Protection through multimedia CAPTCHAS

CAPTCHAS which are well known as complete automatic public Turing test to tell computers and humans apart are a modern implementation of the Turing test, which ask a series of questions of two players: a human and computer. But both of the players pretend to be human. On the bases of the answers the judge has to decide which one is human and which one is computer, but the judge itself is a computer. In this article, we review current CAPTCHAs. After analysis of all the current CAPTCHAS we propose a new 3-D AI CATCHA which has all the strengths of existing CAPTCHAS to provide a better security alternative for ecommerce.