CAPTCHA, or “Completely Automated Public Turing” is a type of reaction test generally used in the computing environment to establish whether the user is human or not. The term includes all technological tools used to distinguish humans from computers during online interaction.
The main purpose of CAPTCHA text is to prevent automatic computer processes from abusing e-mail systems by repeatedly entering passwords or from overloading or causing security problems on network services.
The most common example of CAPTCHA can be seen below and consists of a series of distorted or cross-hatched letters and numbers users have to retype. These distorted letters hidden in letters are easily recognised by humans, but computers find it difficult.
Unfortunately computers and CAPTCHA code hacking algorithms are becoming more sophisticated and subsequently the CAPTCHA codes also become more distorted and difficult for people to recognise.
The term was first used in 2000 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper of the Carnegie Mellon University and John Langford of IBM. The most popular CAPTCHA was invented by Mark D. Lillibridge, Martin Abadi, Krishna Bharat and Andrei Z. Broder. This type of CAPTCHA prompts the user to retype letters displayed on a distorted image, sometimes also overshadowed by a series of other letters or numbers on the screen.
Seeing that this test, unlike the standard Turing test which is conducted by a person, is performed by a computer, it is often referred to as a reverse Turing test.
The CAPTCHA identification process for users has been heavily criticised, especially by disabled users, but also by other users who feel that their daily work is slowed down by distorted illegible words, even for people without disabilities.
Read more on CAPTCHA on the official website.
[SOURCE: http://www.webopedia.com/DidYouKnow/_index.asp and www.wikipedia.org]
CAPTCHA, of “Completely Automated Public Turing” is `n tipe reaksietoets gebruik in die rekenaaromgewing om vas te stel of die gebruiker `n persoon is. Die term omvat alle tegnologiese middele wat gebruik word om mense van rekenaars te onderskei gedurende aanlyn interaksie.
Die hoofdoel van CAPTCHA teks is om te verhoed dat outomatiese rekenaarprosesse e-pos stelsels misbruik deur herhaaldelik wagwoorde in te tik, of om onnodige stremming of sekuriteitsprobleme te veroorsaak vir netwerkdienste.
Die algemeenste voorbeeld van CAPTCHA kan onder gesien word en behels dat die gebruiker `n reeks verwronge of kruisluik (“cross-hatched”) letters en syfers herken en tik. Mense kan verwronge letters wat weggesteek word in `n beeld maklik herken, terwyl rekenaars dit besonder moeilik vind.
Ongelukkig word rekenaars en algoritmes wat CAPTCHA-kodes kraak meer gesofistikeerd en gevolglik raak die CAPTCHA-kodes ook meer verbuig en moeiliker vir mense om te herken. Sekuriteitspesialiste is voortdurend opsoek na nuwe CAPTCHA tegnieke wat robot-gedrewe misbruik kan voorkom sonder om die gewone gebruiker te benadeel.
Die term is die eerste keer in 2000 deur Luis von Ahn, Manuel Blum, Nicholas J. Hopper van die Carnegie Mellon Universiteit en John Langford van IBM gevestig. Die algemeenste CAPTCHA is die eerste keer uitgevind deurMark D. Lillibridge, Martin Abadi, Krishna Bharat en Andrei Z. Broder. Dié tipe CAPTCHA vra van die gebruiker om die letters van `n verwronge beeld, wat soms ook oorskadu word deur `n reeks letters of syfers op die skerm, weer te gee.
Omdat die toets, anders as die standaard Turing-toets wat deur `n persoon gefasiliteer word, deur `n rekenaar uitgevoer word, word daarna soms verwys as `n omgekeerde Turing-toets.
Hierdie identifikasieproses vir gebruikers is al hewiglik gekritiseer, veral deur gestremde persone, maar ook deur ander gebruikers wat voel dat hul daaglikse take belemmer word deur verwronge woorde wat onleesbaar is, selfs vir mense met geen gestremdhede.
Lees meer oor CAPTCHA op hulle amptelik webwerf
[BRON: http://www.webopedia.com/DidYouKnow/_index.asp en www.wikipedia.org]
