These computing devices typically include sensors that can be used to uniquely identify the user, or verify that an action is legitimately performed by the user. For example, mobile devices, such as smartphone 104, wearable device 108, a tablet computer or other personal electronic device, include sensors such as: a touchscreen; an accelerometer; a gyroscope; an inertial sensor; a virtual keyboard-timing sensor; an ambient light sensor; a camera; an odor sensor; a temperature sensor; a barometric-pressure sensor; a cellular radio signal strength sensor; a Bluetooth radio signal strength sensor; a near-field communication (NFC) sensor; an infrared sensor; a battery sensor; a force-touch measurement sensor; a multi-touch measurement sensor; and a microphone. (Note that instead of using a microphone to collect sound and voice, sound and voice can alternatively be captured using motion sensors, such as an accelerometer or a gyroscope.) Laptop computer 106 or a desktop computer may include sensors, such as: a keyboard-timing sensor; a mouse sensor; a trackpad sensor; a Bluetooth radio signal strength sensor; an image sensor or camera; a network proximity sensor; an infrared sensor; and a battery sensor.

Computing environment 100 can include other devices with sensors, which are located in, on or near a person's body, including: medical indigestibles, subdermal implants, electronic tattoos, smart clothing or accessories, and physical authentication devices.

In addition, computing environment 100 can include other devices in the vicinity of user 102 having sensors and network connectivity, such as: a camera 103, a Wi-Fi? access point 110, a Bluetooth? beacon 112, a home thermostat, automobile components, security systems, televisions and other entertainment devices, and IoT (Internet of Things) devices.