I'd like to see a mod that would allow me to lock doors and chests... I've thought of a way this could work though I may explain it weird and/or make it to complicated but I'd like to be able to craft keys then a menu pops up much like on a sign. It will let you assign the key a number/password. When you craft doors/chests you will have the same menu pop up but if you don't input anything it will not need a key.
Second I would find it useful if you could make a key ring so that you can have multiple keys... simply put this would run on variables. If you have a key with the number/password on the ring then it will read as 1/true and the door/chest will open. If not then the door will simply not open.
it could also be a different recipe for locked doors/chests
Finally I've got a basic Idea for the recipes:
  
Let me know what you guys think. Also if someone likes the idea but doesn't want to take it up but knows how...
if you can let me know how to access the Java code I'm sure I could figure it out with time.