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Gyrophone: Eavesdropping Using a Gyroscope

Talkat Black Hat Europe 2014 · 2014-10-14..10-17· [security]
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Claim: phone gyroscopes pick up acoustic vibrations so apps or webpages that need no mic permission can eavesdrop. Experimental setup uses speakers and a phone, TI Digits corpus, MFCC and spectrogram features, SVM/GMM and dynamic time warping, plus preprocessing (upsample, silence removal). OS limits sampling to 200 Hz on Android and 100 Hz on iOS (hardware can do ~8 kHz); aliasing yields usable info. Results: 84% gender ID, single-device speaker ID up to 65% and isolated-word 26% speaker-independent (65% speaker-dependent), two devices reach 77%. Proposed defenses: OS/hardware low‑pass or permissioned high-rate access.

AI-written summary · about

  1. 0:00Intro
  2. 0:54INTRODUCTION - YAN MICHALEVSKY
  3. 2:51MICROPHONE ACCESS
  4. 4:56GYROSCOPE ACCESS BY A BROWSER JAVASCRIPT CODE EXAMPLE
  5. 5:18MEMS GYROSCOPES
  6. 7:41GYROSCOPES ARE SUSCEPTIBLE TO SOUND
  7. 9:18GYROSCOPES ARE (LOUSY, BUT STILL) MICROPHONES
  8. 11:46SOFTWARE LIMITATION OF THE SAMPLING RATE
  9. 12:13SAMPLING FREQUENCY LIMITS
  10. 14:19THE EFFECTS OF LOW SAMPLING FREQUENCY SPEECH SAMPLED AT 8,000HZ
  11. 17:35WE CAN SENSE HIGH FREQUENCY SIGNALS DUE TO ALIASING
  12. 18:53EXPERIMENTAL SETUP
  13. 20:03SPEECH ANALYSIS USING A SINGLE GYROSCOPE
  14. 23:04PREPROCESSING • All samples are converted to audio files in WAV format
  15. 24:16FEATURES • MFCC-Mel-Frequency Cepstral Coefficients • Statistical features are used mean and variance
  16. 26:27CLASSIFIERS
  17. 27:37DYNAMIC TIME WARPING
  18. 28:58GENDER IDENTIFICATION
  19. 29:30WE CAN SUCCESSFULLY IDENTIFY GENDER
  20. 30:17SPEAKER IDENTIFICATION
  21. 30:51A GOOD CHANCE TO IDENTIFY THE SPEAKER
  22. 31:54ISOLATED WORDS RECOGNITION SPEAKER INDEPENDENT
  23. 34:54HOW CAN WE LEVERAGE EAVESDROPPING SIMULTANEOUSLY ON TWO DEVICES?
  24. 36:10SIMILAR TO TIME-INTERLEAVED ADC's
  25. 37:25NON-UNIFORM RECONSTRUCTION REQUIRES KNOWING PRECISE TIME-SKEWS
  26. 40:43PRACTICAL COMPROMISE Interleaving samples from multiple devices
  27. 41:15EVALUATION Tested for the case of speaker dependent word recognition
  28. 42:15FURTHER ATTACKS
  29. 43:26AMBIENT SOUND RECOGNITION
  30. 44:05SOFTWARE DEFENSES
  31. 45:15HARDWARE DEFENSES
  32. 46:09CONCLUSION
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