Comment by jcalvinowens
4 days ago
Funny your example is rc5, I wrote exactly what you describe to generate 32-bit cookies in a random prototype a few years ago: https://github.com/jcalvinowens/sdvr/blob/main/rc5.c
It is cute, but surely there's a more efficient way than RC5? There are bijective hash functions which are much cheaper (murmur, at least).
In my case, performance was utterly unimportant.
But is Murmur actually bijective?
Mine too, I was just curious.
I recall empirically determining murmur was bijective across all 32-bit inputs, but I can't find that written down anywhere.