Security News > 2021 > March > Determining Key Shape from Sound

It's not yet very accurate or practical, but under ideal conditions it is possible to figure out the shape of a house key by listening to it being used.

In this paper, we propose SpiKey, a novel attack that significantly lowers the bar for an attacker as opposed to the lock-picking attack, by requiring only the use of a smartphone microphone to infer the shape of victim's key, namely bittings(or cut depths) which form the secret of a key.

When a victim inserts his/her key into the lock, the emitted sound is captured by the attacker's microphone.

SpiKey leverages the time difference between audible clicks to ultimately infer the bitting information, i.e., shape of the physical key.

As a proof-of-concept, we provide a simulation, based on real-world recordings, and demonstrate a significant reduction in search spacefrom a pool of more than 330 thousand keys to three candidate keys for the most frequent case.

For one thing, the method relies on the key being inserted at a constant speed.

News URL

https://www.schneier.com/blog/archives/2021/03/determining-key-shape-from-sound.html