Image Matching CAPTCHAs

With the proliferation of Web services, it is imperative to minimize spamming and security risks. Spammers use software to automate the process of creating fake online accounts to be used later as a source of spam and illegal activities or simply to waste the resources of the website. In order to mitigate this risk, CAPTCHA was introduced with the main purpose of identifying whether the end-user is a human or a computer (i.e computer program). The benefits of CAPTCHA are now well-established and all major websites use it for registering new users. In this paper we introduce a novel CAPTCHA tecnique that is based on matching images. To avoid maintaining a data base of images, the images are. To avoid maintaining a data base of images, the images are created by the computer with random patterns that are simple for human users to match and extremely challenging for CAPTCHA breaker software to solve.