A key generated from a seed consisting only of the number four can be reverse engineered.

“Uh, you know, that's why Cloudflare has our lava lamps is so that, uh, uh, you can get good randomness. Uh, and when, uh, uh, a key out there is, uh, they use the seed, they use the initial, uh, uh, thing to, uh, uh, kind of create it, uh, with a single number four, uh, uh, it's, it's gonna be, uh, uh, reverse engineered.”