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A lock is a
mechanical Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations ...
or electronic fastening device that is released by a physical object (such as a key, keycard,
fingerprint A fingerprint is an impression left by the friction ridges of a human finger. The recovery of partial fingerprints from a crime scene is an important method of forensic science. Moisture and grease on a finger result in fingerprints on surfac ...
,
RFID Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. An RFID system consists of a tiny radio transponder, a radio receiver and transmitter. When triggered by an electromag ...
card, security token or coin), by supplying secret information (such as a number or letter permutation or
password A password, sometimes called a passcode (for example in Apple devices), is secret data, typically a string of characters, usually used to confirm a user's identity. Traditionally, passwords were expected to be memorized, but the large number of ...
), by a combination thereof, or it may only be able to be opened from one side, such as a door chain. A key is a device that is used to operate a lock (to lock or unlock it). A typical key is a small piece of metal consisting of two parts: the '' bit'' or ''blade'', which slides into the
keyway Keyway may refer to: *A part of a keyed joint used to connect a rotating machine element to a shaft; see key (engineering) *A keyhole, a hole or aperture (as in a door or lock) for receiving a key; see lock and key A lock is a mechanical or elec ...
of the lock and distinguishes between different keys, and the ''bow'', which is left protruding so that torque can be applied by the user. In its simplest implementation, a key operates one lock or set of locks that are keyed alike, a lock/key system where each similarly keyed lock requires the same, unique key. The key serves as a security token for access to the locked area; locks are meant to only allow persons having the correct key to open it and gain access. In more complex mechanical lock/key systems, two different keys, one of which is known as the master key, serve to open the lock. Common metals include
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...
, plated brass, nickel silver, and
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...
.


History


Premodern history

Locks have been in use for over 6000 years, with one early example discovered in the ruins of
Nineveh Nineveh (; akk, ; Biblical Hebrew: '; ar, نَيْنَوَىٰ '; syr, ܢܝܼܢܘܹܐ, Nīnwē) was an ancient Assyrian city of Upper Mesopotamia, located in the modern-day city of Mosul in northern Iraq. It is located on the eastern ba ...
, the capital of ancient
Assyria Assyria ( Neo-Assyrian cuneiform: , romanized: ''māt Aššur''; syc, ܐܬܘܪ, ʾāthor) was a major ancient Mesopotamian civilization which existed as a city-state at times controlling regional territories in the indigenous lands of the A ...
. Locks such as this were developed into the
Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a List of transcontinental countries, transcontinental country spanning the North Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via a land bridg ...
ian wooden pin lock, which consisted of a bolt, door fixture or attachment, 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. The warded lock was also present from antiquity and remains the most recognizable lock and key design in the Western world. The first all-metal locks appeared between the years 870 and 900, and are attributed to the English craftsmen. It is also said that the key was invented by Theodorus of Samos in the 6th century BC. 'The Romans invented metal locks and keys and the system of security provided by wards.' Affluent Romans often kept their valuables in secure locked boxes within their households, and wore the keys as rings on their fingers. The practice had two benefits: It kept the key handy at all times, while signaling that the wearer was wealthy and important enough to have money and jewellery worth securing. A special type of lock, dating back to the 17th-18th century, although potentially older as similar locks date back to the 14th century, can be found in the
Beguinage A beguinage, from the French term ''béguinage'', is an architectural complex which was created to house beguines: lay religious women who lived in community without taking vows or retiring from the world. Originally the beguine institution was ...
of the Belgian city Lier.R. De Bruyn, ‘Oude sloten op deurtjes in het Liers begijnhof’, in: 't land van Ryen jaargang 17, aflevering 3–4, 1967, p. 158, article in DutchEchtpaar schrijft eerste boek sinds twintig jaar over Liers begijnhof
nieuwsblad.be, Chris van Rompaey, 17 april 2018, article in Dutch
These locks are most likely Gothic locks, that were decorated with foliage, often in a V-shape surrounding the keyhole. They are often called ''drunk man's lock'', however the reference to being drunk may be erroneous as these locks were, according to certain sources, designed in such a way a person can still find the keyhole in the dark, although this might not be the case as the ornaments might have been purely aesthetic. In more recent times similar locks have been designed.


