Bots are programs that crawl through the web site and make auto registrations. CAPTCHAs, using Latin script, are widely used to prevent automated bots from abusing online services on the World Wide Web. However, many of the existing English based CAPTCHAs have some inherent problems and cannot assure the security of these websites. This paper proposes a method that focuses on the use of Arabic ...

Text CAPTCHA has been an effective means to protect online systems from spams and abuses caused by automatic scripts which pretend to be human beings. However, nearly all the Text CAPTCHA designs in nowadays are based on English characters, which may not be the most userfriendly option for non-English speakers. Therefore, under the background of globalization, there is an increasing interest in...

CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart) is a simple test that is easy for humans but extremely difficult for computers to solve. CAPTCHA has been widely used in commercial websites such as web-based email providers, TicketMaster, GoDaddy, and Facebook to protect their resources from attacks initiated by automatic scripts. By design, CAPTCHA is unable...

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...

CAPTCHA is an important technology to prevent auto-script attack. Currently most of the CAPTCHA systems are text based, which firstly distort, rotate different characters and then use some obfuscation, aiming to make the text difficult to be recognized by autoscript while still can be learnt easily by real users. However, such kind of CAPTCHA schema either too simple, which can be attacked easi...

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...

Video CAPTCHA improves the usability while reducing the attack success rate compared to a conventional text-based CAPTCHA. However, it remains vulnerable to OCR attacks. Thus, we proposed to use inpainting algorithms to remove the contained text in the video frames, so that the OCR success rate can be reduced without introducing unwanted artifacts that displease the endusers. We implemented Ber...

CAPTCHA is a technology which has its base in a test called the Turing Test. Alan Turing, proposed this test as a way to examine whether or not machines can think or appear to think like humans. The main purpose of a CAPTCHA is to block form submissions from spam botsthat is automated scripts. Various types of CAPTCHAs are used, which mostly requires users to enter the strings of characters tha...