Reza Shali - Faculty of Computer and Information Technology Engineering, Qazvin Branch, Inslamic Azad University, Qazvin, Iran

Abstract We present IMPTCHA, a new CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) as a security measure to recognize human users. The proposed system uses images instead of distorted text to label images as a valuable output. IMPTCHA is generated from images on the Web. For passing this CAPTCHA, users must type two words for description of two images. When users pass the challenge, the provided meaningful labels are used to determine the content of images. In addition, semantic graphs for labels and images are created and according of it we’ll able to develop an image semantic search engine. Due to usage of images in this system, and its architecture, it is highly secure compared to its counterparts. In a user study involving ۶۰ participants, IMPTCHA’s word accuracy is measured to be ۹۸.۱۸% while ۶۱.۲۶% of users could pass the challenge. Keywords:CAPTCHA, Ontology, Image labeling, Security

CAPTCHA, Ontology, Image labeling, Security