lock and key

Lock and key 18th c. Mexico

Lock – a mechanical or electronic fastening device that is released by a physical object (such as a key, keycard, fingerprint, RFID card, or security token), by supplying secret information (such as a keycode or password), or by a combination of these.

  • the key was invented by Theodore of Samos in the 6th century BC
  • Egyptian wooden pin lock, which consisted of a bolt, door fixture, and key. When the key was inserted, pins within the fixture were lifted out of drilled holes within the bolt, allowing it to move. When the key was removed, the pins fell part-way into the bolt, preventing movement
  • In Roman times, small keys made from metals (iron, bronze, silver, gold) were often viewed as one of the most effective ways of publicly showing your wealth (only very rich people could afford to have personal safes or doors with locking mechanisms)
  • Keys were used mainly for doors, chests, boxes, caskets, cupboards and padlocks. Less often they were used for ceremonial or decorative purposes, such as matron keys, jewelry items and votive offerings.
  • first all-metal lock (870 – 900), attributed to English craftsmen

What is it good for?

  • keeping something from moving – usually associated with a bolt that, when held in place, prevents opening a door or lid, preventing access or escape.
  • protection – Originally created using wood and other easily accessible natural materials, locks and keys offered small manner of protection against theft or intrusion, but they (as well as complicated rope knots) at least provided clear indicator if someone tampered with the lock.
parts of a lever-type lock key

Types of locks, locking mechanisms

  • rope knots
  • warded lock – from antiquity, recognizable lock and key design
  • falling pins – control the movement of the security bolt. The bolt could be freed from locked position by inserting large and cumbersome wooden key into the lock, and manually lifting it upwards, displacing the pins that were held down by gravity.
  • padlock – small, portable – numerous sizes (from protecting bicycles to large hangars), types (keys, combination locks), and security ratings (regulated by government sponsored organizations from all around the world).
  • tubular
  • time lock
  • “smart” devices lock and unlock home doors, garage doors or gates with any smartphones, cell phones and secure smart keys, built-in alarm notification when an intruder attempts to enter door.


  • wooden
  • metal
  • plastic keycard
  • combination


  • Charles Chubb (1772 – 1846) Founder of the Chubb firm
  • Joseph Bramah (1749 – 1814) Patentee of a locking principal that didn’t rely on fixed wards or complicated shapes.
  • George Price {1819 – 1887} Author of “The Locksmiths Bible”
  • Yale

Engineering ideas

  • key, keycard, fingerprint, RFID card, security token, keycode, password, tumbler

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