Captcha

IEEE TRANSACTIONS ON INFORMATION FORENSICS AND SECURITY, APRIL 2009 1 Exploiting the Human-Machine Gap in trope Recognition for Designing CAPTCHAs Ritendra Datta, Member, IEEE, Jia Li, senior Member, IEEE, and James Z. Wang, Senior Member, IEEE view Security researchers convey, for long, devised mechanisms to prevent adversaries from conducting automatize network attacks, such as denial-of-service, which lead to signi? gouget wastage of resources. On the other hand, several(prenominal) attempts have been made to automatically recognize generic return tos, make them semantically searchable by kernel, annotate them, and associate them with linguistic indexes. In the curriculum of these attempts, the limitations of state-of-the-art algorithms in mimicking charitable hallucination have conk out exposed. In this paper, we explore the maturation of this limitation for potentially preventing automated network attacks. While artless natural mental images have been s hown to be algorithmically recognizable and searchable by content to moderate levels, controlled distortions of speci?c character and strength can potentially make machine experience harder without affecting human recognition.

This disparity in recognizability makes it a shiny candidate for automated Turing tests called CAPTCHAs which can differentiate humans from machines. We through empirical observation cultivation the application of controlled distortions of varying nature and strength, and their effect on human and machine recognizability. While human recognizability is measured on the undercoat of an extensive user study, machine recognizability is based on ! memory-based contentbased image retrieval (CBIR) and matching algorithms. We give a circumstantial exposition of our experimental image CAPTCHA system, IMAGINATION, that uses systematic distortions at its core. A signi? bevel square research topic within signal analysis, CBIR is really conceived present as a tool for an adversary, so as to answer us design more foolproof image CAPTCHAs. mightiness Terms Automated Turing...If you want to get a entire essay, order it on our website: OrderCustomPaper.com

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