phpseclib\Crypt\RC4::_setupKey PHP Метод

    function _setupKey()
    {
        $key = $this->key;
        $keyLength = strlen($key);
        $keyStream = range(0, 255);
        $j = 0;
        for ($i = 0; $i < 256; $i++) {
            $j = $j + $keyStream[$i] + ord($key[$i % $keyLength]) & 255;
            $temp = $keyStream[$i];
            $keyStream[$i] = $keyStream[$j];
            $keyStream[$j] = $temp;
        }
        $this->stream = array();
        $this->stream[self::DECRYPT] = $this->stream[self::ENCRYPT] = array(0, 0, $keyStream);
    }