Kill switch

This article is about the security device. For other uses, see Kill switch (disambiguation).

An unprotected kill switch.

A kill switch (also called an e-stop) is a security measure used to shut off a device in an emergency situation in which it cannot be shut down in the usual manner. Unlike a normal shut down, which shuts down all systems naturally and turns the machine off without damaging it, a kill switch is designed to completely abort the operation at all costs, and be configured so that it is quick to operate, and relatively obvious to someone other than the usual operator. It might have some protection to prevent accidental operation, but which can be quickly moved out of the way. Often, they are used to protect people from sustaining an injury or being killed, in which case damaging the machine may be considered to be acceptable.

Physical world applications

A similar system, usually called a dead man's switch (for other names, see alternative names), as its name suggests, is a device intended to stop a machine in case the human operator becomes incapacitated, and is a form of fail-safe. They are commonly used in locomotives, tower cranes, freight elevators, lawn mowers, tractors, jet skis, outboard motors, snowblowers and snowmobiles.

Vehicles

If it is used to shut down vehicles and machinery if the operator loses control or is ejected, then it is called dead man's switch. A common example of this would be the kill switches used by boaters wherein a cord connects the kill switch to the operator (usually by their life jackets), and if the operator is thrown overboard in an accident, the cord will pull the switch and immediately shut down the vessel's engine.

NASCAR (National Association for Stock Car Auto Racing) requires all their stock cars to be equipped with a steering wheel-mounted kill switch, in case the accelerator pedal sticks and the driver needs to shut down the engine.

Kill switches are also used on land vehicles as an anti-theft device and as an emergency power off. Such devices are often equipped into bait cars and set up so that observing police can trigger the switch remotely.

Machinery

A kill switch is also used for gasoline pumps or any other device that pumps large amounts of explosive or flammable chemicals. There is commonly a single kill switch for all pumps at a pumping station.

Musical instrument

An electric musical instrument, such as a guitar or bass guitar, may have a kill switch. It is used infrequently but most commonly in heavy metal music. Contrary to popular belief, a kill switch doesn't break the circuit but works by switching between the hot signal from a pick-up and the ground signal. A typical way of achieving this is (on a guitar with a volume control for each pick-up) by turning down the volume on one of the pick-ups then alternating the pick-up selector switch between that pick-up and one with the volume turned all the way up. They are sometimes used when a singer doubles as a guitar player and isn't playing or sometimes used as an effect during a song. Tom Morello of Rage Against the Machine and Audioslave, Buckethead (for example, "Jordan" and "Circarama" ), Ace Frehley of Kiss (such as in the intro to the song "Cold Gin" from the Kiss Alive! album and during his concert solos documented in numerous 1970s video bootlegs), and Jonny Greenwood of Radiohead are well known for their use of the kill switch. Jack White uses a kill switch during some of his performances and in songs like Icky Thump. Some guitarists fashion their own kill switches. These are sometimes rather crude but still just as effective as one made by a professional.

Gym

Treadmills often use a safety key that the runner clips to his waist, and if he falls or trips, the safety key is pulled out, and the machine stops immediately. In other cases treadmills use a more traditional kill switch, often mounted towards the rear of one of the hand-railings.

Information Technology

Computer software

The concept of "kill switch" may also be applied to software as an anti-piracy feature, most notably in Windows Vista. It renders the software essentially useless to users running what is determined by the software author to be an illegitimately obtained, or pirated, copy. In the example of Microsoft Windows, the company developed a verification tool named Windows Genuine Advantage, that originally activated a kill switch, or reduced functionality mode, on what Microsoft's mandatory software's deemed to be an unlicensed copy of the operating system. Software kill switches have been shown to have varying degrees of success, as false positives have been known to occur, prompting some vendors like Microsoft to "turn off" the software kill switch in response to market pressure.

There is some anecdotal evidence that some software vendors install kill switches in their software to enforce planned obsolescence, also known as a forced upgrade. This can cause considerable disruption in said customer's business functions.

Computer security policy

On June 19, 2010, Senator Joe Lieberman (I-CT) introduced a bill called "Protecting Cyberspace as a National Asset Act of 2010" (full text in pdf), which he co-wrote with Senator Susan Collins (R-ME) and Senator Thomas Carper (D-DE). If signed into law, this controversial bill, which the American media dubbed the "Kill switch bill", would grant the President emergency powers over the Internet. Other parts of the bill focus on the establishment of an Office of Cyberspace Policy and on its missions, as well as on the coordination of cyberspace policy at the federal level. Interviewed by Candy Crowley on CNN's State of the Union, Lieberman claimed that "a cyber attack on America [could] do as much or more damage [...] by incapacitating our banks, our communications, our finance, our transportation, as a conventional war attack". If national security were to be severely threatened by a cyber attack, broadband providers, search engines, software firms and other major players in the Telecommunications/Computer/Internet industry could be required to immediately comply and implement any emergency measure taken; for most of the month of June, media coverage of the bill insisted on this so-called 'Kill switch' provision, said to be included in the bill .

However, after this proposal became controversial, in large part due to concerns that it granted too much power to the President and threatened freedom of speech, all three co-authors of the bill issued a statement claiming that instead, the bill "[narrowed] existing broad Presidential authority to take over telecommunications networks", and Senator Lieberman contended that the bill did not seek to make a 'Kill switch' option available ("the President will never take over -- the government should never take over the Internet"), but instead insisted that serious steps had to be taken in order to counter a potential mass scale cyber attack. "Right now, China, the government, can disconnect parts of its Internet in a case of war. We need to have that here, too," he said on Candy Crowley's State of the Union on CNN. This remark sparked another controversy, and led Comedy Central's Jon Stewart to make fun of Senator Lieberman for bringing up the example of China, which is notorious for its lack of regard for freedom of speech, on his satirical program The Daily Show with Jon Stewart.

Section 249 of the bill states that "the President may issue a declaration of a national cyber emergency to covered critical infrastructure," in which case a response plan is implemented^[1]. This plan shall consist of "measures or actions necessary to preserve the reliable operation, and mitigate or remediate the consequences of the potential disruption, of covered critical infrastructure". Said measures should "represent the least disruptive means feasible to the operations of the covered critical infrastructure" and "shall cease to have effect not later than 30 days after the date on 4 which the President issued the declaration of a national cyber emergency" unless the President seeks to extend them, with the approval of the Director of the Office of Cyberspace Policy established by the bill^[2].

See also

• Emergency stop