Check this out. Haven’t tried it to see how advanced it is, but it’s free so worth a look
Discussion
Not trying to specifically recommend bitcoin but the road will lead there. Thnx.
There is a cryptography unit in that link I gave you
I understand. Just trying to avoid bitcoin labeled things right now to avoid parental scrutiny. They already know I’m a bitcoiner but I’m just recommending cryptography in general right now. If the HSer likes it, bitcoin will become a topic to pursue.