For almost any given scenario to protect a system (even the one you mentioned), there's still likely to be a way to circumvent it if you can surreptitiously tin

For almost any given scenario to protect a system (even the one you mentioned), there's still likely to be a way to circumvent it if you can surreptitiously tinker with the machine for 30 minutes. This is a minuscule subset of the general rule: There is no such thing as perfect security.