Simple Solutions: Electronics

There is a tendency in electronics today towards complete technological overkill. It doesn't always work. There is an example in the news today: Millions of Car Remotes Susceptible to Hacking. In this case, computer security experts worked out how to hack the keyless entry systems of millions of cars / automobiles, presumably all at once. But often it is the simple designs which are virtually 100% secure. Supposing, for instance, that one would need to unlock a car door by clapping twice 1.5 seconds apart, or blowing a dog whistle tuned to 21kHz, or touching a car aerial. That's what extremely simple (and cheap) solutions look like. However, mass production may then be a problem.