CAPTCHAs exploit the gap in the ability between a human and a machine to understand the semantics of specific multimedia content, with vast applications in computer security. In this paper we compare two techniques in automated CAPTCHA solving for text-based CAPTCHA schemes, i.e., classification based on the Vector Space Model (VSM) versus a popular Optical Character Recognition (OCR) engine. F...

Information and computer security is supported by passwords. Password is the principal part of authentication process. The traditional authentication method is to use text-based password which is also called alphanumeric password. But it has significant drawbacks. So to overcome vulnerabilities of this traditional password scheme a graphical password scheme is developed. But major drawback of g...

-We are in the era of internet and depend on it for every necessary requirement. It is the tendency of the some human to have destructive approach rather than having constructive approach. Among the abuse and misuse of internet, the distributed denial of service attack (DDOS) is the most hectic one. People have carried out various method of mitigation using the CAPTCHA (Completely Automated Pub...

Evolution in the world of internet has given rise to several online attacks and the most common attack is phishing. Victims are tricked into providing such information by a combination of spoofing techniques and social engineering. Phishing is an attempt by an individual or a group to acquire sensitive information such as usernames, passwords, and credit card details from unsuspecting victims. ...

As one of the advanced Completely Automated Public Turing tests to tell Computers and Humans Apart (CAPTCHAs), the CAPTCHA using mental rotation has been proposed. Mental rotation is an advanced human-cognitiveprocessing ability to rotate mental representations of “one” single 2D/3D object. However, as have already been reported, the mental rotation CAPTCHA can be overcome by pattern matching a...

Phishing is an attempt by an individual or a group to thieve personal confidential information such as passwords, credit card information etc from unsuspecting victims for identity theft, financial gain and other fraudulent activities. In this paper we have proposed a new approach named as "A Novel Antiphishing framework based on visual cryptography" to solve the problem of phishing. Here an im...

In this paper, we propose a novel image-based completely automated public turing test to tell computers and humans apart (CAPTCHA) that relies on detecting human faces to provide an additional layer of security in web-based services. Face images were selected from the CMU face database and subjected to different types of distortions at different intensity levels to make the automatic face detec...

Abstract: CAPTCHA-Systeme sind weit verbreitete Schutzsysteme, um auf OnlinePlattformen menschliche Benutzer von automatischen Bots zu unterscheiden. Dabei kommen verschiedene Varianten zum Einsatz, die sich in Art und Interaktionsmodus sowie im Schwierigkeitsgrad der Lösung unterscheiden. In der vorliegenden Studie werden Kriterien der Benutzbarkeit von CAPTCHA-Systemen aufgestellt. Zudem werd...

Research on CAPTCHA has led CAPTCHA design into adopting almost exclusively graphical implementations that deal mostly with character recognition. This has reached an exhaustion point, where new approaches are vital to the survival of the technique. This paper discusses the early stages of a research that intends to solve the open problem of a CAPTCHA in the text domain offering, this way, inno...

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...