Researchers Can Duplicate Keys From the Sounds They Make In Locks

Researchers have demonstrated that they can make a working 3D-printed copy of a key just by listening to how the key sounds when inserted into a lock. Slashdot reader colinwb writes: While you cannot hear the shape of a drum it seems you can hear the shape of one type of key from the sound it makes in the lock. That says it all really, but [here's how Soundarya Ramesh and her team at the National University of Singapore accomplished this feat]: "[The NUS team developed and tested what it calls SpiKey, an end-to-end attack technique for, as its name suggests, spying on Yale/Schlage type keys and using signal processing software to infer their correct shapes.] Once they have a key-insertion audio file, SpiKey's inference software gets to work filtering the signal to reveal the strong, metallic clicks as key ridges hit the lock's pins [and you can hear those filtered clicks online here]. These clicks are vital to the inference analysis: the time between them allows the SpiKey software to compute the key's inter-ridge distances and what locksmiths call the 'bitting depth' of those ridges: basically, how deeply they cut into the key shaft, or where they plateau out. If a key is inserted at a nonconstant speed, the analysis can be ruined, but the software can compensate for small speed variations.

The result of all this is that SpiKey software outputs the three most likely key designs that will fit the lock used in the audio file, reducing the potential search space from 330,000 keys to just three. 'Given that the profile of the key is publicly available for commonly used [pin-tumbler lock] keys, we can 3D-print the keys for the inferred bitting codes, one of which will unlock the door,' says Ramesh." The article has a link to a 15-minute video presentation of the research and to another article on the research.

Read more of this story at Slashdot.