Boffins shake up smartphone with motion-sensor as microphone University of Illinois boffins have proved that someone who steals your phone can perform hardware hacks on it. As a maker-hack, The Register can't help but admire the work done to create the “VibraPhone” (even the pun is better than average). As a security vulnerability, we'll file this under “if you lose your phone, you're …
Clever boffins. I imagine someone in one of the phone companies (or all of them!) is now going off to see if a) they can turn a regular mic into a vibration sensor or b) a vibration sensor into a mic. One less component in your phone is almost always a good thing (less failure, cost, weight, etc.)
Here's a Beer for those Boffins!
The text talks about a vibration sensor, but all the pictures reference vibration motors.
I didn't think phones had specific vibration sensors, but collected motion data from accelerometers (which would not have the sampling rate for audio).
It sounds more like they're using the motor as a sensor, via an ADC... that's clever on the scale of "interesting, but completely pointless"
Thanks for asking that. I was confused too.
To me a sensor is something that responds to some environmental condition in some way.
The vibration *motor* is NOT a sensor - even though it appears to be being adapter to work as such here.
Agree with other poster - interesting but pointless.
In other news, "researchers" have found a way of stealthily using a smartphone's light sensor as a 1x1 pixel monochrome spy cam! Provided they're given unrestricted physical access to your phone for a few hours in their lab... I'm reasonably sure there are much greater threats to our privacy we need to be made aware of than this twaddle.
Interesting idea, however useful it ultimately ends up being. The main part of their research actually seems to be about regenerating the 'missing' frequencies from the vibration-motor-as-microphone signal rather than the hardware hacking to enable it's use. I notice that their sample voice is quite deep so probably plays to the strengths of the experiment. I wonder how effective it is for a less resonant, higher pitched voice?
What they've *actually* shown is that they can recover speech, specifically, from a very noisy signal (same as quiet) that is heavily band-limited way below what you'd expect, and non-linearly distorted. There's other covert sensors that can give you exactly that input.
There's a couple of very nice papers that experimentally demonstrate moderate sound recovery from smartphone video imagery through windows, of objects within the room. The principle is that something like a Coke can vibrates very slightly, and the straight lines on the object appear very slightly wavy due to camera sequential scan.
This research might improve the speech recovery from such a system - which if you listen to it, is at the level of hearing some syllables and moderately guessing others with more high-frequency components.
Can't you simply use the microphone? Sure, there are permissions governing the microphone, but how many apps have legitimate access to already? And how many apps will be installed on Android that require the permission even though they don't need it?
The difference between "install an app that uses the vibration motor as a sensor/microphone" and "install an app that uses the microphone" is not worth defending. This is like trying to caulk a hairline crack in your home next to an open window that can't be closed.
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