Technology Summary

A system for the generation of attack-resistant, user-friendly, image-based CAPTCHAs. Controlled distortions are produced on randomly chosen images and present them to the user in the form of a mosaic. The images are distorted in a way that precludes the use of state-of-the-art computer image recognition technologies. In a preferred implementation of our technology, we use a two step verification process. In the first step, the user clicks near the center of any picture in the mosaic. In the second step, the user is asked to identify a distorted image by selection from a list. This two-round click-and-annotate process makes the CAPTCHA user friendly and very effective.