Query String Encryption

protected string Encrypt(string text){
    try
    {
        byte[] keyData = 
            Encoding.UTF8.GetBytes(_keyString.Substring(0, 8));
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        byte[] textData = Encoding.UTF8.GetBytes(text);
        MemoryStream ms = new MemoryStream();
        CryptoStream cs = new CryptoStream(ms,
        des.CreateEncryptor(keyData, _keyBytes), CryptoStreamMode.Write);
        cs.Write(textData, 0, textData.Length);
        cs.FlushFinalBlock();
        return GetString(ms.ToArray());
    }
    catch (Exception)
    {
        return String.Empty;
    }

}