Next, as illustrated by the example in FIG. 2, the system performs the authentication process. As shown in FIG. 2, during operation of a smartphone 204, a trigger event 202 occurs, which causes an agent running on smartphone 204 to collect sensor data 206. Next, the smartphone 204 performs a feature-extraction operation 208 on the sensor data 206 to produce a feature vector 210, which is communicated to a cloud server 212. Cloud server 212 then uses a model generated through a machine-learning process to determine a security score and associated confidence value 214 for a user, wherein the security score indicates a probability that the sensor data 206 is associated with the user.

Authentication System

FIG. 3 illustrates how authentication agents 302 and 304 operate in an exemplary authentication system 300 in accordance with the disclosed embodiments. Within authentication system 300, authentication agents 302 and 304 are responsible for handling integration with authentication mechanisms on various sites and services. In some embodiments, authentication agents 302 and 304 are implemented as browser plugins that control user-authentication operations that take place in associated web browsers.