Researchers from the National University of Singapore found a way to infer key shape based on the sound the lock makes when you insert the key.
First they capture a sound recording with a standard microphone. Then they run the audio file through software to filter out the metallic clicks. This provides a time series from which they can infer likely keys.
Soundarya Ramesh presented the work at HotMobile 2020 in the talk below:
Oh to be back in graduate school again. [via kottke]
