Captcha Demo

A Captcha is a type of challenge-response test used to determine whether or not the user is human. A common type of captcha requires that the user type the letters of a distorted, sometimes with the addition of obscured sequence of letters or digits that appears in an image.

Captcha is an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart" and was coined in 2000 by a few computer scientist at Carnegie Mellon University and IBM. However, Alan Turning described challenge-response tests in a 1950's paper. While the modern day Captcha was developed at AltaVista in 1997 to prevent bots from adding URLs to the search engine.

In this demo we're going to use ColdFusion to build us a 235x60 pixel captcha image, of 5-7 lowercase letters, with minimal distortion and noise (all of which is fully configurable). Then we're going to send your challenge response to the server via an Ajax call. The server will validate your input and reply with a yes/no response. From that we display an alert box with audio feedback as well. However in a normal application, the form would navigate to the next page, usually step two of some sort of signup process or contact form.

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