phpseclib\Crypt\RC2::_setupKey PHP Method

    function _setupKey()
    {
        if (!isset($this->key)) {
            $this->setKey('');
        }
        // Key has already been expanded in \phpseclib\Crypt\RC2::setKey():
        // Only the first value must be altered.
        $l = unpack('Ca/Cb/v*', $this->key);
        array_unshift($l, $this->pitable[$l['a']] | $l['b'] << 8);
        unset($l['a']);
        unset($l['b']);
        $this->keys = $l;
    }