Modern locks

With the onset of the
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
in the late 18th century and the concomitant development of precision engineering and component standardization, locks and keys were manufactured with increasing complexity and sophistication. The lever tumbler lock, which uses a set of levers to prevent the bolt from moving in the lock, was invented by Robert Barron in 1778. His double acting lever lock required the lever to be lifted to a certain height by having a slot cut in the lever, so lifting the lever too far was as bad as not lifting the lever far enough. This type of lock is still used today. The lever tumbler lock was greatly improved by Jeremiah Chubb in 1818. A burglary in
Portsmouth Dockyard His Majesty's Naval Base, Portsmouth (HMNB Portsmouth) is one of three operating bases in the United Kingdom for the Royal Navy (the others being HMNB Clyde and HMNB Devonport). Portsmouth Naval Base is part of the city of Portsmouth; it is ...
prompted the
British Government ga, Rialtas a Shoilse gd, Riaghaltas a Mhòrachd , image = HM Government logo.svg , image_size = 220px , image2 = Royal Coat of Arms of the United Kingdom (HM Government).svg , image_size2 = 180px , caption = Royal Arms , date_est ...
to announce a competition to produce a lock that could be opened only with its own key. Chubb developed the Chubb detector lock, which incorporated an integral security feature that could frustrate unauthorized access attempts and would indicate to the lock's owner if it had been interfered with. Chubb was awarded £100 after a trained lock-picker failed to break the lock after 3 months. In 1820, Jeremiah joined his brother
Charles Charles is a masculine given name predominantly found in English and French speaking countries. It is from the French form ''Charles'' of the Proto-Germanic name (in runic alphabet) or ''*karilaz'' (in Latin alphabet), whose meaning was " ...
in starting their own lock company, Chubb. Chubb made various improvements to his lock: his 1824 improved design didn't require a special regulator key to reset the lock; by 1847 his keys used six levers rather than four; and he later introduced a disc that allowed the key to pass but narrowed the field of view, hiding the levers from anybody attempting to pick the lock. The Chubb brothers also received a patent for the first burglar-resisting
safe A safe (also called a strongbox or coffer) is a secure lockable box used for securing valuable objects against theft or fire. A safe is usually a hollow cuboid or cylinder, with one face being removable or hinged to form a door. The body and ...
and began production in 1835. The designs of Barron and Chubb were based on the use of movable levers, but
Joseph Bramah Joseph Bramah (13 April 1748 – 9 December 1814), born Stainborough Lane Farm, Stainborough, in Barnsley, Yorkshire, was an English inventor and locksmith. He is best known for having improved the flush toilet and inventing the hydraulic p ...
, a prolific inventor, developed an alternative method in 1784. His lock used a cylindrical key with precise notches along the surface; these moved the metal slides that impeded the turning of the bolt into an exact alignment, allowing the lock to open. The lock was at the limits of the precision manufacturing capabilities of the time and was said by its inventor to be unpickable. In the same year Bramah started the Bramah Locks company at 124 Piccadilly, and displayed the "Challenge Lock" in the window of his shop from 1790, challenging "...the artist who can make an instrument that will pick or open this lock" for the reward of £200. The challenge stood for over 67 years until, at the
Great Exhibition The Great Exhibition of the Works of Industry of All Nations, also known as the Great Exhibition or the Crystal Palace Exhibition (in reference to the temporary structure in which it was held), was an international exhibition which took pl ...
of 1851, the American locksmith
Alfred Charles Hobbs Alfred Charles Hobbs (October 7, 1812 – November 6, 1891) was an American locksmith and inventor. He was born in Boston, Massachusetts, in 1812; his father was a carpenter. He married Charlotte F. Nye (1815-?) of Sandwich, Massachusetts, ...
was able to open the lock and, following some argument about the circumstances under which he had opened it, was awarded the prize. Hobbs' attempt required some 51 hours, spread over 16 days. The earliest patent for a double-acting pin tumbler lock was granted to American physician Abraham O. Stansbury in England in 1805, but the modern version, still in use today, was invented by American Linus Yale Sr. in 1848. This lock design used pins of varying lengths to prevent the lock from opening without the correct key. In 1861,
Linus Yale Jr. Linus Yale Jr. (April 4, 1821 – December 25, 1868) was an American mechanical engineer, manufacturer, and co-founder with Henry R. Towne of the Yale Lock Manufacturing Company, which became the premier manufacturer of locks in the Unit ...
was inspired by the original 1840s pin-tumbler lock designed by his father, thus inventing and patenting a smaller flat key with serrated edges as well as pins of varying lengths within the lock itself, the same design of the pin-tumbler lock which still remains in use today. The modern Yale lock is essentially a more developed version of the Egyptian lock. Despite some improvement in key design since, the majority of locks today are still variants of the designs invented by Bramah, Chubb and Yale.


