Secure phone uses sonar to watch your mouth saying a passphrase

Bouncing sound waves off your lips, jaw and tongue as you speak a passphrase can make sure the person trying to access your secure information is really you

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“My voice is my password.” Passphrases that use biometric voice recognition to verify it’s really you are becoming increasingly popular. But their increasing use carries a risk: someone with a recording of your voice could easily splice the right spoken words together and spoof their way into your digital life. Now a new technology detects such shenanigans – using sonar.

Even as biometrics are replacing passwords, voice recognition is becoming more vulnerable to spoofing. Fuelling this risk, says security engineer Jie Yang at the State University of Florida in Tallahassee, is the way people now post so much audio and video on social media. “This makes it relatively easy to obtain voice samples from a target,” he says.

So Yang and his colleagues devised a technology that detects and defeats such misuse of recordings. VoiceGesture is able to not only recognise that a passphrase