Just moved into my new flat.

It has DPS "High Security" locks which are (presumably) un-pickable.

However, I have one key which own both the communal front door and my own
flat's door.

I guessing that means that I can't change the cylinder and get a batch of
new keys as they then wont be able to open the front door (unless that is,
there's only one common door keying).

So I'm stuck with having to hope that previous tenants haven't kept a key
(Or worse, given one to their friends).

How is this good security?

tim