Lemma rt3_equiv : forall n : nat, (n < 256)%nat -> let b := nth n inv_sbox Int.zero in (* (0x09, 0x0d, 0x0b, 0x0e) *) nth n RT3 Int.zero = word_to_int (ff_mult b (Int.repr 9), ff_mult b (Int.repr 13), ff_mult b (Int.repr 11), ff_mult b (Int.repr 14)).