A Novel Architecture for the Generation of Picture Based CAPTCHA

摘要

Denial of service attacks at application layer is major threat today. Web Programmers have come out with CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart) mechanism to mitigate the impact of DoS attacks. Most of the CAPTCHA today are OCR based which is having two fold limitations. Firstly several automated tools that are capable of reading the CAPTCHA have emerged. Secondly the CAPTCHA is not comfortable for the human to read and feed the correct information online to send their web request. In order to overcome these difficulties a new type of CAPTCHA is introduced namely picture based CAPTCHA. It helps the user to overcome the drawbacks of the previous approach since it's easy to use and understand and is also more secure than text based CAPTCHA. In this paper we propose a redesigned layout (model) for picture based CAPTCHA, which will provide an upper hand than the existing techniques. Our security analysis shows that the proposed model yields better results than other picture based CAPTCHA.