CAPTCHAs have become a standard security mechanism that are used to deter automated abuse of online services intended for humans. However, many existing CAPTCHA schemes to date have been successfully broken. As such, a number of CAPTCHA developers have explored alternative methods of designing CAPTCHAs. 3D CAPTCHAs is a design alternative that has been proposed to overcome the limitations of tr...

We propose a new scheme of attack on the Microsoft’s ASIRRA CAPTCHA which represents a significant shortcut to the intended attacking path, as it is not based in any advance in the state of the art on the field of image recognition. After studying the ASIRRA Public Corpus, we conclude that the security margin as stated by their authors seems to be quite optimistic. Then, we analyze which of the...

The increasing use of smart phones, tablets, and other mobile devices poses a significant challenge in providing effective online security. CAPTCHAs, tests for distinguishing human and computer users, have traditionally been popular; however, they face particular difficulties in a modern mobile environment because most of them rely on keyboard input and have language dependencies. This paper pr...

problems, namely,a novel family of graphical password systems built on top of Captcha Zoo is a Captcha scheme which uses 3D models of horse and dog. mathematical concept related to 3D password, applications of scheme etc. Moreover, Pass. Point – is a recall-based graphical password schema, where a (2) Fawaz A. Alsulaiman and Abdulmotaleb El Saddik, “A Novel 3D. Graphical. also offers a novel ap...

Improvements in image understanding technologies are making it possible for computers to pass traditional CAPTCHA tests with high probability. This suggests the need for new kinds of tasks that are easy to accomplish for humans but remain difficult for computers. In this paper, we introduce Fluency CAPTCHA (FluTCHA), a novel method to distinguish humans from computers using the fact that humans...

Captcha (Completely Automated public Turing test to tell Computers and Humans Apart) system is used to verify whether a user is human or computer program. It’s also known as human Interactive Proof (HIP) and based upon Artificial Intelligence. Captcha is a program that protects websites from web-bots by generating tests that computer cannot pass but human can pass .This paper comprise introduct...

In this paper, we firstly introduce that CAPTCHA technology development and the various type of reading CAPTCHA, sound CAPTCHA, graph CAPTCHA at present. The second, we build one kind of the Chinese CAPTCHA model. The third, a new Chinese CAPTCHA system based on AJAX is proposed, which proceed to generate character characteristic based random problem and answer. On its performance, we show that...

The landscape of the World Wide Web today consists of a vast amount of services. While most of them are offered for free, the service providers prohibit their malicious usage by automated scripts. To enforce this policy, Captchas have emerged as a reliable method to setup a Turing test to distinguish between human and computers. Image recognition Captchas as one type of Captchas promise high hu...