I've seen papers saying toy ciphers can be improved with powerful key scheduling, but was wondering if there is evidence they are needed in reasonable ciphers? for instance AES. Is there any cryptanalysis which shows a strong cipher becomes dramatically weaker with simpler or no key scheduling?

  • $\begingroup$ also : crypto.stackexchange.com/questions/33975/… $\endgroup$
    – Biv
    May 28, 2017 at 9:41
  • $\begingroup$ It all depends on the specific cipher you're talking about. Some ciphers have a trivial key-schedule, (e.g. Threefish) for others a strong key-schedule is a critical part. $\endgroup$ May 28, 2017 at 9:42