Comment by mxwsn
2 years ago
The example figure shows a key hit every half second, which suggests a pecking style of typing at around 24 wpm. This way the model gets very clean waveforms. I wonder how their approach would work with average or fast typists. The sound profiles might be much harder to link to characters.
Even if there was ambiguity, some data is better than none. Given enough training data, I suspect you could find repeatable patterns in standard typists: on a qwerty layout, after typing an "A", "Q" takes 1.2-2.3x as long to type as a "J" kind of pairwise tempo patterns. Anything to reduce the search space from brute-forcing every candidate character.
Even better if the target uses a passphrase, "hXXXse battXXX stXXXXX cXXXXXX" becomes interpretable given a few landmark letter identified with high probability.
Sovjet listened successfully to typewrites back in the 1970s.
Impressive. To be fair, a lot of typewriters jam if you press more than one key at a time, plus they are very loud.
What's more impressive that the vibration of the glass windows can be used, too.