A CAPTCHA is a Turing test to distinguish human users from automated scripts to defend against internet adversarial attacks. As text-based CAPTCHAs (TBC) have become increasingly difficult to solve, image-based CAPTCHAs, and particularly face recognition CAPTCHAs (FRC), offer a chance to overcome TBC limitations. In this paper, we systematically design and implement a practical FRC, informed by psychological findings. We use gray-scale and binary images, which are computationally inexpensive to generate and deploy. Furthermore, our FRC complies with CAPTCHA design guidelines, thereby ensuring its robustness.
['Terence Sim', 'Hossein Nejati', 'James Chua']
Face recognition CAPTCHA made difficult