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A lock is 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 thereof.
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The earliest known lock and key device was discovered in the ruins of Nineveh, the capital of ancient Assyria. Locks such as this were later developed into the 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 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.
A number of modern locks, and improved ancient locks, have been developed since the eighteenth century. The level tumbler lock was invented in Europe in the 17th century and improved in 1778 by Robert Barron, who invented the 'double acting' lever tumbler lock. The first patent for the wafer tumbler lock was issued in the United States in 1868 to P. S. Felter. The disc tumbler lock or Abloy Disklock was invented by a Finnish mechanic Emil Henriksson in 1907.
Types of locks
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Locks with physical keys
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 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 allowing or denying entry to the cylinder. A series of pointed teeth and notches on the blade, called bittings, then allow pins 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.
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 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.
List of common locks
- Bicycle lock
- Cam lock
- Chamber lock
- Child safety lock
- Combination lock
- Cylinder lock
- Electronic lock
- Electric strike
- Magnetic lock
- Mortise lock
- Keycard lock
- Lever tumbler lock
- Chubb detector lock
- Protector lock
- Luggage lock
- Magnetic keyed lock
- Rim lock
- Time lock
Locksmithing is a traditional trade, and in most countries requires completion of an apprenticeship. The level of formal education required varies from country to country, from a simple training certificate awarded by an employer, to a full diploma from an engineering college. 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. A locksmith is 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.
Full disclosure requires that full details of a security vulnerability are disclosed to the public, including details of the vulnerability and how to detect and exploit it. The theory behind full disclosure is that releasing vulnerability information immediately results in better security. Fixes are produced faster because vendors and authors are forced to respond in order to protect their system from potential attacks as well as to protect their own image. Security is improved because the window of exposure, the amount of time the vulnerability is open to attack, is reduced. The issue of full disclosure was first raised in a 19th-century controversy over the revelation of lock-system weaknesses to the public. According to A. C. Hobbs:
A commercial, and in some respects a social doubt has been started within the last year or two, whether or not it is right to discuss so openly the security or insecurity of locks. Many well-meaning persons suppose that the discussion respecting the means for baffling the supposed safety of locks offers a premium for dishonesty, by showing others how to be dishonest. This is a fallacy. Rogues are very keen in their profession, and know already much more than we can teach them respecting their several kinds of roguery.
Rogues knew a good deal about lock-picking long before locksmiths discussed it among themselves, as they have lately done. If a lock, let it have been made in whatever country, or by whatever maker, is not so inviolable as it has hitherto been deemed to be, surely it is to the interest of honest persons to know this fact, because the dishonest are tolerably certain to apply the knowledge practically;and the spread of the knowledge is necessary to give fair play to those who might suffer by ignorance.
It cannot be too earnestly urged that an acquaintance with real facts will, in the end, be better for all parties. Some time ago, when the reading public was alarmed at being told how London milk is adulterated, timid persons deprecated the exposure, on the plea that it would give instructions in the art of adulterating milk; a vain fear, milkmen knew all about it before, whether they practiced it or not; and the exposure only taught purchasers the necessity of a little scrutiny and caution, leaving them to obey this necessity or not, as they pleased.
— A. C. Hobbs (Charles Tomlinson, ed.), Locks and Safes: The Construction of Locks. Published by Virtue & Co., London, 1853 (revised 1868).
- Robert Barron patented a double-acting tumbler lock in 1778, the first reasonable improvement in lock security.
- Joseph Bramah patented the Bramah lock in 1784. It was considered unpickable for 67 years until A.C. Hobbs picked it, taking over 50 hours.
- Jeremiah Chubb patented his detector lock in 1818. It won him the reward offered by the Government for a lock that could not be opened by any but its own key.
- James Sargent described the first successful key-changeable combination lock in 1857. His lock became popular with safe manufacturers and the United States Treasury Department. In 1873, he patented a time lock mechanism, the prototype for those used in contemporary bank vaults.
- Samuel Segal of the Segal Lock and Hardware Company invented the first jimmy-proof locks in 1916.
- Harry Soref founded the Master Lock Company in 1921 and patented an improved padlock in 1924 with a patent lock casing constructed out of laminated steel.
- Linus Yale, Sr. invented a pin tumbler lock in 1848.
- Linus Yale, Jr. improved upon his father's lock in 1861, using a smaller, flat key with serrated edges that is the basis of modern pin-tumbler locks. Yale developed the modern combination lock in 1862.
- Access control
- Associated Locksmiths of America
- Door security
- Exit control lock
- Physical security
- Rope lock
- Security door chain
- de Vries, N. Cross and D. P. Grant, M. J. (1992). Design Methodology and Relationships with Science: Introduction. Eindhoven: Kluwer Academic Publishers. p. 32.
- Ceccarelli, Marco (2004). International Symposium on History of Machines and Mechanisms. New York: Kluwer Academic Publishers. p. 43. ISBN 1402022034.
- Pulford, Graham W. (2007). High-Security Mechanical Locks : An Encyclopedic Reference. Elsevier. p. 317. ISBN 0-7506-8437-2.
- Pulford, Graham W. (2007). High-Security Mechanical Locks : An Encyclopedic Reference. Elsevier. p. 173. ISBN 0-7506-8437-2.
- "Opening an Antique Bramah Box Lock". Hygra.com. Retrieved 2012-08-15.
- "Bramah Locks". Crypto.com. Retrieved 2012-08-15.
- Phillips, Bill. (2005). The Complete Book of Locks and Locksmithing. McGraw-Hill. ISBN 0-07-144829-2.
- Alth, Max (1972). All About Locks and Locksmithing. Penguin. ISBN 0-8015-0151-2
- Robinson, Robert L. (1973). Complete Course in Professional Locksmithing Nelson-Hall. ISBN 0-911012-15-X
|Wikibooks has more on the topic of: Lock (device)|
|Wikimedia Commons has media related to: Locks|
- "Historical locks" by Raine Borg and ASSA ABLOY
- Lock Terminology
- "Picking Locks", Popular Mechanics