = new MemoryStream();

DESCryptoServiceProvider objKey = new DESCryptoServiceProvider();
objKey.Key = objLockKey(strKey1);
objKey.IV = objLockKey(strKey2);

CryptoStream encStream = new CryptoStream(ms,
objKey.CreateEncryptor(), CryptoStreamMode.Write);
StreamWriter sw = new StreamWriter(encStream);
sw.WriteLine(strData);
sw.Close();
encStream.Close();

byte[] bytData = ms.ToArray();
string strReturnData = "";

foreach (byte bytChar in bytData)
{
strReturnData += bytChar.ToString().PadLeft(3, Convert.ToChar("0"));
}
ms.Close();

return strReturnData;
}
//Decrypt function
public static string strDecrypt(string strData, string strKey1, string strKey2)
{

DESCryptoServiceProvider objKey = new DESCryptoServiceProvider();
objKey.Key = objLockKey(strKey1);
objKey.IV = objLockKey(strKey2);

Int16 intLength = Convert.ToInt16((strData.Length / 3));
byte[] bytData = new byte[intLength];

for (Int16 intCount = 0; intCount < intLength; intCount++)
{
string strChar = strData.Substring((intCount * 3), 3);
bytData[intCount] = Convert.ToByte(strChar);
}
MemoryStream ms = new MemoryStream(bytData);

CryptoStream encStream = new CryptoStream(ms,
objKey.CreateDecryptor(), CryptoStreamMode.Read);
StreamReader sr = new StreamReader(encStream);
string strReturnVal = sr.ReadLine();
sr.Close();
encStream.Close();
ms.Close();

return strReturnVal;
}
private static byte[] objLockKey(string strPassword)
{
const int intKeyLength = 8;
strPassword = strPassword.PadRight(intKeyLength,
Convert.ToChar(".")).Substring(0, intKeyLength);
byte[] objKey = new byte[strPassword.Length];
for (int intCount = 0; intCount < strPassword.Length; intCount++)
{
objKey[intCount] = Convert.ToByte(Convert.ToChar(strPassword.Substring(intCount, 1)));
}
return objKey;
}
}

Call the above function from any page as below
//encryption
string encpassword=clsDecrypt.strEncrypt(password,"choice1" ,"choice2");
//decryption
string password=clsDecrypt.string strDecrypt(encpassword,"choice1","choice2");

hopes this will help you...
Regards
maddy.....