Comment by mike_hearn
2 years ago
What I mean is that (assuming the sbox values are actually random) you couldn't memorize it short of intensive study and practice of memory techniques. If the "sbox" is in reality some easily memorizable function then maybe, but even then, how many people can remember long hex values from their old jobs?
Two points:
a) If a person is using those values daily for years (or even a couple of months), then it's very likely they'd have memorized them
b) Sometimes just knowing the concept exists for sure is good enough, as you can then go and brute force things until you've worked out the values
But having predictably generated sequence of numbers is what cryptographers prefer
https://en.wikipedia.org/wiki/Nothing-up-my-sleeve_number