In this paper we present a new CAPTCHA system (Completely Automated Turing Test To Tell Computers and Humans Apart). This proposal, SemCAPTCHA, is motivated by an increasing number of broken OCR-based CAPTCHA systems and it is based not only on text recognition but also on text understanding. We describe SemCAPTCHA from both user’s perspective and system’s perspective and compare it to some cur...

CAPTCHA is a completely automated program designed to distinguish whether the user is a computer or human. As the problems of Internet security are worsening, it is of great significance to do research on CAPTCHA. This article starts from the recognition of CAPTCHAs, then analyses the weaknesses in its design and gives corresponding recognition proposals according to various weaknesses, finally...

The malware attacks attempt to deplete the cloud services with bogus request which is a major threat in cloud. A mechanism to intensify the login security in cloud is suggested. The concept of CaPGP – CAPTCHA as Puzzle and Graphical Password is introduced because CAPTCHA is one way to discriminate human and malware apart. The computations at the client side are made intensive than on the server...

In this paper we present a new CAPTCHA system (Completely Automated Turing Test To Tell Computers and Humans Apart). The proposal of SemCAPTCHA is motivated by an increasing number of broken OCR-based CAPTCHA systems and it is based not only on text recognition but also on text understanding. We describe both, the user’s and the system’s perspective of SemCAPTCHA and compare it with some curren...

We argue that a set of usability heuristics are needed for easy and quick evaluation of Captchas implementations. With this set of heuristics we contribute to sustain the Captcha Mantra: “Easy for humans, hard for machines”. In particular, the usability of Captcha schemes change radically when utilized on mobile environments. We are developing a set of heuristics for use by practitioners wishin...

We present STE3D-CAP (pronounced as “steed-cap” /'stidkæp/), a text-based CAPTCHA that is built from stereoscopic 3D images. This is a completely new direction in CAPTCHA techniques. Our idea is to incorporate stereoscopic 3D images in order to present the CAPTCHA challenge in 3D, which will be easy for humans to read (as the text stands out in the 3D scene) but hard for computers. The main ide...

Completely Automatic Public Turing test to tell Computers and Humans Apart (CAPTCHA) is a HIP (Human interactive Proof) system. CAPTCHAs are used to improve the security of Internet based applications in order to ensure that a web based application which is intended to be used by a human being is not maliciously used by Artificially Intelligent programs called bots. As the current CAPTCHA metho...

An automated public Turing test to distinguish between computers and humans known as CAPTCHA is a widely used technique on many websites to protect their online services from malicious users. Two fundamental aspects of captcha considered in various studies in the literature are robustness and usability. A widely accepted standard benchmark, to guide the text-based captcha developers is not yet ...

CAPTCHAs are essentially challenge-response tests that are used to distinguish whether a user is a human or a computer. To date, numerous CAPTCHA schemes have been proposed and deployed on various websites to secure online services from abuse by automated programs. However, many of these CAPTCHAs have been found to suffer from design flaws that can be exploited to break the CAPTCHA. Hence, the ...