A Completely Automated Public Turing Test to Tell Computers and Humans Apart (CAPTCHA) is a simple test that used on websites differentiate between human users automated attacks indulge in spamming other fraudulent activities. text-based CAPTCHA the most popular security technique by many Internet, such as Microsoft, Google eBay, secure their sites from attacks. By design, however, unable legit...

22 COPublished by the ieee COmPuter and reliability sOCieties ■ 1540-7993/09/$26.00 © 2009 ieee ■ July/august 2009 Completely Automated Public Turing Tests to Tell Computers and Humans Apart (CAPTCHAs) are now an almost standard security mechanisms for defending against undesirable and malicious bot programs on the Internet (especially those bots that can sign up for thousands of accounts a min...

The advent of electronic voting gives rise to a new threat: Adversaries may execute undetectable, automated attacks against the system. Elections are often secured through complex policies, which may be difficult to enforce; Completely Automated Public Turing Tests to Tell Computers and Humans Apart (CAPTCHAs) provide an inexpensive alternative. The goal of this study is to introduce a unique a...

In this paper, we develop some new Captchas belonging to genre — “CAPTCHAs with a purpose.” These CAPTCHAs apart from having its applications serve some useful purpose. reCAPTCHA is one such Captcha developed at Carnegie Mellon University. It helps to digitize books. Another such Captcha is Asirra developed at Microsoft which provides homes for homeless animals. In this paper, we present Time b...

A CAPTCHA is a challenge-response test often used on the Web to determine whether a Web site’s visitor is a human or an automated program (so called bot). Existing and widely used CAPTCHA schemes are based on visual puzzles that are hard to solve on mobile devices with a limited screen. We propose to leverage movement data from hardware sensors to build a CAPTCHA scheme suitable for mobile devi...

A CAPTCHA is a program that allows or denies access to services by generating and grading test that humans can pass but current computer programs cannot. Captchas are generally used to protect free web services from automated programs. Also, they can provide an idea of which fields in artificial intelligence are the most explored and which could be researched in the near future. Most of the tes...

A clickable, affinity-based probe (AfBP), which was modified from staurosporine (a natural product kinase inhibitor), has been synthesized and used in situ for activity-based proteome profiling of potential cellular targets of staurosporine in HepG2 cancer cells.