The Lock is an item which can be crafted out of 2 obsidian, 2 iron, and 4 dyes of any kind (the dyes can be mixed, their order does not matter). The lock can be placed on any door, chest, trapped chest, fence gate, trapdoor, or chest minecart  and will prevent the object from being opened both by players and by redstone.

The unique combination of dyes used in craftin can also be used to make a key which will unlock the lock, which will then stay unlocked until the device it protects is opened and closed again. The lock can only be broken by a level 3+ pickaxe due to it's obsidian crafting, but it will not make the door any more difficult to break.
