Encrytion and decryption a string [modified]

[C# Programming]

Hello anyone..,
How we can differentiate between an encrypted and none encrypted txt???

i need a method for that, to using in my project...,
Please help me.........,,,

An encryption methode is below:

using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using System.Configuration;

namespace SharpPcap.EnCryptDecrypt
{
public class CryptorEngine
{
public static string Encrypt(string toEncrypt, bool useHashing)
{
byte[] keyArray;
byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(toEncrypt);

System.Configuration.AppSettingsReader settingsReader = new AppSettingsReader();
// Get the key from config file
string key = (string)settingsReader.GetValue("SecurityKey", typeof(String));
//System.Windows.Forms.MessageBox.Show(key);
if (useHashing)
{
MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
hashmd5.Clear();
}
else
keyArray = UTF8Encoding.UTF8.GetBytes(key);

TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
tdes.Key = keyArray;
tdes.Mode = CipherMode.ECB;
tdes.Padding = PaddingMode.PKCS7;

ICryptoTransform cTransform = tdes.CreateEncryptor();
byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
tdes.Clear();
return Convert.ToBase64String(resultArray, 0, resultArray.Length);
}
}
}

Regards...

modified on Wednesday, January 27, 2010 6:56 AM