Abstract
We present variations and modifications of the image-feature based human identification protocol proposed by Jameel et al with application to user authentication on mobile devices with limited display capabilities. The protocols introduced are essentially reduced versions of the original protocol with a minor tradeoff between security and usability. However, the proposed protocols are not aimed for computation and memory restrained devices. A brief user survey highlights the usability. By employing realistic assumptions pertaining to mobile devices, we show that the protocols are secure under the conjectured difficulty of extracting the secret feature from the observation of images and their binary answers. The adversary considered is strictly passive.