Image Flip CAPTCHA

The massive and automated access to web resources through robots has made it essential for web service providers to make some conclusion about whether the user is a human or a robot. a human interaction proof (hip) like completely automated public turing test to tell computers and humans apart (captcha) offers a way to make such a distinction. captcha is a reverse turing test used by web service providers to secure human interaction assumed services from web bots. several web services that include and are not limited to free e-mail accounts, online polls, chat rooms, search engines, blogs, password systems, etc. use captcha as a defensive mechanism against automated web bots. in this paper, we present a new clickable image-based captcha technique. the technique presents user with a captcha image composed of several sub-images. properties of the proposed technique offer all of the benefits of image-based captchas; grant improved security than that of usual ocr-based techniques, consume less web page area than most of image-based techniques and at the same time improve the user-friendliness of the web page.