These codes are really just little puzzles, modern cryptography has no weaknesses of the kind these codes have.

There are even sites that teach you about bad modern cryptography, like cryptohack [0] but in general the kind of skills you learn there won't be useful either unless you happen to find a piece of software that rolled their own crypto and did something really dumb (which does happen, occasionally, see the Sony PS3 hack where they used a not-so-random value for crypto, which made it broken)

[0]: https://cryptohack.org/

No doubt it's an excellent strategy to identity where any future/potential opposition may come from.

As Sun Tzu says in The Art of War:

"If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.

What if you know the enemy, but not yourself?

You will spend $750B per year on a military that hasn't won a war in generations.

Or just never won a high intensity war alone.

I'll answer that with an examiner's question:

Please provide a T-F truth table to show that the proposition is false.

Clue: you already have the answer and Sun Tzu has provided three-quarters of it

:-)