[ahje]

> Wouldn't the guards simply torture you until you opened all of the locks?

Yes. Or just shoot you in the back when the door's open. Or something else.

Long-time survival in the event of society breakdown lies primarily in one's ability of re-building it, at least on a small, local scale. After all, sitting in a log cabin in the middle of nowhere might keep you alive for a while, but only until your food runs out, or your tools break and you lose your ability to sustain yourself.