Researchers develop acoustic based data transfer system for phones

Technology employs 'self-jamming' for security and could be an alternative to NFC. No word on whether it sounds like the squeal of a 56k modem.

The relevance of this photo is dubious at best, but how could we resist. Image credit: Xiaowei/Wikipedia/Creative Commons licence.

The relevance of this photo is dubious at best, but how could we resist. Image credit: Xiaowei/Wikipedia/Creative Commons licence.

Near Field Communication technologies incorporated in some of the latest smartphones can be used for applications such as contactless payments or data exchange between two devices. Although NFC support has found its way into some apps such as the Commonwealth Bank's Kaching payment system, it's still far from achieving widespread adoption.

One factor in this has been the lack of NFC support even in some leading smartphone models; for example Apple is yet to issue a handset that supports NFC. However, researchers at Microsoft have developed an alternative system that can offer NFC-like capabilities, but without requiring dedicated wireless hardware to make it work.

Instead, their system – which the team at Microsoft Research India, Rajalakshmi Nandakumar, Krishna Kant Chintalapudi, Venkata N. Padmanabhan and Ramarathnam Venkatesan dub 'Dhwani' – uses sound.

Dhwani uses the speaker and microphone on phones to securely exchange data, achieving speeds of up to 2.4Kbps; short of the peak rate of 424Kbps possible with NFC but "sufficient for most existing NFC applications" the researchers write in their paper.

As with NFC, the range of Dhwani is far shorter than Wi-Fi or Bluetooth and will work effectively only over a distance of a few centimetres.

In addition to being software-based and hence not requiring specialised hardware for transfers, the researchers also believe that it is more secure than NFC. The researchers managed to monitor NFC communications from around 20-30cm away, and believe that with a more sophisticated antenna monitoring from distances up to a metre may be possible.

For security Dhwani relies on a 'JamSecure' approach which "uses self-jamming coupled with self-interference cancellation at the receiver" to protect any data transmissions.

Essentially this relies on the receiving device transmitting pseudorandom noise while the transmitting device is sending data. Then this noise can be compensated for by the receiver.

Any eavesdropping device would be able to only listen to a combination of the pseudorandom noise and the (data transmitting) noise from the sending device.

The basis of Dhwani's communication system is an 'Acoustic Software Defined Radio'. The researchers conducted tests in noisy environments and established that 6KHz was the lower limit for the system, below which typical ambient noise would interfere with transmissions.

Tags mobilitysmartphones

More about AppleCommonwealth Bank of AustraliaMicrosoftNFC




Sorry if I get this wrong but in my eyes this really is exact the same incredibly stupid unsafe technology as NFC is.
They believe that NFC could be listened to from 1m distance but their new audio device is safer? Really?
Did they ever heard of the invention of a laser- or directional microphone?

What about the "self jamming" part.
First option: My device jams itself based on a random algorithm and alternating frequencies so the responding device has three possible setups:
A): Its has a list on possible combinations
B): There is some kind of handshake at the start of communication / or identification what kind of device is trying to interact and the responding device will behave based on this information
C): The responding device is pretty much powered up and will be able to solve the anti jamming part based on trial and error in an appropriate time

Second option: My device says hello before jamming itself to do a handshake

Please don`t get me wrong I don`t say that I am able to just walk up listen a second to one of these and laugh at them and steal their money. But I am a bit irritated that they claim it way more secure than NFC (btw I won`t ever trust my money to my phone anyway). Everybody could listen to it except they use some special frequencies but this will also open gates for attacks because no one will hear if there are someone doing an attack at the very moment.

Pfuuh, feeling better right now
Thanks for reading (if you did ^^ )



John, what you're missing is that the reciever is putting out the jamming signal. Since it knows what the jamming singal is, the reciever can cancel it out. The transmitter has no need to cancel the jamming signal.

Directional mics are still a problem though



@ Bilateralrope
I am afraid I don`t get it. Does it make a difference which device sends the jamming signal? As long as there are a two way communication there still has to be some kind of verification what data is crap and what is real info.
If it`s only one way communication or a walkie talkie like technique (only one speaks at the time and the other listens and jamms then speaking and jamming switch rolls) this will work.
And thats probably the way how they do it ... argh okay I got it. Just realized that realtime two way speaking sounds not very clever at all. Because there`s no reason the receiver should response while speaker still talks.

thanks for your response



Looks like somebody is discovering hot water again.
Margento invented and patented this back in 2003 and it is already being commercially used by millions of people for almost a decade in parts of East Europe and the Middle East.



@ Dani
Do you know if they use hearable frequencies or more like infra or ultrasoinc sound? (don`t really know what mobiles are capable of)
All videos I could find about Margento where like "hey look we are so super cool and it`s super easy to use" combined with annoying elevatormusic instead of showing how it really works.

dr. nice


Dani: Margento sends data over the audio channel of a normal mobile phone call, while this here works with a real microphone and speaker.
Johny: The receiver sends the noise, but not to the transmitter. it's just to jam any outsider. it's "secure" as long as it's not possible to discern the two audio sources.

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