BackDoor: Making microphones hear inaudible sounds

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Consider sounds, say at 40kHz, that are completely outside the human's audible range (20kHz), as well as a microphone's recordable range (24kHz). We show that these high frequency sounds can be designed to become recordable by unmodified microphones, while remaining inaudible to humans. The core idea lies in exploiting non-linearities in microphone hardware. Briey, we design the sound and play it on a speaker such that, after passing through the microphone's non-linear diaphragm and power-amplifier, the signal creates a "shadow" in the audible frequency range. The shadow can be regulated to carry data bits, thereby enabling an acoustic (but inaudible) communication channel to today's microphones. Other applications include jamming spy microphones in the environment, live watermarking of music in a concert, and even acoustic denial-of-service (DoS) attacks. This paper presents BackDoor, a system that develops the technical building blocks for harnessing this opportunity. Reported results achieve upwards of 4kbps for proximate data communication, as well as room-level privacy protection against electronic eavesdropping.

Original languageEnglish (US)
Title of host publicationMobiSys 2017 - Proceedings of the 15th Annual International Conference on Mobile Systems, Applications, and Services
PublisherAssociation for Computing Machinery, Inc
Pages2-14
Number of pages13
ISBN (Electronic)9781450349284
DOIs
StatePublished - Jun 16 2017
Event15th ACM International Conference on Mobile Systems, Applications, and Services, MobiSys 2017 - Niagara Falls, United States
Duration: Jun 19 2017Jun 23 2017

Publication series

NameMobiSys 2017 - Proceedings of the 15th Annual International Conference on Mobile Systems, Applications, and Services

Other

Other15th ACM International Conference on Mobile Systems, Applications, and Services, MobiSys 2017
Country/TerritoryUnited States
CityNiagara Falls
Period6/19/176/23/17

ASJC Scopus subject areas

  • Information Systems
  • Computer Networks and Communications
  • Software
  • Hardware and Architecture

Fingerprint

Dive into the research topics of 'BackDoor: Making microphones hear inaudible sounds'. Together they form a unique fingerprint.

Cite this