Drawing CAPTCHA
Nowadays, many daily human activities such as education, commerce, talks, etc. are carried out through the Internet. In cases such as the registering in Web sites, some hackers write programs to make automatic false enrolments which waste the resources of the Web site while this may even stop the entire Web site from working. Therefore, it is necessary to tell apart human users from computer programs which is known as CAPTCHA (completely automated public Turing test to tell computers and human apart). CAPTCHA methods are mainly based on the weak points of OCR (optical character recognition) systems while using them are undesirable to human users and esp. difficult in tools such as PDA's or mobile phones that lack a big keyboard. On the other hand, the use of Internet services has also expanded on such devices. This paper has attempted to provide a method to tell apart human users from computer programs by drawing lines with the PDA light pens. In this method, numerous dots are drawn on a screen with noisy background, some of which are diverse from the others, which the user has to connect them to each other. Considering the weakness of computers in identifying these dots, the human user can be recognized from the computer program. The proposed method was implemented by the Java programming language