According to researchers from Dallas-based Southern Methodist University (SMU), it’s possible to access your information in a subtler way: by using a nearby smartphone to intercept the sound of your typing.
The team from from SMU’s Darwin Deason Institute for Cybersecurity found that acoustic signals, or sound waves, produced when we type on a computer keyboard can successfully be picked up by a smartphone.
The sounds intercepted by the phone can then be processed, allowing a skilled hacker to decipher which keys were struck and what they were typing.
The researchers were able to decode much of what was being typed using common keyboards and smartphones – even in a noisy conference room filled with the sounds of other people typing and having conversations.
“We were able to pick up what people are typing at a 41 per cent word accuracy rate. And we can extend that out – above 41 per cent – if we look at, say, the top 10 words of what we think it might be,” said Eric C. Larson, assistant professor in SMU Lyle School’s Department of Computer Science.
It might take only a couple of seconds to obtain information on what you’re typing, noted lead author Mitch Thornton, professor of electrical and computer engineering, in a paper published in the journal Interactive, Mobile, Wearable and Ubiquitous Technologies.
“Based on what we found, I think smartphone makers are going to have to go back to the drawing board and make sure they are enhancing the privacy with which people have access to these sensors in a smartphone,” Larson noted.
There are many kinds of sensors in smartphones that cause the phone to know its orientation and to detect when it is sitting still on a table or being carried in someone’s pocket.
“Some sensors require the user to give permission to turn them on, but many of them are always turned on,” Thornton explained.
“We used sensors that are always turned on, so all we had to do was develop a new app that processed the sensor output to predict the key that was pressed by a typist.”
There are some caveats, though.
“An attacker would need to know the material type of the table,” Larson said, because different tables create different sound waves when you type. For instance, a wooden table like the kind used in this study sounds different than someone typing on a metal tabletop.