encryption & decryption

[3bood ghzawi]

hi all, i use the following algorithms to encrypt then to decrypt a sequence of bytes, but the decryption algorithm always return an exception <Length of the data to decrypt is invalid< i don't know why that, both algorithms are below..,

public class CryptorEngine
{
static public byte[] keyArray;
static public byte[] resultArray;

    public static void Encrypt(byte\[\] toEncryptArray, bool useHashing)
    {
        System.Configuration.AppSettingsReader settingsReader = new AppSettingsReader();
        // Get the key from config file
        string key = (string)settingsReader.GetValue("SecurityKey", typeof(String));
        if (useHashing)
        {
            MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
            CryptorEngine.keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
            hashmd5.Clear();
        }
        else
            CryptorEngine.keyArray = UTF8Encoding.UTF8.GetBytes(key);

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

        ICryptoTransform cTransform = tdes.CreateEncryptor();
        CryptorEngine.resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
        tdes.Clear();
    }
}

////////////////////////////////////////////////////////////////////////////

public class DecryptorEngine
{
    static public byte\[\] keyArray;
    static public byte\[\] resultArray;
    
    public static void Decrypt(byte\[\] toEncryptArray, bool useHashing)
    {
       System.Configuration.AppSettingsReader settingsReader = new AppSettingsReader();
        //Get your key from config file to open the lock!
        string key = (string)settingsReader.GetValue("SecurityKey", typeof(String));

        if (useHashing)
        {
            MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
            DecryptorEngine.keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
            hashmd5.Clear();
        }
        else
            DecryptorEngine.keyArray = UTF8Encoding.UTF8.GetBytes(key);

        TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
        tdes.Key = keyArray;
        tdes