Types of lock

* Bicycle lock * Cam lock * Chamber lock *
Child safety lock A child safety lock is a special-purpose lock for cabinets, drawers, bottles, etc. that is designed to help prevent children from getting at any dangerous things or contents. Young children are naturally curious about their surroundings and will al ...
* Chubb detector lock *
Combination lock A combination lock is a type of locking device in which a sequence of symbols, usually numbers, is used to open the lock. The sequence may be entered using a single rotating dial which interacts with several discs or ''cams'', by using a set o ...
* Cylinder lock * Dead bolt * Disc tumbler lock * Electric strike *
Electromagnetic lock An electromagnetic lock, magnetic lock, or maglock is a locking device that consists of an electromagnet and an armature plate. There are two main types of electric locking devices. Locking devices can be either "fail safe" or "fail secure". A fai ...
* Electronic lock * Lever tumbler lock * Lock screen *
Luggage lock A luggage lock is a lock used to prevent luggage from opening by accident, usually with little or no security in mind, although the lock may serve as a deterrent to potential thieves. Luggage locks may be built into luggage or may be external l ...
* Magnetic keyed lock * Mortise lock * Padlock * Pin tumbler lock * Police lock * Protector lock * Rim lock * Time lock


With physical keys

Pin tumbler no key.svg, Pin tumbler lock: without a key in the lock, the driver pins (blue) are pushed downwards, preventing the plug (yellow) from rotating. Disc tumbler locked.png, Wafer tumbler lock: without a key in the lock, the wafers (red) are pushed down by springs. The wafers nestle into a groove in the lower part of the outer cylinder (green) preventing the plug (yellow) from rotating. Tubular locked.png, Tubular lock: the key pins (red) and driver pins (blue) are pushed towards the front of the lock, preventing the plug (yellow) from rotating. The tubular key has several half-cylinder indentations which align with the pins. A warded lock uses a set of obstructions, or wards, to prevent the lock from opening unless the correct key is inserted. The key has notches or slots that correspond to the obstructions in the lock, allowing it to rotate freely inside the lock. Warded locks are typically reserved for low-security applications as a well-designed
skeleton key A skeleton key (also known as a passkey) is a type of master key in which the serrated edge has been removed in such a way that it can open numerous locks, most commonly the warded lock. The term derives from the fact that the key has been r ...
can successfully open a wide variety of warded locks. The pin tumbler lock uses a set of pins to prevent the lock from opening unless the correct key is inserted. The key has a series of grooves on either side of the key's blade that limit the type of lock the key can slide into. As the key slides into the lock, the horizontal grooves on the blade align with the wards in the
keyway Keyway may refer to: *A part of a keyed joint used to connect a rotating machine element to a shaft; see key (engineering) *A keyhole, a hole or aperture (as in a door or lock) for receiving a key; see lock and key A lock is a mechanical or elec ...
allowing or denying entry to the
cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an ...
. A series of pointed teeth and notches on the blade, called bittings, then allow
pins A pin is a device used for fastening objects or material together. Pin or PIN may also refer to: Computers and technology * Personal identification number (PIN), to access a secured system ** PIN pad, a PIN entry device * PIN, a former Dutch de ...
to move up and down until they are in line with the shear line of the inner and outer cylinder, allowing the cylinder or cam to rotate freely and the lock to open. An additional pin called the master pin is present between the key and driver pins in locks that accept master keys, to allow the plug to rotate at multiple pin elevations. A wafer tumbler lock is similar to the pin tumbler lock and works on a similar principle. However, unlike the pin lock (where each pin consists of two or more pieces) each wafer is a single piece. The wafer tumbler lock is often incorrectly referred to as a disc tumbler lock, which uses an entirely different mechanism. The wafer lock is relatively inexpensive to produce and is often used in automobiles and cabinetry. The disc tumbler lock or Abloy lock is composed of slotted rotating detainer discs. The lever tumbler lock uses a set of levers to prevent the bolt from moving in the lock. In its simplest form, lifting the tumbler above a certain height will allow the bolt to slide past. Lever locks are commonly recessed inside wooden doors or on some older forms of padlocks, including fire brigade padlocks. A magnetic keyed lock is a locking mechanism whereby the key utilizes magnets as part of the locking and unlocking mechanism. A magnetic key would use from one to many small magnets oriented so that the North and South poles would equate to a combination to push or pull the lock's internal tumblers thus releasing the lock.


