CAPTCHAs based on the Principle- Hard to Separate Text from Background
نویسندگان
چکیده
CAPTCHAs have become a very popular security mechanism used to prevent automated abuse of online services intended for humans. Different flavors of CAPTCHA can be seen on Internet. However, a wide variety of CAPTCHAs have been successfully attacked by automated programs. This has made CAPTCHA design an interesting area for research. Among various flavors of CAPTCHA text based are most preferable because of its low implementation cost but this category of CAPTCHA can be attacked with very high success rate. To provide stronger and user-friendly text based CAPTCHA, in this paper, we propose three text based CAPTCHA designsBarCAPTCHA, TransparentCAPTCHA and ThreadCAPTCHA based on the design principle “hard to separate text from background”. The underlying security assumption is that if an automated program cannot locate text in CAPTCHA then it cannot do further processing to identify the characters of it. Keywords— CAPTCHA, security, automated abuse, online service, text based, design principle.
منابع مشابه
Mitigating Dictionary Attacks with Text-Graphics Character Captchas
We propose a new construct, the Text-Graphics Character (TGC) CAPTCHA, for preventing dictionary attacks against password authentication systems allowing remote access via dumb terminals. Password authentication is commonly used for computer access control. But password authentication systems are prone to dictionary attacks, in which attackers repeatedly attempt to gain access using the entries...
متن کاملUsability Investigation on the Localization of Text CAPTCHAs: Take Chinese Characters as a Case Study
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...
متن کاملA Benchmark for Designing Usable and Secure Text-based Captchas
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 ...
متن کاملOn the security of text-based 3D CAPTCHAs
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...
متن کاملProtection through Intelligent and Multimedia Captchas
The Complete Automatic Public Turing test to tell Computers and Humans Apart (CAPTCHA) is a modern implementation of the Turing test. A CAPTCHA asks a series of questions which are supposed to be relatively easy for mature human beings but hard for machines to answer. A CAPTCHA, as its name suggests, is generally used as a tool to distinguish human beings from machines when the corresponding pa...
متن کامل