Computer keyboard: Difference between revisions

Revision as of 14:44, 9 March 2023

Revision as of 15:04, 9 March 2023

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Also known as photo-optical keyboard, light responsive keyboard, photo-electric keyboard and optical key actuation detection technology.

An optical keyboard technology<ref>{{cite web |title=What is an Optical Keyboard? |url=https://www.wisegeek.com/what-is-an-optical-keyboard.htm}}</ref>{{better source|reason=user-generated content, not a [[wp:reliable source]]|date=March 2023}} utilizes [[Light-emitting diode|LEDs]] and [[Photoelectric sensor|photo sensors]] to optically detect actuated keys. Most commonly the emitters and sensors are located in the perimeter, mounted on a small [[Printed circuit board|PCB]]. The [[light]] is directed from side to side of the keyboard interior and it can only be blocked by the actuated keys. Most optical keyboards<ref>{{cite web

|title=Best Optical Keyboards

|url=https://www.gamingfactors.com/best-optical-keyboard}}</ref> require at least 2 beams (most commonly vertical beam and horizontal beam) to determine the actuated key. Some optical keyboards use a special key structure that blocks the light in a certain pattern, allowing only one beam per row of keys (most commonly horizontal beam).

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|date=21 November 2000|url=https://computer.howstuffworks.com/keyboard3.htm}}</ref>

In 1978, Key Tronic Corporation introduced keyboards with capacitive-based switches, one of the first keyboard technologies not to use self-contained switches.{{cn|date=March 2023}} There was simply a sponge pad with a conductive-coated Mylar plastic sheet on the switch plunger, and two half-moon trace patterns on the printed circuit board below. As the key was depressed, the capacitance between the plunger pad and the patterns on the PCB below changed, which was detected by integrated circuits (IC). These keyboards were claimed to have the same reliability as the other "solid-state switch" keyboards such as inductive and Hall-effect, but competitive with direct-contact keyboards. Prices of $60 for keyboards were achieved, and Key Tronic rapidly became the largest independent keyboard manufacturer.

Meanwhile, [[IBM]] made their own keyboards, using their own patented technology: Keys on older IBM keyboards<ref>{{cite web |website=SlashDot.org

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|url=http://iopscience.iop.org/book/978-0-7503-1350-6/chapter/bk978-0-7503-1350-6ch16}}</ref> (usually [[scancodes]]) that the computer's electronics can understand. The key switches are connected via the printed circuit board in an electrical X-Y matrix where a voltage is provided sequentially to the Y lines and, when a key is depressed, detected sequentially by scanning the X lines.

The first computer keyboards were for mainframe computer data terminals and used discrete electronic parts. The first keyboard microprocessor was introduced in 1972 by General Instruments, but keyboards have been using the single-chip [[Intel 8048|8048]] [[microcontroller]] variant since it became available in 1978.{{cn|date=March 2023}} The keyboard switch matrix is wired to its inputs, it converts the keystrokes to key codes, and, for a detached keyboard, sends the codes down a serial cable (the keyboard cord) to the main processor on the computer motherboard. This serial keyboard cable communication is only bi-directional to the extent that the computer's electronics controls the illumination of the caps lock, num lock and scroll lock lights.

One test for whether the computer has crashed is pressing the caps lock key. The keyboard sends the key code to the [[Device driver|keyboard driver]] running in the main computer; if the main computer is operating, it commands the light to turn on. All the other indicator lights work in a similar way. The keyboard driver also tracks the Shift, alt and control state of the keyboard.

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Keystroke logging can be achieved by both hardware and software means. Hardware key loggers are attached to the keyboard cable or installed inside standard keyboards. Software keyloggers work on the target computer's operating system and gain unauthorized access to the hardware, hook into the keyboard with functions provided by the OS, or use remote access software to transmit recorded data out of the target computer to a remote ___location. Some hackers also use wireless keylogger sniffers to collect packets of data being transferred from a wireless keyboard and its receiver, and then they crack the encryption key being used to secure wireless communications between the two devices.

[[Spyware|Anti-spyware]] applications are able to detect many keyloggers and cleanse them. Responsible vendors of monitoring software support detection by anti-spyware programs, thus preventing abuse of the software. Enabling a [[Firewall (computing)|firewall]] does not stop keyloggers per se, but can possibly prevent transmission of the logged material over the net if properly configured. [[Network monitoring|Network monitors]] (also known as reverse-firewalls) can be used to alert the user whenever an application attempts to make a network connection. This gives the user the chance to prevent the keylogger from "[[phoning home]]" with his or her typed information. Automatic form-filling programs can prevent keylogging entirely by not using the keyboard at all. Historically, most keyloggers could be fooled by alternating between typing the login credentials and typing characters somewhere else in the focus window.<ref>{{cite web |url=http://cups.cs.cmu.edu/soups/2006/posters/herley-poster_abstract.pdf |title=How To Login From an Internet Cafe Without Worrying About Keyloggers |last1=Herley |first1=Cormac |last2=Florencio |first2=Dinei |publisher=Microsoft Research, Redmond |date=2006 |url-status=dead |archive-url=https://web.archive.org/web/20170808070236/http://cups.cs.cmu.edu/soups/2006/posters/herley-poster_abstract.pdf |archive-date=8 August 2017 |df=dmy-all |access-date=10 September 2008 }}</ref>{{better source|reason=I doubt that this is still true. Needs a later source.|date=March 2023}}

Keyboards are also known to emit electromagnetic signatures that can be detected using special spying equipment to reconstruct the keys pressed on the keyboard. Neal O'Farrell, executive director of the Identity Theft Council, revealed to InformationWeek that "More than 25 years ago, a couple of former spooks showed me how they could capture a user's ATM PIN, from a van parked across the street, simply by capturing and decoding the electromagnetic signals generated by every keystroke," O'Farrell said. "They could even capture keystrokes from computers in nearby offices, but the technology wasn't sophisticated enough to focus in on any specific computer."<ref>{{cite web|url=http://www.informationweek.com/security/vulnerabilities-and-threats/6-tips-to-secure-webcams-stop-keyloggers/d/d-id/1113012|title=6 Tips To Secure Webcams, Stop Keyloggers|work=Dark Reading|date=10 December 2013|url-status=live|archive-url=https://web.archive.org/web/20131230233248/http://www.informationweek.com/security/vulnerabilities-and-threats/6-tips-to-secure-webcams-stop-keyloggers/d/d-id/1113012|archive-date=30 December 2013|df=dmy-all}}</ref>