These days many people go through their daily activities interacting with a myriad of devices they own, for example, smart-phones, tablet PCs, net-books, laptops, desktop computers, smart televisions (TVs), car onboard systems, photo cameras, infotainment systems, etc. These devices are also called “companion devices” of a person because they are closely associated with the person. Many of these devices are mobile devices and travel with their owners moving around different types of contexts, some private contexts and some public contexts. Examples of private contexts are home, car, office, etc. Examples of public contexts are bar, gym, airport, etc.
Handling multiple devices, especially in public places, gives rise to high risk of losing one of the devices-a device may be stolen or the owner may forget one of the multiple devices at a certain place. For example, a common scene in a bar is people working on their laptops while their smart-phones are on the table. In such a scenario, people may walk away from the bar leaving their smart-phone on the table. Likewise, during business travel a person waiting for a flight may try to catch up work and leave behind their laptop in a hurry to find the best seat in the plane. Another example is that during a security check at the airport a person may leave behind their laptop or smart-phone near the X-ray machines trying to run to catch their flight.
One way to protect the data on these devices left behind is to regularly backup data or to synchronize data with previous data versions. However, such methods do not preclude the device from being stolen or lost. Neither do these methods avoid possible access to the data on these devices and usage of the devices.