5 ms·

Sounds plausible to me. The question is whether anyone is really using this technique. Sounds like it would require nontrivial bandwidth and analysis.

• enriquto 5y ago
  > The question is whether anyone is really using this technique. No. This is not at all the question. A possible privacy breach is a serious issue, regardless of whether there is a working POC. If this data is somehow compromised, a stalker could get your identity just by following you a few minutes on the street.
  • vletal 5y ago
    Sure, but the article makes it seem that this is a thing done in a wild on a mass scale which is implausible.
  • charcircuit 5y ago
    a stalker wouldn't be able to accelerate the same as you
    • shagie 5y ago
      If they were on the same public transport vehicle, that would likely be a different situation.
• pantulis 5y ago
  Which also means reduced battery.
  • Nextgrid 5y ago
    Most of the aforementioned apps already have autoplaying media and/or keep the camera running in the background (officially for quicker access to it when the user opens the camera view, as it normally takes a second or so to initialize it). Seems like collecting accelerometer data is a drop in the bucket in comparison.
• Nextgrid 5y ago
  I recall that Snapchat explicitly mentioned accelerometer data in their privacy policy - why would you mention it unless you did or have plans to use accelerometer data in the future? I don't think it would require significant bandwidth; the data is just integers which can be collected, compressed and uploaded asynchronously (as part of another heavy upload such as someone sending a picture). The analysis part could be similar to how Shazam works, but that can be done on the server side so on-device performance isn't a concern.
• jcranberry 5y ago
  A single simple would be three doubles and a timestamp (64 bit int). Accelerometer max update rate is 100hz. So all possible samples each second would be 3200 bytes. So bandwidth doesn't appear to be a big issue.