So I'm not sure what the current status of chest locks is right now, since I haven't been on Kiwike for a while... but I threw together this checkered fortress the other day.
View 1:
View 2:
View 3:
What this is, in the event that every one of these chests is equipped with a lock, is a very expensive yet 100% secure room.
None of these chests can be broken since they're locked, but I strategically placed them in a manner which makes it impossible to enter (or exit) unless you own the house.
Some more details:
The sides of the structure are composed of double and single chests in a diagonal pattern ensuring that there's no 2x1 hole for enemies to enter through.
The top and bottom of the structure are made in a double checkered pattern, on on top of the other, in a fashion which makes it impossible to tower up into or drop down into.
The map can be downloaded
here
Test this out. Download the .7z file, place it in your .minecraft/saves folder, and try to enter my fortress without breaking any chest blocks. Tower, place blocks, do anything you could do in Kiwike. Just don't break any chests.