Have you ever built a NN model? Have you ever broken a crypto system, even a small one?

yes and yes.

You can build and train a model in about 15 lines of pytorch. And you can build and break your own 8 bit xor cipher in about 10 lines of python.

Hacker news is full of software engineers. You are unlikely to find one that hasn't built a model using pytorch these days, and an xor cipher is a common university lab exercise.