Abstract CAPTCHA, Completely Automated Public Turing test to tell Computers and Humans
Apart, is widely used as a security mechanism to classify human and computer. This security …

Captcha challenges have become the most widely used techniques to deter the misuse of
services on the Internet. The majority of current Captcha schemes are principally based on …

Designing a CAPTCHA possessing the property of a sweet spot is always a challenge. Text-
based CAPTCHAs are popular among websites. The history of text-based schemes shows …

Online fraud often involves identity theft. Since most security measures are weak or can be
spoofed, we investigate a more nuanced and less explored avenue: behavioral biometrics …

CAPTCHAs (Completely Automated Public Turing Test to Tell Computers and Humans
Apart) are one of the most widely used authentication mechanisms that help to prevent …

Despite some technical and conceptual criticism on the CAPTCHA and its claimed
effectiveness, such human interaction proofs (HIPs) are still in the centre of attention. With …

This article describes an emerging direction in the intersection between human–computer
interaction and cognitive science: the use of cognitive models to give insight into the …

TAPCHA is a universal CAPTCHA scheme designed for touch-enabled smart devices such
as smartphones, tablets and smartwatches. The main difference between TAPCHA and …