Seminar Report And PPT On CAPTCHA
The article presents a seminar topic on CAPTCHA. Whenever you register or login into a website, a rectangle distorted image is shown that displays some quite unreadable text on it. The computer asks to enter the displayed text in a text input that is called CAPTCHA. CAPTCHA stands for “Computer Automated Turning Test to Tell Computer and Human Apart”.
Why CAPTCHA is used for: CAPTCHA is a type of security test that is taken by the computer system before registering the user to get the proof of human that means the registrant is an alive human not a programmed bot or spam. Because the internet spammers develop some programmer bots or spam that read the structure of all kind or forms (Common Forms) on the internet such as forum registration page, wordpress comment forum etc and then register on them by bypassing all the validations using fake data. This is done by spammers for advertising their products or some other illegal activities. CAPTCHA prevents this kind of automatic registration or login process because by using CAPTCHA the user must enter the CAPTCHA code produced on distorted image in the input box, otherwise the registration will not succeed. Alive human can see the code and enters easily but the programmed bots have neither eyes nor ears and so they can’t bypass this CAPTCHA field.
How CAPTCHA works: To make the form CAPTCHA enabled, a CAPTCHA script is developed. In this script, A random string is generated by specific function and the generated code is used at two places. One side the random generated CAPTCHA code is stored in a session CAPTCHA variable and on other side the code is sued to produce a image by using a text to image converter script. This image is visible to the user and asks to enter the CAPTCHA code in text input. When the code is entered and form is submitted, the CAPTCHA code and session CAPTCHA variables are matched. If both are same the form goes for further processing otherwise the page again refreshes and new code and CAPTCHA image is generated. Today the audio version of CAPTCHA is also available by which if you are unable to read the text on image, you can hear it and then enter the code. Full Seminar Report on CAPTCHA is given in the attachment.