phpseclib\Crypt\Rijndael::_subWord PHP Method

    function _subWord($word)
    {
        static $sbox;
        if (empty($sbox)) {
            list(, , , , $sbox) = $this->_getTables();
        }
        return $sbox[$word & 0xff] | $sbox[$word >> 8 & 0xff] << 8 | $sbox[$word >> 16 & 0xff] << 16 | $sbox[$word >> 24 & 0xff] << 24;
    }