Cryptography as a concept is one thing. Understanding why it matters, how the mathematics work, what makes a key a key, that’s the foundation, and I covered it in Cryptography: The Weapon They Couldn’t Ban. But theory only gets you to the door. What’s on the other side is a terminal, a handful of CLI commands, and the particular satisfaction of holding something the system cannot touch. This guide is how I actually use GPG. My setup, my choices, my keys.