CAPTCHA stands for Completely Automated Public Turing Tests to Tell Computers and Humans Apart .A CAPTCHA is a program that protects websites against bots –automated scripts by generating and grading tests that humans can pass but current computer programs cannot. The aim is to allow the server to identify the visitor is a human or a computer, and only provide services to human. It can improve the current server system and user information security.The increase in bots breaking CAPTCHAs shows the ineffectiveness of the text-based CAPTCHAs that are used on most websites and Webmail services today. Bots can easily read the distorted letters and words using optical character recognition (OCR) or break the CAPTCHA using a dictionary attack. The weakness of each CAPTCHA scheme is summarized and accordingly we make an approach to build our CAPTCHA scheme. Considering the case study results and including other points which may pose difficulty for the OCR systems. In this paper we proposed a new technique to build a CAPTCHA which is hybrid (both Picture and Text based with multiple fonts). An image is being rendered on the screen and many text labels of multiple fonts drawn over it. A user has to identify the correct name of the underlying image among the set of text labels that are scattered over it, in order to pass a human verification test. We proposed to use multiple fonts for each letter of a single word inside a Captcha which increases the more complexity of training OCR software.
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