O-CAPTCHA - An Orientation Puzzle

Malicious applications or bots massively contaminate the authenticity, and seriously damage the integrity of online valuable resources. CAPTCHAs prove to be excellent tool for protecting precious online resources. The reason for the success of CAPTCHAs is their simplicity in usability. CAPTCHAs schemes are evaluated by two characteristics i.e. usability and robustness. This paper presents a novel CAPTCHA scheme called 'O-CAPTCHA' which provides user with a text based orientation challenge. It is easier for human being to judge the proper shape of Letters/Alphabets so they can complete the challenge quickly. The Proposed method is tested on both Smartphone devices and desktop computers. Extensive experimentation is performed on the proposed method in terms of usability analysis and invincibility of the scheme against automated Bot attacks. Proposed orientation layer can be incorporated in any modern text based CAPTCHA scheme making them stealthier and a tough nut to crack for the bots without compromising their usability.