Simple visual CAPTCHA approach

摘要

The internet has become a place where various on-line activities of different natures are carried out. Most activities require strict security measures to ensure the integrity of on-line systems such as e-commerce and business related websites. Furthermore, the proper functioning of a website is an integral part of its success. Thus, the risk of spammers and abusers is a critical one and needs to be dealt with vigilantly. Spammers often use software robots to compromise the security and the functionality of a website. Without enough security measures, spammmers can design software robots (bots) to create a huge number of fake online accounts, manipulate search engine ranking, share in on-line surveys, send out spam emails and messages or simply waste the resources of the server. One main solution for this issue is the use of a CAPTCHA system that can be used to identify if a user is a human or a software robot. In this paper we introduce a visual CAPTCHA technique that is based on generating random images by the computer, the user is then asked to click on the images that match a given pattern. The main advantage of our approach compared to other visual CAPTCHA techniques is that our system is simple and easy for by human users while extremely difficult for by software robots (bots). In addition our system does not require any database of images as the set of displayed images are randomly generated by the computer.