text: Assistant Professor, Dept.of IT, R.V.R. & J.C. College of Engineering, Chowdavaram, Guntur, Acharya Nagarjuna University
  Evaluation of Captcha technologies towards a Graphical password scheme used for User Authentication Online guessing attacks, relay attacks and shoulder surfing attacks are handled, where Captcha as graphical passwords (CaRPS) and reCAPTCHA. Wheare CaRPS is click-based graphical passwords where a sequence of clicks on an image is used to derive a password. Dynamic captcha challenge image is used for each login attempt in CaRPS. Text Captcha and image-recognition Captcha are used in CaRPS scheme where reCAPTCHA is built for security. Armed with state of the art technology, it always stays at the forefront of spam and abuse fighting trends. reCAPTCHA is on guard for you, so you can rest easy. . Text CaRPS scheme constructs the password by clicking the right character sequence on CaRPS images. reCAPTCHA doesn't depend solely on text distortions to separate man from machines. Rather it uses advanced risk analysis techniques, considering the user's entire engagement with the CAPTCHA, and evaluates a broad range of cues that distinguish humans from bots provides an unparalleled view into abusive activity on the internet
  Venkata Srinivasu Veesam,Bandaru Satish Babu."Evaluation of Captcha Technologies towards Graphical Password Scheme". International Journal of Computer Engineering In Research Trends (IJCERT) ,ISSN:2349-7084 ,Vol.2, Issue 02,pp.98-106, February - 2015, URL :https://ijcert.org/ems/ijcert_papers/V2I22.pdf,