Many CAPTCHA proposals have shortcomings in their design or implementation that make themmuch weaker than intended. In this paper we study Captcha2, a commercial algorithm, as a means of showing typical flaws that make many CAPTCHAs prone to successful low-cost attacks. The attack we present makes no use of any AI techniques, not affecting the resilience of the original AI problem this CAPTCHA ...

CAPTCHAs are a widely deployed mechanism to distinguish a legitimate human user from a computerized program trying to abuse online services. Attackers, however, have devised a clever and an economical way to bypass the security provided by CAPTCHAs by simply relaying CAPTCHA challenges to remote human-solvers. Most existing varieties of CAPTCHAs are completely vulnerable to such relay attacks, ...

Image tag recommendation in social media systems provides the users with personalized tag suggestions which facilitate the users’ tagging task and enable automatic organization and many image retrieval tasks. Factorization models are a widely used approach for personalized tag recommendation and achieve good results. These methods rely on the user’s tagging preferences only and ignore the conte...

This work focuses on development of an alternative aural CAPTCHA technology based on a speech transcription task. The principal goals are (1) to provide a better quality of service for visually impaired web users who currently have few alternatives for accessing web services protected by CAPTCHAs based on visual perception tasks, (2) as a side effect of CAPTCHA use, collect meaning data, such a...

Completely Automatic Public Turing test to tell Computers and Humans Apart (CAPTCHA) is a HIP (Human interactive Proof) system. CAPTCHAs are used to improve the security of Internet based applications in order to ensure that a web based application which is intended to be used by a human being is not maliciously used by Artificially Intelligent programs called bots. As the current CAPTCHA metho...

Online detection of protection orbit round as an important part of the train, the tread wear parameters traffic safety is important. Like the wheel of the measurement techniques based on optical screenshots Dimensions dynamic detection 'access to a complete round of the contour image is essential. For the round image features is proposed based on region developing the round image segmentation a...

Any Web user is a potential knowledge contributor, but it remains a challenge to make them devote their time contributing to some purpose. In order to align individual with social interests, we selected the CAPTCHA Web resource protection application to embed knowledge elicitation within the users' main task of accessing a Web resource. Consequently, unlike previous knowledge acquisition approa...

Cloud computing is simply a metaphor for the internet. User does not required knowledge, control, and ownership in the computer infrastructure. User simply access or rent the software and paying only for what they use. Advantage of cloud computing is huge like Broad network access, Cost effectiveness, Rapid elasticity, Measured services, On-Demand service, Resource pooling, Location independenc...

Automatic image annotation is a difficult and highly relevant machine learning task. Recent advances have significantly improved the state-of-the-art in retrieval accuracy with algorithms based on nearest neighbor classification in carefully learned metric spaces. But this comes at a price of increased computational complexity during training and testing. We propose FastTag, a novel algorithm t...

Automatic Image Tagging seeks to assign relevant words (e.g. “jungle”, “boat”, “trees”) to images that describe the actual content found in the images without intermediate manual labelling. Current approaches are largely based on categorization, and treat the tags independently, so an annotation (jungle,trees) is just as plausible as (jungle,snow). The goal of this dissertation was to develop a...