将C＃转换为php？

Question

I'm trying to convert this function from C# to php, but how do I deal with needing to type cast to a byte data type (up to 0xFF) when php only deals with integers?

public static byte[] CreateKeyBlock()
{
    byte[] ac = new byte[6];
    for (int j = 0; j < 6; j++)
    {
        ac[j] = (byte)Rand.Next(0, 255);
        int i;
        byte d;

        ac[3] = (byte)(ac[1] ^ ac[2] ^ ac[4]);
        ac[0] = (byte)((ac[4] ^ ac[1]) + ac[2]);
        ac[5] = 0;
        d = (byte)0xd5;

        for (i = 0; i < 102; i++)
        {
            if (i % 5 != 0)
            {
                ac[(i % 6)] = (byte)(ac[(i % 6)] + d);
                d = ac[(i % 6)];
            }
            else
            {
                ac[(i % 6)] = (byte)(ac[(i % 6)] ^ d);
                d = ac[(i % 6)];
            }
        }
    }

    return ac;
}

Answer 1

function CreateKeyBlock()
{
    $ac = '';

    for ($j = 0; $j < 6; $j++)
    {
        $ac{$j} = rand(0, 255);

        $ac{3} = ($ac{1} ^ $ac{2} ^ $ac{4}) & 0xff;
        $ac{0} = (($ac{4} ^ $ac{1}) + $ac{2}) & 0xff;
        $ac{5} = 0;

        $d = 0xd5;

        for ($i = 0; $i < 102; $i++)
        {
            if ($i % 5 != 0)
            {
                $ac{($i % 6)} = ($ac{($i % 6)} + $d) & 0xff;
                $d = $ac{($i % 6)};
            }
            else
            {
                $ac{($i % 6)} = ($ac{($i % 6)} ^ $d) & 0xff;
                $d = $ac{($i % 6)};
            }
        }
    }
    return $ac;
}