With electronic keys

An electronic lock works by means of an electric current and is usually connected to an
access control In the fields of physical security and information security, access control (AC) is the selective restriction of access to a place or other resource, while access management describes the process. The act of ''accessing'' may mean consuming ...
system. In addition to the pin and tumbler used in standard locks, electronic locks connect the bolt or
cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an ...
to a motor within the door using a part called an actuator. Types of electronic locks include the following: A keycard lock operates with a flat card of similar dimensions as a
credit card A credit card is a payment card issued to users (cardholders) to enable the cardholder to pay a merchant for goods and services based on the cardholder's accrued debt (i.e., promise to the card issuer to pay them for the amounts plus the ...
. In order to open the door, one needs to successfully match the signature within the ''keycard''. The lock in a typical remote keyless system operates with a smart key radio transmitter. The lock typically accepts a particular valid code only once, and the smart key transmits a different rolling code every time the button is pressed. Generally the car door can be opened with either a valid code by radio transmission, or with a (non-electronic) pin tumbler key. The ignition switch may require a
transponder car key In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a flight tran ...
to both open a pin tumbler lock and also transmit a valid code by radio transmission. A smart lock is an electromechanics lock that gets instructions to lock and unlock the door from an authorized device using a cryptographic key and wireless protocol. Smart locks have begun to be used more commonly in residential areas, often controlled with
smartphones A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...
. Smart locks are used in
coworking Coworking is an arrangement in which workers for different companies share an office space. It allows cost savings and convenience through the use of common infrastructures, such as equipment, utilities and receptionist and custodial services, a ...
spaces and offices to enable keyless office entry. In addition, electronic locks cannot be picked with conventional tools.


Locksmithing

Locksmithing is a traditional trade, and in most countries requires completion of an
apprenticeship Apprenticeship is a system for training a new generation of practitioners of a trade or profession with on-the-job training and often some accompanying study (classroom work and reading). Apprenticeships can also enable practitioners to gain a ...
. The level of formal education required varies from country to country, from no qualifications required at all in the UK, to a simple training certificate awarded by an employer, to a full
diploma A diploma is a document awarded by an educational institution (such as a college or university) testifying the recipient has graduated by successfully completing their courses of studies. Historically, it has also referred to a charter or offici ...
from an
engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range of more speciali ...
college A college (Latin: ''collegium'') is an educational institution or a constituent part of one. A college may be a degree-awarding tertiary educational institution, a part of a collegiate or federal university, an institution offerin ...
. Locksmiths may be commercial (working out of a storefront), mobile (working out of a vehicle), institutional, or investigational (forensic locksmiths). They may specialize in one aspect of the skill, such as an automotive lock specialist, a master key system specialist or a safe technician. Many also act as security consultants, but not all security consultants have the skills and knowledge of a locksmith. Historically, locksmiths constructed or repaired an entire lock, including its constituent parts. The rise of cheap mass production has made this less common; the vast majority of locks are repaired through like-for-like replacements, high-security safes and strongboxes being the most common exception. Many locksmiths also work on any existing door hardware, including door closers, hinges, electric strikes, and frame repairs, or service electronic locks by making keys for transponder-equipped vehicles and implementing access control systems. Although the fitting and replacement of keys remains an important part of locksmithing, modern locksmiths are primarily involved in the installation of high quality lock-sets and the design, implementation, and management of keying and key control systems. Locksmiths are frequently required to determine the level of risk to an individual or institution and then recommend and implement appropriate combinations of equipment and policies to create a "security layer" that exceeds the reasonable gain of an intruder.


Key duplication

Traditional key cutting is the primary method of key duplication. It is a subtractive process named after the metalworking process of cutting, where a flat ''blank'' key is ground down to form the same shape as the ''template'' (original) key. The process roughly follows these stages: # The original key is fitted into a
vise A vise or vice (British English) is a mechanical apparatus used to secure an object to allow work to be performed on it. Vises have two parallel jaws, one fixed and the other movable, threaded in and out by a screw and lever. A vise grip is n ...
in a machine, with a blank attached to a parallel vise which is mechanically linked. # The original key is moved along a guide in a movement which follows the key's shape, while the blank is moved in the same pattern against a cutting wheel by the mechanical linkage between the vices. # After cutting, the new key is deburred by scrubbing it with a metal brush to remove particles of metal which could be dangerously sharp and foul locks. Modern key cutting replaces the mechanical key following aspect with a process in which the original key is scanned electronically, processed by software, stored, then used to guide a cutting wheel when a key is produced. The capability to store electronic copies of the key's shape allows for key shapes to be stored for key cutting by any party that has access to the key image. Different key cutting machines are more or less automated, using different milling or grinding equipment, and follow the design of early 20th century key duplicators. Key duplication is available in many retail hardware stores and as a service of the specialized locksmith, though the correct key blank may not be available. More recently, online services for duplicating keys have become available.


