Have you been on the sever and someone walks in your house and stuffs it up or takes something? how about having a key for a door so it will only open to that key so only you or whoever else you gave that key to can open the door and get in.
There are already a mod for chest and door ( lockette ). place a sign near a chest / door type [private] on the first line and TADA ... u have a locked door and chest .... for your idea .. i don't like .. what if something killed u and u can't find the key back ? u dropped into lava ? people poke a hole in your wall to get in ? think about it ~