ROM Hack 3DS AES Keyscrambler function

[neotil1]

I don't know if this is the right category, if not please move this thread.

I'm trying to understand the way the keyscrambler function for the 3DS was found. I've read the post by Myria in the thread "AES key scrambler" on page 8 (sorry, I can't post links), but I don't understand what they mean by this:

If you guess that the new G function on X and Y is still an XOR on 3DS keyslots, you can just try a few things and derive that G(X, Y) = (X ROL 2) XOR Y. It's easy to test it without knowing C or S.

What does "try a few things" mean? I am relatively new to cryptography so I apologise if this is obvious, but I have spent a lot of time trying to figure this out and still don't understand. I do understand bitwise operations and most of the other post, though.

Any help would be greatly appreciated!

 

[zoogie]

Watch this video at the timestamp. Plutoo explains it in detail.

1:14:18 timestamp.