A Novel Captcha Study based on Image Selection Scheme

Captcha is a popular real user detection or autobot/robot rejection technique used in websites for Desktops. Captcha is also in use in some of the mobile websites. Captcha are difficult to read on the smartphone and portable computer screens. Users stuck in zooming in/zooming out while reading and filling the captcha and other required fields. Old aged users feel it more difficult to view and type the catpcha. So, there is a strong need of image based easy captcha-like technique to detect the real users and to avoid the autobot/robot tools, which are used to exploit the website databases. In this research we have proposed a visual/graphical alternate to captcha. In this research, we are proposing the development of a new captcha-like technique which will facilitate the user to enter a graphical captcha instead of text based captcha. Users will see a full image and a chunk from the image (sub-image). User will have to tap on the image area, which matches the chunk (sub-image). Further, the system will crop the image to that particular area in some particular size, which will be then forwarded to the server for the real-user authentication. Server side will match the chunk with the cropped image (which is a user input). If chunk is matched with the cropped image, the user will be marked a real user, otherwise a new captcha-like will be sent to the user for re-authentication. If user will fail for a fixed number of times, the server-side will mark the user as a autobot and will block the user for some time.