Types Of CAPTCHAs Research Articles

Research of the chinese CAPTCHA system based on AJAX

In this paper, we firstly introduce that CAPTCHA technology development and the various type of reading CAPTCHA, sound CAPTCHA, graph CAPTCHA at present. The second, we build one kind of the Chines...

Is it human or computer? Defending e-commerce with Captchas

A Captcha - a completely automatic public Turing test to tell computers and humans apart - is a test that humans can pass but computer programs cannot; such tests are becoming key to defending e-commerce systems. By using a Captcha, for example, IT systems can permit only real people-rather than a spammer's script-to create a free e-mail account. This article explains the various types of Captchas and discusses their strengths and weaknesses as a security measure. It also lists sources for more information on the formal research into Captchas.