I have written a fairly long article, entitled “Can a Tabula Recta provide security in the XXI Century?” combining several posts from this website. The overarching assumption is that, in a world where connected computers are everywhere, we may get to a point where no electronic means within a given person’s reach can be trusted. What then? Use low-tech means that have been tweaked and optimized using computers, to stand against computer-aided attack if if comes to that. You can find the article here.