A CAPTCHA is a challenge-response test often used on the Web to determine whether a Web site’s visitor is a human or an automated program (so called bot). Existing and widely used CAPTCHA schemes are based on visual puzzles that are hard to solve on mobile devices with a limited screen. We propose to leverage movement data from hardware sensors to build a CAPTCHA scheme suitable for mobile devi...

CAPTCHAs are a widely deployed mechanism for ensuring that a web site user is a human, and not a software agent. They ought to be relatively easy for a human to solve, but hard for software to interpret. Most CAPTCHAs are visual, and this marginalises users with visual impairments. A variety of audible CAPTCHAs have been trialled but these have not been very successful, largely because they are...

Many web-based services such as email, search engines, and polling sites are being abused by spammers via computer programs known as bots. This problem has bred a new research area called Human Interactive Proofs (HIP) and a testing device called CAPTCHA, which aims to protect services from malevolent attacks by distinguishing bots from human users. In the past decade, researchers have focused ...

We explore the robustness and usability of movingimage object recognition (video) captchas, designing and implementing automated attacks based on computer vision techniques. Our approach is suitable for broad classes of moving-image captchas involving rigid objects. We first present an attack that defeats instances of such a captcha (NuCaptcha) representing the state-ofthe-art, involving dynami...

As protection of web applications are getting more and more important every day, CAPTCHAs are facing booming attention both by users and designers. Nowadays, it is well accepted that using visual concepts enhance security and usability of CAPTCHAs. There exist few major different ideas for designing image CAPTCHAs. Some methods apply a set of modifications such as rotations to the original imag...

Image CAPTCHA, aiming at effectively distinguishing human users from malicious script attacks, has been an important mechanism to protect online systems from spams and abuses. Despite the increasing interests in developing and deploying image CAPTCHAs, the usability aspect of those CAPTCHAs has hardly been explored systematically. In this paper, the universal design factors of image CAPTCHAs, s...

The Most of the protected resources are based on difficult math issues. How to use hard Artificial Intelligence issues for protection is growing as an exciting new paradigm, but has been under-explored. We apply a new protection resource are based on hard personal Artificial Intelligence issues. CARP also provides a new technique to address the famous image hotspot issue in popular graphical pa...

Facial/voice-based authentication is becoming increasingly popular (e.g., already adopted by MasterCard and AliPay), because it is easy to use. In particular, users can now authenticate themselves to online services by using their mobile phone to show themselves performing simple tasks like blinking or smiling in front of its built-in camera. Our study shows that many of the publicly available ...

Recently, with the spread of online services involving websites, attackers have opportunity to expose these malicious actions. To protect services, A Completely Automated Public Turing Test Tell Computers and Humans Apart (CAPTCHA) is a proposed technique. Since many Arabic countries developed their in Arabic, text-based CAPTCHA has been introduced improve usability for users. Moreover, there e...