code/game/objects/structures/safe.dm

/obj/structure/safe	A locked container that can only be opened by entering a combination through a dial.
/obj/structure/safe/floor	Like a safe, but without density. Can be hidden with flooring.
/obj/item/safe_internals	Can be used to replace a safe's broken mechanism.
/obj/item/paper/safe_code	Contains the (generated on map load) codes for all publicly known safes.