High-Entropy Visual Identification for Touch Screen Devices
The authors exhibit a system for improving the quality of user-derived keying material on touch screen devices. They allow a device to recover previously generated, highly entropic data suitable for use as (part of) a strong secret key from a user's act of identifying to the device. The system uses visual cryptography, using no additional electronics and no memorization on the part of the user. Instead, they require the use of a transparency overlaid on the touch screen. The scheme is similar to the identification scheme of but tailored for constrained, touch screen displays.