Advanced Nastaliq CAPTCHA

Many websites on the Internet offer services to people. They usually ask the users to fill the registration forms for using their services. Unfortunately, some vandalistic persons write programs which make automatic fake registration. For solving this problem, CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart) systems are invented. These systems distinguish human users from computer programs. One of the CAPTCHA methods which is designed for Persian and Arabic users is Nastaliq CAPTCHA. In this method, the image of a Persian or Arabic word which is written in Nastaliq font is chosen from a dictionary, and it is shown to the users, then they are asked to type it. However, this method requires a large space for keeping the images and the library should also be very extensive, which requires large expenses to create. Also because this method uses its word from a dictionary, it can be broken in by using a dictionary. In this paper a solution for solving this problem is proposed. In our method, instead of using a large database of prepared word images written in Nastaliq font, each time a random meaningless Persian/Arabic word is generated and shown to the user. Therefore, we do not need to make a local database for images, so the costs are reduced. Also because this method does not use a dictionary, the possibility of breaking the method is reduced.