Researchers at the National University of Singapore published a paper earlier this year detailing how, using only a smartphone microphone and a program they designed, a hacker can clone your key. What’s more, if a thief was able to install malware on your smartphone, smartwatch, or smart doorbell to record the audio from afar, they wouldn’t even need to be physically nearby to pull off the attack.

The key (ahem) to the attack, dubbed SpiKey, is the sound made by the lock pins as they move over a typical key’s ridges.

“When a victim inserts a key into the door lock, an attacker walking by records the sound with a smartphone microphone,” describes the paper written by Soundarya Ramesh, Harini Ramprasad, and Jun Han.