51����

Does your digital assistant know who it’s talking to? A wearable device prototype could let voice-controlled assistants like Apple’s Siri or Amazon’s Alexa recognise their owner so they don’t take orders from anyone else.

The , developed at the University of Michigan in Ann Arbor, uses an accelerometer hidden in a pair of glasses or earphones or worn around the neck. The accelerometer measures vibrations created as the wearer speaks. An algorithm then compares those vibrations with the audio signal received by the digital assistant. If the vibrations and the audio match, then the voice command is received as normal. If not, the assistant is blocked from responding.

Computer scientists and at the University of Michigan  tested VAuth with 18 people saying 30 different commands. It was able to match speech vibrations with audio signals 97 per cent of the time, and did not act on commands issued by someone other than the device owner. Although they tested VAuth only with Android assistant Google Now, Feng and Fawaz are confident it could work with other voice assistants if their manufacturers allowed it.

Order me this

The technology comes a little too late for some Amazon Echo owners in San Diego, California, whose attentive devices tried to order toys from Amazon after overhearing a newsreader say “Alexa ordered me a dollhouse” on air. Authenticating a user’s commands would prevent this problem and could also protect against methods of “hacking” a voice-controlled device, says Feng.

It has already been shown, for example, that .

VAuth could offer security advantages over using passcodes or fingerprints to unlock a smartphone, too. “A password or fingerprint requires that you physically walk over to the device,” says at Clemson University in South Carolina. Google’s “trusted voice” feature unlocks the phone only after matching the voice command against a biometric profile of its owner’s voice. However, there are ways around this by impersonating or playing recordings of the owner’s voice to the device.

And such unlocking methods of authentication may not last long. Five minutes after a phone has been unlocked, how does it know the user is still the owner and not someone else? VAuth’s authentication, however, is continuous – it screens every voice message.

Combining this technology with biometric voice identification, says Sorber, could be the best way to secure many wireless devices. “The more mobile and untethered our computing environment gets, the harder it is to really do a great job of securing things,” he says.

Read more: How we fell in love with our voice-activated home assistants

Journal reference: arXiv,