Date Added: Jan 2010
With the aim of introducing new schemes with graphical passwords, this paper proposes CAPTCHA that is a text-based scheme. Text-based password schemes are provided with in-built security and usability problems that lead to the growth of graphical password schemes. Most of these schemes are exposed to spyware attacks. Completely Automated Public Turing tests to tell Computers and Humans Apart (CAPTCH) is a program that generates and grade tests that can be solved by humans but away from the capabilities of current computer programs to harvest passwords. It is a graphical password scheme discussed in this document that is designed to raise the cost of adversaries by order of magnitude. A spyware is software that gathers information from a computer's use and sends it to the third party. It is one of the most common security threats to a computer system. CAPTCHA mentioned in the document is designed to resist automatic adversarial attacks and has a range of applications for practical security, including online polls, free email services, search engine bots, worms and spam, and preventing dictionary attacks. This paper is divided into various sections and provides reliable data and figures. CAPTCH discussed in this report can protect user's password against spyware attacks. This solution can enhanced current security and increased the effectiveness for computer security. However, the results of this document indicate the improvement of usability in the future work.