It would seem that would get to work on the large and important things if you pick up cryptography as a skill.
I think there should be a class on how to roll your own crypto, because someone's got to do it, and, as we saw with Heartblead, you don't want something like crypto to be something only a handful of people in the world to understand.
Never implemented any algorithms but every assignment involved breaking bad implementations of crypto or various applications which was extremely interesting.
Pretty much every lecture slide had a disclaimer "never implement * yourself, Use respected crypto libraries!!!".
My main hesitancy with the really domain specific courses offered in college is that the careers associated with them are all or nothing. Adding stuff like machine learning/AI, cryptography, etc. to your skill set as a standard software engineer is super hard to do in a practical manner.