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I'm working on an app that passively picks up ultrasonic tones generated by SilverPush and sends out garbled data. The biggest issue with blanket interference

by Cyph0n 10y ago

I'm working on an app that passively picks up ultrasonic tones generated by SilverPush and sends out garbled data. The biggest issue with blanket interference across the entire ultrasonic band is that there are some legitimate uses that don't involve cross-device tracking. That's why we need to address this issue by selectively interfering with only known tracking schemes.

rocky1138 10y ago
Can you elaborate on which legitimate uses you had in mind?
- Cyph0n 10y ago
  These are two services I know of that use it for cool stuff with user permission: * Authentication: http://www.copsonic.com/ http://www.copsonic.com/ * Shopping deals: http://www.shopkick.com/ http://www.shopkick.com/
- kimburgess 10y ago
  Anything that requires the ability to detect if it's in the same physical space as another device / item of interest. Some common examples are: * guest mode discovery on a Chromecast * pairing to videoconference system (both Cisco and Polycom do this in their current gen devices), building control, wireless presentation system etc * a means for transmitting a 2FA code from a personal device for auth / payments * micro-location service - particularly for temporary events or spaces where BLE is not possible (e.g. embedded in FOH audio at different stages at a music festival) * proximity based peer discovery for mobile games You'd be surprised at how common a technique it is. I regularly face issues with environments that have had enough different devices all attempting to use some form of ultrasonic pairing / localisation etc that there's issues with interference.
secfirstmd 10y ago
Where can we follow this project?
- Cyph0n 10y ago
  It's currently a course project we're working on. I will post it to HN once it's in a "good enough" state.
TD-Linux 10y ago
Do you have details on the encoding? I'm a bit suspicious of it being actually ultrasonic (device microphones often filter at 20khz or below) - seems more likely it would be audible spectrum noise with a ton of FEC.
- Cyph0n 10y ago
  They map each letter (A-Z) to a single frequency. The range is around 18-19.5 kHz. As far as I know, this range is inaudible to most adults. I couldn't hear it for example. Of course, I may be using the term ultrasonic incorrectly. Some preliminary work was done last year to reverse SilverPush[1], but my group and I are planning to take it further. [1]: https://github.com/MAVProxyUser/SilverPushUnmasked https://github.com/MAVProxyUser/SilverPushUnmasked
- moreati 10y ago
  I can't speak for SilverPush, but Google Tone definitely has an Ultrasonic component [1] as does a version of Chirp [2]. Both work through consumer grade speakers/DACs/devices. [1] https://www.reddit.com/r/AskEngineers/comments/374876/lets_talk_about_google_tone/ https://www.reddit.com/r/AskEngineers/comments/374876/lets_t... [2] https://vimeo.com/177586203 https://vimeo.com/177586203

by Cyph0n 10y ago

rocky1138 10y ago

Can you elaborate on which legitimate uses you had in mind?

Cyph0n 10y ago
These are two services I know of that use it for cool stuff with user permission: * Authentication: http://www.copsonic.com/ http://www.copsonic.com/ * Shopping deals: http://www.shopkick.com/ http://www.shopkick.com/
kimburgess 10y ago
Anything that requires the ability to detect if it's in the same physical space as another device / item of interest. Some common examples are: * guest mode discovery on a Chromecast * pairing to videoconference system (both Cisco and Polycom do this in their current gen devices), building control, wireless presentation system etc * a means for transmitting a 2FA code from a personal device for auth / payments * micro-location service - particularly for temporary events or spaces where BLE is not possible (e.g. embedded in FOH audio at different stages at a music festival) * proximity based peer discovery for mobile games You'd be surprised at how common a technique it is. I regularly face issues with environments that have had enough different devices all attempting to use some form of ultrasonic pairing / localisation etc that there's issues with interference.

secfirstmd 10y ago

Where can we follow this project?

Cyph0n 10y ago
It's currently a course project we're working on. I will post it to HN once it's in a "good enough" state.

TD-Linux 10y ago

Do you have details on the encoding? I'm a bit suspicious of it being actually ultrasonic (device microphones often filter at 20khz or below) - seems more likely it would be audible spectrum noise with a ton of FEC.

Cyph0n 10y ago
They map each letter (A-Z) to a single frequency. The range is around 18-19.5 kHz. As far as I know, this range is inaudible to most adults. I couldn't hear it for example. Of course, I may be using the term ultrasonic incorrectly. Some preliminary work was done last year to reverse SilverPush[1], but my group and I are planning to take it further. [1]: https://github.com/MAVProxyUser/SilverPushUnmasked https://github.com/MAVProxyUser/SilverPushUnmasked
moreati 10y ago
I can't speak for SilverPush, but Google Tone definitely has an Ultrasonic component [1] as does a version of Chirp [2]. Both work through consumer grade speakers/DACs/devices. [1] https://www.reddit.com/r/AskEngineers/comments/374876/lets_talk_about_google_tone/ https://www.reddit.com/r/AskEngineers/comments/374876/lets_t... [2] https://vimeo.com/177586203 https://vimeo.com/177586203