The Battery Status API that's supported by all major browsers has gone from a theoretical method of tracking users online to a de-facto reality, Princeton researchers have discovered.
The HTML5 Battery Status API was developed by the W3C (World Wide Web Consortium), the organization that regulates most Web standards, and was introduced in most Web browsers by the summer of 2015.
The API allows browsers to share information with online entities (websites, Web services, other APIs) about the device's battery level, the time it will take to discharge the battery, and the time it will take to recharge it.
W3C argued that this API could be useful for websites and services that wanted to automatically shift to a low-power consumption mode when the underlying device's battery was draining.
From theoretical research to a cruel reality
In 2015,
four security researchers from Belgium and France, have tried to warn the W3C and other user privacy groups that this API could, in theory, be used to track users online.
