CAPTCHA for Blind People

Nowadays the Internet users are from different ages and groups. The disabled people also use the Internet. Some websites are especially created for disabled people. Many Internet sites offers services for human users, but unfortunately some computer programs are designed which abuse these services. As a result some systems named CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart) have been introduced to tell apart human users and computer software. In this paper, a new CAPTCHA method is introduced which can be used by blind people. In this method a simple mathematical problem is created according to predefined patterns and converted to speech using a Text-To-Speech (TTS) system. Then the sound is played for the user and he/she must enter the answer of the question. Because answering this problem requires recognizing the speech, understanding the problem, and solving the problem, only a human user can answer this question and present computer programs are unable to solve it. In addition, answering the question is easy for blind people, because the question is consists a number of natural language sentences and the answer is a number, which can be entered easily.