Hey, author here. I tried to write this article to be accessible to people with little background in security and cryptography (hence its publication on FreeCodeCamp), and to be friendly to non-developers. I took a few liberties with the crypto explanations (like calling a private key to a "secret password") in the hopes of making things more understandable for a general audience. Definitely didn't use rigorous language in just about anything here. :)
