Apparently Travel Sentry locks can only be opened:
How do they work technically?
Is there some electronics embedded with authentication capabilities?
Do the security agencies have a kind of master code/key?
Do they have a big database giving the code for each individual lock? In that case I guess the lock has to emit some kind of identifier?
Apparently some have just a code, some other have just a key hole:
And some have both, see the pictures on Wikimedia Commons.