According to the invention a system for authenticating a user of a device is disclosed. The system may include a first image sensor, a determination unit, and an authentication unit. The first image sensor may be for capturing at least one image of at least part of a user. The determination unit may be for determining information relating to the user's eye based at least in part on at least one image captured by the first image sensor. The authentication unit may be for authenticating the user using the information relating to the user's eye.