Answer: Tracking taps and swipes.
You might want to think twice the next time you decide to swipe right.
CNET reports that researchers from Australia’s Commonwealth Scientific and Industrial Research Organisation have confirmed it is possible that “touch gestures contain sufficient information to uniquely identify and track users.” The team presented a paper detailing their research at the Privacy Enhancing Technologies Symposium in Barcelona last week.
They collected data using an Android app built to track swipes, taps and pinches on a touchscreen. They learned that 73.7 percent of information on a user can be gleaned from writing samples, while 68.8 percent can be determined from left swipes. When this data was combined, writing samples and taps and swipes on a screen, the researchers could uncover 98.5 percent of information about a user.
The research paper can be viewed here.