Captcha Recognition and Robustness Measurement using Hybrid Approaches

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 methods are striving to turn out to be difficult for bots, they are gradually becoming difficult and annoying for human users as well. This paper carries out a systematic study of various Text-based Captchas and proposes the application of Forepart based prediction and Rowwise mapping to break these captchas to evaluate their robustness. Captcha segmentation and recognition is based on Forepart prediction, necessity sufficiency matching and masking. Keywords—CAPTCHA, Forepart Technique, Vertical Line, Row-wise map99ping, Recursive Function, Robustness.