Embodiments described herein may help to provide a lock-screen for a computing device. An example method involves: (a) while a computing device is locked, displaying an interface that comprises a fixed arrangement of input regions, wherein an image from a set of images is displayed in each input region, and wherein each input region is associated with an image-name for the image that is displayed in the input region, (b) receiving audio data that comprises speech, (c) detecting a sequence of one or more of the image-names in the speech, (d) determining an input sequence based on the input regions that are associated with the detected sequence of image-names, (e) determining whether or not the input sequence matches a predetermined unlock sequence, and (f) if the input sequence matches the predetermined unlock sequence, then unlocking the computing device.