Keyhole

A keyhole (or keyway) is a hole or aperture (as in a door or lock) for receiving a key. Lock keyway shapes vary widely with lock manufacturer, and many manufacturers have a number of unique profiles requiring a specifically milled
key blank Key or The Key may refer to: Common meanings * Key (cryptography), a piece of information that controls the operation of a cryptography algorithm * Key (lock), device used to control access to places or facilities restricted by a lock * Key (ma ...
to engage the lock's tumblers.


Symbolism


Heraldry

Keys appear in various symbols and coats of arms, the best-known being that of the
Holy See The Holy See ( lat, Sancta Sedes, ; it, Santa Sede ), also called the See of Rome, Petrine See or Apostolic See, is the jurisdiction of the Pope in his role as the bishop of Rome. It includes the apostolic episcopal see of the Diocese of R ...
: derived from the phrase in which promises
Saint Peter ) (Simeon, Simon) , birth_date = , birth_place = Bethsaida, Gaulanitis, Syria, Roman Empire , death_date = Between AD 64–68 , death_place = probably Vatican Hill, Rome, Italia, Roman Empire , parents = John (or Jonah; Jona) , occupat ...
, in Roman Catholic tradition the first
pope The pope ( la, papa, from el, πάππας, translit=pappas, 'father'), also known as supreme pontiff ( or ), Roman pontiff () or sovereign pontiff, is the bishop of Rome (or historically the patriarch of Rome), head of the worldwide Cathol ...
, the
Keys of Heaven The Keys of Heaven, also called Saint Peter's keys, refers to the metaphorical keys of the office of Saint Peter, the keys of Heaven in Christianity, Heaven, or the keys of the kingdom of Heaven. It is explicitly referenced in the Bible in Matthew ...
. But this is by no means the only case. Many examples are given on Commons. File:Coat of arms Holy See.svg,
Coat of arms A coat of arms is a heraldic visual design on an escutcheon (i.e., shield), surcoat, or tabard (the latter two being outer garments). The coat of arms on an escutcheon forms the central element of the full heraldic achievement, which in its ...
of the
Holy See The Holy See ( lat, Sancta Sedes, ; it, Santa Sede ), also called the See of Rome, Petrine See or Apostolic See, is the jurisdiction of the Pope in his role as the bishop of Rome. It includes the apostolic episcopal see of the Diocese of R ...
File:Siuntio.vaakuna.svg, A key pictured in the coat of arms of Siuntio


Artwork

Some works of art associate keys with the Greek goddess of
witchcraft Witchcraft traditionally means the use of magic or supernatural powers to harm others. A practitioner is a witch. In medieval and early modern Europe, where the term originated, accused witches were usually women who were believed to have ...
known as
Hecate Hecate or Hekate, , ; grc-dor, Ἑκάτᾱ, Hekátā, ; la, Hecatē or . is a goddess in ancient Greek religion and mythology, most often shown holding a pair of torches, a key, snakes, or accompanied by dogs, and in later periods depict ...
.


See also

* Door security *
Exit control lock An exit control lock, also known as an exit control device, exit lock, or simply an exit control, prevents or deters unauthorized exit.Keyless Locks Have Versatile Features That Protect Lives and Contain Situations By Jack M Patterson Typical ...
* Key relevance *
Physical security Physical security describes security measures that are designed to deny unauthorized access to facilities, equipment and resources and to protect personnel and property from damage or harm (such as espionage, theft, or terrorist attacks). Phy ...


References


Further reading

* Phillips, Bill. (2005). ''The Complete Book of Locks and Locksmithing.'' McGraw-Hill. . * Alth, Max (1972). ''All About Locks and Locksmithing.'' Penguin. * Robinson, Robert L. (1973). ''Complete Course in Professional Locksmithing'' Nelson-Hall.


External links


Historical locks
by Raine Borg and ASSA ABLOY
Picking Locks
''Popular Mechanics'' {{Authority control Door furniture * Physical security id:Kunci