@article { author = {Tariq Banday, M. and A. Shah, N.}, title = {Image flip CAPTCHA}, journal = {The ISC International Journal of Information Security}, volume = {1}, number = {2}, pages = {105-123}, year = {2009}, publisher = {Iranian Society of Cryptology}, issn = {2008-2045}, eissn = {2008-3076}, doi = {10.22042/isecure.2015.1.2.4}, abstract = {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.}, keywords = {CAPTCHA,HIP,Botnet,Image CAPTCHA,Clickable CAPTCHA,CAPTCHA Security,CAPTCHA Usability}, url = {https://www.isecure-journal.com/article_39170.html}, eprint = {https://www.isecure-journal.com/article_39170_40e624cd410df4827a7d5a5120370ef0.pdf} }