Handwritten CAPTCHA: using the difference in the abilities of humans and machines in reading handwritten words

Handwritten text offers challenges that are rarely encountered in machine-printed text. In addition, most problems faced in reading machine-printed text (e.g., character recognition, word segmentation, letter segmentation, etc.) are more severe, in handwritten text. In this paper we present the application of human interactive proofs (HIP), which is a relatively new research area with the primary focus of defending online services against abusive attacks. It uses a set of security protocols based on automatic tests that humans can pass but the state-of-the-art computer programs cannot. This is accomplished by exploiting the differential in the proficiency between humans and computers in reading handwritten word images.