A New Scheme for Mobile Based CAPTCHA Service on Cloud

CAPTCHAs are popularly used techniques to distinguish humans and automated applications. Such techniques are often useful in banking transactions, email creation, online surveys, data downloads etc. Starting from a very primitive stage of providing the users with a simple alphabetical string to asking using to do complex calculations, CAPTCHAs have come a long way in terms of sophistication of human-bot distinction. However in this process, these CAPTCHAs have lost their human friendliness, either because of the noise being added to the CATPCHA tests or because of the complications of the challenges thrown to the user resulting in bad experience. The traditional CAPTCHAs also fail to take into account the unique needs of the ubiquitous mobile devices. These mobile devices have few limitations like small display area, limited display resolution, color combinations of the display, processing power etc. Also, they have unique advantages of touch sensitive input devices, voice inputs, voice outputs etc. In this paper, we present a scheme for a CAPTCHA service on Cloud, which is specific to mobile application. We duly consider the need of usability and presentation that is required for a mobile device in our implementation. The proposed CAPTCHA framework offers scalable and flexible implementation opportunities in many verticals and domains. Another unique feature of our framework is that we provide the facility for distributed verification. This greatly improves the efficiency at the CATPCHA generation as well as reduces the response time for the user authentication as human.