Improved Captcha Method

Abstract

A CAPTCHA is a program that can tell whether its user is a human or a computer. CAPTCHAs are used by many websites to differentiate between the bots (automated program) and the human. The main motive behind using the CAPTCHA is to prevent abuse from "bots," or automated programs usually written to generate spam. The CAPTCHA basically uses images in distorted form that is difficult to read by the bots but they can be read by the human being easily. The websites which provide free services to the users some anonymous user can make false enrollment on the websites with the help of automated computer program. CAPTCAHS are used to prevent the false enrollment. One of the CAPTCHA methods is Collage CAPTCHA. In this method some shapes are shown with distortion and the user is asked to choose a specific object In this paper we increase the resistance of this method to attacks. For this purpose, we show some objects on the left of the screen and some of the objects on the right side of the screen which contain the name corresponding to the images shown on the left side of the screen. Now we ask the user to choose object on the left side and a specific image (containing word) on the right side of the screen. The image on the right side of the screen contains the name of the image. After this user is asked to enter the name of the image in a text box shown below the two images. The user will be passed the test if he chooses the two similar objects correctly and then he/she has entered the name of the image correctly in the text box. In this method because the computer program should also recognize the similar object on the right side and need to enter the name of the image in text box ,the possibility of passing the test by computer is more reduced.