A computing device includes a system that authenticates a user of the computing device. A first sensor obtains a first representation of a physical characteristic of the user that is compared to a registered representation of the physical characteristic of the user. A first level of access to the computing device is enabled based on the first representation of the physical characteristic matching the second representation of the physical characteristic. A second sensor obtains a first representation of a liveness characteristic of the user that indicates that the user is alive. The first representation of the liveness characteristic is compared to a registered representation of the liveness characteristic of the user. A second level of access to the computing device is enabled based on the first representation of the liveness characteristic of the user matching the second representation of the liveness characteristic of the user.