Highlighting CAPTCHA

There are many sites specially designed for mobile phones. In cases such as the registering in Websites, some hackers write programs to make automatic false enrollments which waste the resources of the website. Therefore, it is necessary to distinguish between human users and computer programs. These systems are 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 difficult in tools such as PDAs (Personal Digital Assistant) or mobile phones that lack a big keyboard. So the Non-OCR-Based CAPTCHA methods are proposed which are do not need to type anything. In this paper a new CAPTCHA systems for touch-screen devices such as PDAs and mobile phones has been introduced which is a combination of both above-mentioned methods. In this system a random word is generated and drawn in a random place on the screen. Then various pictorial effects are applied to it and some noises are added to screen. Now the user is asked to highlight this word by the stylus. Due to the limitations of the PDA and mobile phone, OCR programs on these devices cannot recognize the shown word and only a human user can highlight the word. The proposed method was implemented by the J2ME (Java 2 Micro Edition) language and tested on a Sony Ericsson P990i mobile phone.