Turing test to tell Computer and Humans Apart. CAPTCHAs

2011

A "Completely Automated Public Turing test to tell Computers and Humans Apart" (CAPTCHA) is a mechanism widely used nowadays for protection of web applications, interfaces, and services from malicious users. A questionnaire-based survey combined with a real usage scenario of a native-language CAPTCHA mechanism was conducted in order to investigate several aspects that affect end-user perceptions related to the quality of CAPTCHA. A total of 210 participants of age between 19 and 64 participated during May and July 2010. The survey results validate the common belief that CAPTCHAs are still difficult for humans to solve. They also provide insights that can be applied to improve users" experience on interacting with CAPTCHA systems.

IOP Conference Series: Materials Science and Engineering

The notion of CAPTCHAs has been around for more than two decades. Since its introduction, CAPTCHAs have now become a ubiquitous part of the Internet. Over the years, research on various aspects of CAPTCHAs has evolved and different design principles have emerged. This article discusses text-based CAPTCHAs in terms of their fundamental requirements, namely, security and usability. Practicality necessitates that humans must be able to correctly solve CAPTCHA challenges, while at the same time automated computer programs should have difficulty solving the challenges. This article also presents alternative paradigms to text-based CAPTCHA design that have been examined in previous work. With the advances in techniques to defeat CAPTCHAs, the future of automated Turing tests is an open question.

— CAPTCHAs are short for Completely Automated Public Turing test to tell Computer and Humans Apart. The purpose of a CAPTCHA is to block form submissions from spam bots – automated scripts that harvest email addresses from publicly available web forms. The term "CAPTCHA" was coined in 2000 by Luis Von Ahn, Manuel Blum, Nicholas J. Hopper (all of Carnegie Mellon University, and John Langford (then of IBM). CAPTCHAs are used because of the fact that it is difficult for the computers to extract the text from such a distorted image, whereas it is relatively easy for a human to understand the text hidden behind the distortions. Therefore, the correct response to a CAPTCHA challenge is assumed to come from a human and the user is permitted into the website. The CAPTCHA test helps identify which users are real human beings and which ones are computer programs.

International Journal of Computer Applications, 2015

CAPTCHA (Completely Automated Public Turing Test to Tell Computer and Humans Apart) has become a ubiquitous guard utilized to prevent exploitation in web services like account registration. They are universally secure measure to distinguish real users from automated programs by using computer-generated tests that should be easy for users to solve but should be hard for malicious program. However, implementing CAPTCHAs is becoming increasingly hard due to advances in machine learning system. Furthermore, all current audio-based CAPTCHAs have been broken by automated programs and research shows that the existing implementations are very difficult and time consuming. In addition to this, more than 50 percent of people are unable to bypass the current audio-based CAPTCHAs owing to the intrinsic hardness of interpreting the noisy sound message. Consequently, the implementation of a novel voice CAPTCHA is demanded. In this paper, a technique for telling the human beings and computer programs apart based on submitting the right colour name of the object announced by the speaker has been introduced. In this technique, an object is selected from database at random, and then the selected object will be pronounced from the audio message. After that the CAPTCHA request users to submit the colour name of that object. If the colour name is submitted accurately, the system is able to decide that the client is a human and not an automated program. The main advantage of the proposed CAPTCHA is that users don"t have to memorise a group of random digits and words, which stretches the limits of individuals" short-term mind. Finally, the usability test is conducted with some individuals. In addition, discussion, limitations, and suggestions for further study are illustrated.

The science of making computers humanly to an extent in which it is capable of decision making on its own, visual cognizance, speech recognition, etc. is artificial intelligence. In a very less time span, this field has impacted several sectors of life such as medical, engineering, business, forecasting, etc. "Completely Automated Public Turing Test to Tell Computers and Humans Apart" acronyms to CAPTCHA is a test to differentiate humans from normal robots. A robot is not capable of cracking a CAPTCHA. In this paper we are focusing on how an artificial intelligence robot can solve a CAPTCHA. It is not a big deal to crack a CAPTCHA but it is a small step to a big thing i.e. consciousness in A

2006

Abstract. Completely Automated Public Turing Test to tell Computers and Humans Apart (CAPTCHA) is a –rather – simple test that can be easily answered by a human but extremely difficult to be answered by computers. CAPTCHAs have been widely used for practical security reasons, like preventing automated registration in Web-based services. However, all deployed CAPTCHAs are based on the static identification of an object or text. All CAPTCHAs, from simple ones, like typing the distorted text, to advanced ones, like recognizing an object in an image, are vulnerable to the Laundry attack. An attacker may post the test to a malicious site and attract its visitors to solve the puzzle for her. This paper focuses on sealing CAPTCHAs against such attacks by adding a dimension not used so far: animation. Animated CAPTCHAs do not have a static answer, thus even when they are exposed to laundering, unsuspected visitors will provide answers that will be useless on the attacker’s side.

