1. A method comprising: creating, by a processor of a computing device, an enrollment template for a user, the enrollment template being derived from one or more enrollment images of the user's face and being usable by a face-based authentication system to authenticate the user's identity; determining, by the processor, a first set of metadata associated with the one or more enrollment images, the first set of metadata pertaining to environmental or situational conditions at the time of creating the enrollment template; storing, by the processor, the first set of metadata with the enrollment template; capturing, by the processor at a time of user authentication, an input image of the user's face; determining, by the processor, a second set of metadata associated with the input image, the second set of metadata pertaining to environmental or situational conditions at the time of capturing the input image; calculating, by the computing device, a computational distance between features extracted from the input image and the enrollment template, wherein the computational distance is increased if a degree of difference between the first set of metadata and the second set of metadata is relatively large, and wherein the computational distance is decreased if the degree of difference between the first set of metadata and the second set of metadata is relatively small; and determining, by the computing device, whether to authenticate the user based on the computational distance.