A lot more goes into off-the-record messaging than I thought. Suddenly I can appreciate all those end-to-end encrypted messaging services a lot more.
Robert Heaton posted a great overview of how off-the-record messaging works, as well as some of the pitfalls of PGP encryption that it avoids. It's a great read if you're interested in cryptography at all.
Heaton's a terrific writer in general. His style is easygoing, levelheaded but not bland, authoritative. He's written a few guides on writing and an ongoing series about being a new father that's compelling even to folks who never plan to have children. Being a security guy at Stripe, though, his bread & butter is encryption & tracking; he is very good at writing about it.