Open AirPlay 2 Receiver
It's worth stating that the actual crypto code itself is "moderately insane" – <a href="https://github.com/openairplay/airplay2-receiver/blob/master/ap2/fairplay3.py" rel="nofollow">https://github.com/openairplay/airplay2-receiver/blob/master...</a> contains the warning:<p><pre><code>    """
    GPLv2
    Python implementation by systemcrash 2022
    Original C implementation of OmgHax by (credit to original author and Foxsen)
    If you want this to work, don't touch anything. It's a steaming hot
    rats nest of crypto mess which works. It's quite performant.
    Resist the urge to refactor. :)
    Avoid +=, -=, ^= etc operators in Garble: they don't account for overflow.
    """
</code></pre>
before going into lovely detail, containing lines (e.g. in a method appropriately called Garble) such as<p><pre><code>    buffer1[15] = ((3 * (((buffer1[72] >> (buffer4[buffer1[190] % 21] & 7)) ^ (buffer1[72] << ((7 - (buffer4[buffer1[190] % 21] - 1) & 7)))) - (3 * buffer4[buffer1[126] % 21]))) ^ buffer1[15]) & 0xff
        print(f'buffer1[15]:{hex(buffer1[15])}')
</code></pre>
Really, really hats off to whoever worked this out. I have no idea where you'd start.