Abstract: An authentication process may involve presenting an image on a display device, such as an icon associated with an application, indicating an area for a user to touch. At least partial fingerprint data may be obtained during one or more finger taps or touches in the area. Based on a comparison of the partial fingerprint data and master fingerprint data of the rightful user, a control system may determine whether to invoke a function. Invoking the function may involve authorizing a commercial transaction or unlocking the display device. In some implementations, determining whether to invoke the function may be based on a level of security.