Multilingual CAPTCHA
Currently, many daily human activities such as education, commerce and talks are carried out through the Internet. In cases such as the registering in websites, some hackers write programs to make automatic false involvements which waste the resources of the website while this may even stop the entire website 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. In this paper a method has been presented for telling the human users and computer programs apart on the basis of choice of an object shown on the screen. The user interface of this method is multilingual. At the beginning of the test, the user chooses his/her native language. After that, all of the messages are shown in the selected language. The messages are translated using an online translator. While most of the available CAPTCHA methods assume that user knows English language, in this method, the user doesn't need to be familiar with English language. In this method some objects are chosen randomly and the pictures about these topics are searched and downloaded from the Internet. Then all of the pictures are shown on the screen. After that, the user is asked to choose a specific object. The main advantage of this method is that non-English users can use it easily, even if they don't know English language. This method has been implemented by the PHP language.