1. A method of authentication for an electronic device, the method comprising: capturing a plurality of biometric images in succession over a period of time with one or more sensors configured to capture the plurality of biometric images while a user is interacting with a user interface of the electronic device to input user data for a non-authentication operation; for each image of the plurality of biometric images: determining a key of the user interface associated with the capture of the image; and comparing the image with at least one reference image, based on the associated key; and providing information indicative of a result of the comparisons.