You should be doing both really. This, however, is not a good solution. A starter relay kill switch, hidden somewhere non-obvious, is far better. Not a suitabl

You should be doing both really. This, however, is not a good solution. A starter relay kill switch, hidden somewhere non-obvious, is far better. Not a suitable solution for mass-market of course, but, for a hacky intermediate solution, it'll work just fine, which is all the power sensing keypad is good for but with way more steps. The actual solution is to have real cryptographic security that isn't subject to replay attacks. Not difficult to do, or expensive, and already exists.