We systematically study the design of image recognition CAPTCHAs (IRCs) in this paper. We first review and examine all IRCs schemes known to us and evaluate each scheme against th...
Bin B. Zhu, Jeff Yan, Qiujie Li, Chao Yang, Jia Li...
We present WebSOS, a novel overlay-based architecture that provides guaranteed access to a web server that is targeted by a denial of service (DoS) attack. Our approach exploits t...
William G. Morein, Angelos Stavrou, Debra L. Cook,...
Efforts to defend against automated attacks on e-commerce services have led to a new security protocol known as a CAPTCHA, a challenge designed to exploit gaps in the perceptual a...
Reverse Turing tests, or CAPTCHAs, have become an ubiquitous defense used to protect open Web resources from being exploited at scale. An effective CAPTCHA resists existing mechan...
Marti Motoyama, Kirill Levchenko, Chris Kanich, Da...
In this paper, we propose a new form of image-based CAPTCHA we term "scene tagging". It tests the ability to recognize a relationship between multiple objects in an imag...