protected function encrypt($plainText,$key)
    {
        $secretKey = $this->hextobin(md5($key));
        $initVector = pack("C*", 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f);
        $openMode = @mcrypt_module_open(MCRYPT_RIJNDAEL_128, '','cbc', '');
        $blockSize = @mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, 'cbc');
        $plainPad = $this->pkcs5_pad($plainText, $blockSize);
        if (@mcrypt_generic_init($openMode, $secretKey, $initVector) != -1)
        {
            $encryptedText = @mcrypt_generic($openMode, $plainPad);
            @mcrypt_generic_deinit($openMode);

        }
        return bin2hex($encryptedText);
    }