A processing system includes a processing core and a hardware accelerator communicatively coupled to the processing core. The hardware accelerator includes a random number generator to generate a byte order indicator. The hardware accelerator also includes a first switching module communicatively coupled to the random value indicator generator. The switching module receives an byte sequence in an encryption round of the cryptographic operation and feeds a portion of the input byte sequence to one of a first substitute box (S-box) module or a second S-box module in view of a byte order indicator value generated by the random number generator.