A Review of Bot Protection using CAPTCHA for Web Security

Abstract

Today several daily activities such as communication, education, E-commerce, Entertainment and tasks are carried out by using the internet. To perform such web activities users have to register regarding the websites. In registering websites, some intruders write malicious programs that waste the website resources by making automatic false enrolments that are called as bots. These false enrolments may adversely affect the working of websites. So, it becomes necessary to differentiate between human users and Web bots (or computer programs) is known as CAPTCHA. CAPTCHA is based on identifying the distorted text, the color of image, object or the background. This paper examines CAPTCHAs and its working and literature Review. This paper also provides classification of CAPTCHAs, its application areas and guidelines for generating a captcha.