PASSIVE IDENTIFICATION OF A DEVICE USER

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for a biometric authentication system. In one aspect, a method includes identifying a target user in proximity to a kiosk. Data for the target user is gathered from equipment on and in proximity to the kiosk. The gathered data is processed to generate a feature vector. The feature vector includes at least motion characteristics of the target user as the target user approaches the kiosk and touch input characteristics of the target user at the kiosk. A candidate user to compare to the target user is determined. Reference data for the candidate user is retrieved. The feature vector is compared to the reference data for the candidate user to determine a likelihood that the target user is the candidate user. A kiosk application is customized for the target user based on the determined likelihood.