69 research outputs found
A Framework for Devanagari Script-based Captcha
Human Interactive Proofs (HIPs) are automatic reverse Turing tests designed
to distinguish between various groups of users. Completely Automatic Public
Turing test to tell Computers and Humans Apart (CAPTCHA) is a HIP system that
distinguish between humans and malicious computer programs. Many CAPTCHAs have
been proposed in the literature that text-graphical based, audio-based,
puzzle-based and mathematical questions-based. The design and implementation of
CAPTCHAs fall in the realm of Artificial Intelligence. We aim to utilize
CAPTCHAs as a tool to improve the security of Internet based applications. In
this paper we present a framework for a text-based CAPTCHA based on Devanagari
script which can exploit the difference in the reading proficiency between
humans and computer programs. Our selection of Devanagari script-based CAPTCHA
is based on the fact that it is used by a large number of Indian languages
including Hindi which is the third most spoken language. There is potential for
an exponential rise in the applications that are likely to be developed in that
script thereby making it easy to secure Indian language based applications.Comment: 10 pages, 8 Figures, CCSEA 2011 - First International Conference,
Chennai, July 15-17, 201
A simple generic attack on text captchas
Text-based Captchas have been widely deployed across the Internet to defend against undesirable or malicious bot programs. Many attacks have been proposed; these fine prior art advanced the scientific understanding of Captcha robustness, but most of them have a limited applicability. In this paper, we report a simple, low-cost but powerful attack that effectively breaks a wide range of text Captchas with distinct design features, including those deployed by Google, Microsoft, Yahoo!, Amazon and other Internet giants. For all the schemes, our attack achieved a success rate ranging from 5% to 77%, and achieved an average speed of solving a puzzle in less than 15 seconds on a standard desktop computer (with a 3.3GHz Intel Core i3 CPU and 2 GB RAM). This is to date the simplest generic attack on text Captchas. Our attack is based on Log-Gabor filters; a famed application of Gabor filters in computer security is John Daugman’s iris recognition algorithm. Our work is the first to apply Gabor filters for breaking Captchas
CAPTCHA Types and Breaking Techniques: Design Issues, Challenges, and Future Research Directions
The proliferation of the Internet and mobile devices has resulted in
malicious bots access to genuine resources and data. Bots may instigate
phishing, unauthorized access, denial-of-service, and spoofing attacks to
mention a few. Authentication and testing mechanisms to verify the end-users
and prohibit malicious programs from infiltrating the services and data are
strong defense systems against malicious bots. Completely Automated Public
Turing test to tell Computers and Humans Apart (CAPTCHA) is an authentication
process to confirm that the user is a human hence, access is granted. This
paper provides an in-depth survey on CAPTCHAs and focuses on two main things:
(1) a detailed discussion on various CAPTCHA types along with their advantages,
disadvantages, and design recommendations, and (2) an in-depth analysis of
different CAPTCHA breaking techniques. The survey is based on over two hundred
studies on the subject matter conducted since 2003 to date. The analysis
reinforces the need to design more attack-resistant CAPTCHAs while keeping
their usability intact. The paper also highlights the design challenges and
open issues related to CAPTCHAs. Furthermore, it also provides useful
recommendations for breaking CAPTCHAs
Embedded noninteractive continuous bot detection
Multiplayer online computer games are quickly growing in popularity, with millions of players logging in every day. While most play in accordance with the rules set up by the game designers, some choose to utilize artificially intelligent assistant programs, a.k.a. bots, to gain an unfair advantage over other players. In this article we demonstrate how an embedded noninteractive test can be used to prevent automatic artificially intelligent players from illegally participating in online game-play. Our solution has numerous advantages over traditional tests, such as its nonobtrusive nature, continuous verification, and simple noninteractive and outsourcing-proof design. © 2008 ACM
A Survey on Breaking Technique of Text-Based CAPTCHA
The CAPTCHA has become an important issue in multimedia security. Aimed at a commonly used text-based CAPTCHA, this paper outlines some typical methods and summarizes the technological progress in text-based CAPTCHA breaking. First, the paper presents a comprehensive review of recent developments in the text-based CAPTCHA breaking field. Second, a framework of text-based CAPTCHA breaking technique is proposed. And the framework mainly consists of preprocessing, segmentation, combination, recognition, postprocessing, and other modules. Third, the research progress of the technique involved in each module is introduced, and some typical methods of segmentation and recognition are compared and analyzed. Lastly, the paper discusses some problems worth further research
- …