Wooden locks and keys were in use as early as 4,000 years ago in Egypt [3]. It is also said that key was invented by Theodore of Samos in the 6^th century BC.

Early history of locks

Securing one's possessions has long been a concern of people throughout the world. Beyond hiding the objects or constantly guarding them the most frequently used option is to secure them with a device. Early solutions included knots to either detect, like the Thief knot, or hamper, like the Gordian knot.

Wooden locks and keys were in use as early as 4,000 years ago in Egypt [1]. The first known lock with a key is a pin lock. The lock is strung on a rope hanging out of a hole in a door. A cylinder of wood with a hole drilled through its axis is the key, the length of the cylinder being the critical factor. Then the key is inserted into the hole and the rope pulled to push the cylinder to push the bolt the correct distance. To lock the door, just pull on the rope to extract the key cylinder and simultaneously pulling the bolt closed. This type of lock is still in use in certain parts of the world. A danger of this lock is a vandal can push the rope into the hole — an ancient equivalent of putting glue into a lock.

Early improvements in pin locks included increasing the number of pins to increase security, and changing the orientation of the pins to allow the key to provide the unlocking force instead of a rope. Thus establishing the principles of the modern Pin tumbler lock.

Next was developed a warded lock that is still used in modern times when the security required is not high and cost is a significant factor. It is the first lock design to have a key recognizable to a modern western person. Lock puzzles were used to obscure the locking mechanism or even provide a nonfunctioning lock for the thief to waste time on.

SOURCE : wikipedia.org