The ASIRRA CAPTCHA [6], recently proposed at ACM CCS 2007, relies on the problem of distinguishing images of cats and dogs (a task that humans are very good at). The security of AS...
CAPTCHAs protect online resources and services from automated access. From an attacker’s point of view, they are typically perceived as an annoyance that prevents the mass creat...
Manuel Egele, Leyla Bilge, Engin Kirda, Christophe...
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...
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...