IT Professional, 2005

Captcha-a completely automatic public Turing test to tell computers and humans apart-is a test that humans can pass but computer programs cannot; such tests are becoming key to defending ecommerce systems.Without them, spammers can, for example, write simple automated scripts to create hundreds of free e-mail accounts with a single command. The e-mail service provider can choose not to validate the information supplied by uses, but ends up with thousands of useless accounts. On the other hand, the provider can assume the extra burden of validating this information, but risks crippling its systems with the extra burden that validation requires. By inserting a Captcha into the login and user creation process, system administrators can defeat these automated scripts and have some assurance that an actual human is associated with the account. Similarly, Captchas are also useful in defending online shopping or auction sites by preventing spammers from posting irrelevant or bogus bids to prevent other buyers from purchasing products. Captchas are a modern implementation of the Turing test, which asks a series of questions of two players: a computer and a human. Both players pretend to be human and try to mislead the judge. Based on the answers given, the judge has to decide which one is human and which is a computer. Captchas are similar to the Turing test in that they distinguish computers from humans, except that, with a Captcha, the judge is also a computer. Captchas also differ from the Turing test because they work on a variety of sensory inputs, whereas the Turing test is conversational. Captchas come in several different types. Most generally, the Captcha is simply an image composed of pseudorandom letters and numbers placed either in front of an obfuscating background or run through some degradation algorithm to make optical character recognition (OCR) of the final image impractical. HISTORY AltaVista was the first to use a simple Captcha that generated images of random text. It used the Captcha to prevent users from abusing its free-URL submission utility.Andrei Broder,AltaVista chief scientist, and his colleagues patented the technology in 2001. The AltaVista Captcha reduced abuse by 95 percent (http://msdn. microsoft.com/library/default.asp?url=/library/ en-us/dnaspp/html/hip_aspnet.asp). In 2000, Udi Mamber of Yahoo was looking for ways to prevent bots from joining the online chat rooms to post advertisements. Researchers at Carnegie Mellon University took up the problem and proceeded to quantify desirable characteristics of Captchas as well as generate several types, including the Gimpy type described later. The Xerox Palo Alto Research Center (PARC) also actively continues to study Captchas. PARC researchers have most recently developed Baffle Captchas can provide an easily programmable way to tell computers from humans and keep spammers and bots away from e-commerce systems.

Research in Computing Science

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 tests that are based on text recognition have been broken by optical character recognition (OCR) techniques while those based on images are vulnerable to machine learning attacks. Humans make use of cognitive abilities to carry out tasks in daily life, even if they are not conscious which ones or how they use them. The current state of technology is still not enough to reproduce some human cognitive abilities, and the identification of those abilities is the basis for the design of new CAPTCHA models. In this paper we introduce seven new models of CAPTCHA to test some cognitive abilities that are supposed to be beyond the capabilities of artificial agents. We use some APIs to proof that images used in the proposals are extremely difficult to be recognized by artificial agents.

International Journal of Adaptive, Resilient and Autonomic Systems, 2012

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 party is invisible in a remote site. There are many CAPTCHAs proposed and widely used in many Internet applications, with varied strength and performance. In this article, a review of current CAPTCHAs is presented. Analysis and comparisons are provided for various CAPTCHAs. Two types of new CAPTCHAs, intelligent and multimedia CAPTCHAs, are proposed. Our experiments have shown that the newly proposed CAPTCHAs have stronger protection than most existing CAPTCHAs and they can be applied to various web applications, such as e-commerce.

CAPTCHA makes a distinction between humans and computers by employing Turing Tests. This paper discusses about the existing CAPTCHAs. A new type of CAPTCHA design which is different from the existing CAPTCHAs is also discussed.