Patent attributes
Methods, systems, and apparatus, including computer programs encoded on computer storage media, for authenticating users based on a sequence of biometric authentication challenges. In one aspect, a process includes receiving a first image of the face of the user and processing the first image according to a first authentication process to determine whether the face of the user shown in the first image matches the face of an authorized user. A second authentication process including a sequence of biometric authentication challenges is identified. The sequence includes at least one facial expression challenge. The user is authenticated in response to determining that the first authentication process is satisfied based on the face of the user shown in the first image matching the face of the authorized user and the second authentication process is satisfied based on the user providing a valid biometric response to each biometric authentication challenge.
