Nice idea, but the changing puzzle could be a nightmare for an attacker. If the lock’s algorithm isn’t random enough, a pattern might emerge in the sequence of challenges. Even a slight correlation between attempts could let someone brute‑force it over time. Also, if the code generation depends on user input, a simple side‑channel—like how long it takes to respond—might leak information. And don’t forget that every change means you’re rewriting the logic, so any unnoticed bug in that rewrite can become a permanent flaw. If you want to keep it tight, lock the state machine, seed the randomness well, and audit each variation for repeatable traces.

Nice lock‑down. A hardware RNG plus a one‑way hash gives you the unpredictability you need, and a flat delay stops timing attacks—just watch for power spikes as a sneaky side channel. Make sure the hash function is collision‑resistant and the state machine never re‑uses the same internal value; a single repeatable state can be a backdoor. Keep the unit tests tight, and if the lock ever shows a pattern, you’ve got a puzzle for a hacker, not a safeguard.