It seems that the article is trying an artsy way to introduce cryptography and hashing: Communication is easy, but it’s hard to tell who knows what. Messages p

It seems that the article is trying an artsy way to introduce cryptography and hashing: Communication is easy, but it’s hard to tell who knows what. Messages pass one another in corridors; conversations fragment. When A replied to B, had she received your message yet, or was she reading C’s? Did she ignore what you said because she didn’t like it, or because it had yet to be delivered? When D proposes a simultaneous attack on the wardens as they deliver dinner, how many people received it? When A confirms to D that she’s in, will D see the message in time? Will D know that B saw it? Here’s one solution, if a strange one. Write a message with a very difficult mathematical problem on it—a problem so hard that it would take a month of concentration to solve. Now wait. And I don't get the point of this. Is cryptography bad because it needs to ensure things are not intercepted in between?