Bitcoin Forum

I was wondering if there would be a way to transmit bitcoins by sound.  I know you can send and recieve by scanning QR codes but it seems like that could easily be converted to sound.  

I guess it would sound like a 300 baud modem.  Also I'm not sure what real world purpose this would have.  Just wondering if its been talked about.

you mean hold your device close to a terminal and it plays a sound it picks up? i could see that working.

Yep exactly like that.  Maybe you could even transfer them through lan lines like that I dont know. lol

like dialup? that would work, it transfers data like any other type, just really slow, slower than 56k so like 10-30 seconds per block or more even.

Actually I dont know what I'm thinking.  Not like dialup though.  What if a radio station wanted to give out 10 free bitcions at some point during the day.  You'd have to be waiting with your smartphone up to the speaker to hear the garbled mess they send through.  Once your phone picks up the garbled mess it decodes it and you get your bitcoins. 

Not sure if something like that would work with blockchains and what nots.  Just an thought.

 

the more garbled the sound gets, the longer it will take to reliably send. on dialup you only get 56k on a good day, and your hooked directly up to the line. but its not much text so it may only take like 1-2 seconds to get. but i dont see why it would not work, thats pretty much just like dial up, changing data into sound, then changing the sound into data on the other end. that's how this and dial up work.

If it has to be audible, the max bitrate is about 3~4Kbps IIRC. Or 0.5KB/s, no idea how large is a bitcoin send/receive packet though.

You could send the private key for a wallet. That, or a mtgox voucher would probably be the most efficient method.

At first i thought this was about performing transactions using audio to transport the transaction request for the first time, for things like a blind client in a mobile that doesn't got a fresh blockchain, only the private key of an address that was expected to have money (so you could for example use a cheap(er) device that doesn't got an internet connection, walk to a vending machine, press a couple buttons and place the device against the mic of the vending machine, and the vending machine would relay the transaction to the internet); i'm not quite sure now....

"My address sounds better than yours" :D
Hey, we have some other technologies to use... like Bluetooth or wi-fi.. even IR... Transmission of information using sound is stone age...

Thanks for crushing my dreams of winning 10 btcs by holding my phone up to the speaker of my favorite classic rock station bro.

I read somewhere on these forums (or an article) that Bitcoins could even be sent via smoke signal. All they are is a code, so in theory one could transfer that code in a million creative ways =)

Telephone and AM/FM radio coverage is more complete than BT/Wifi/IR so there could be some situations where being able to transact via audio might be useful. Not a lot but possible. :D

Except for the fact that the vast majority of cellphones on this planet do NOT support bluetooth OR wifi, call it 'stone age' but if it works there is no need for something fancy like bluetooth or wifi.

But can you install custom software in such devices? And are they even powerful enough to decode data from the audio stream without the addition of a dedicated chip?

Nice idea, but to effectively transfer to cell-phones (even very old ones): just use SMS :)

But for smartphones it would probably be trivial to make a little app that does exactly what you propose.

It's funny, because I have been thinking about this EXACT thing for the past week. I was thinking that there could be a bitcoin transfer protocol which would use an audio signal to send bitcoins to a near by device. Here is what i wrote up over the past week:

While thinking about how to simplify bitcoin, I stumbled upon something. I don't know how unique this is or how well it could work, but here it is.

Cell/Smart phones are some of the most abundant devices around, however, they typically do not support many features due to hardware limitations, bluetooth or wifi are out of the question for the vast majority. However, there are two components that all cellphones have: a microphone and a speaker. What if we could use these to facilitate in person bitcoin transactions?

The following is my attempt at creating a protocol for audio bitcoin transfers. It is not limited to cellphones nor is it limited to an audio signal.

1) Protocol initiation signature + encryption flag
Enabled devices could be continuously listening for an audio signature which would indicate a bitcoin transaction request. And an encryption flag, responding to this flag with an encrypted acknowledgement would allow you to connect ONLY with a trusted party.

2) Bitcoin address  - an appropriate address is sent/requested as a part of the header

3) BTC amount - a number indicating how many bitcoins will be involved in this transaction. Entering a wild character (*) could allow the other party to choose how much they want to send.

4) Name/Message - a limited length name or message to help manage an address book or to say something like 'thank you'


5) Confirm and close transaction.

There could be some sort of volume control to help prevent interference with other devices near by.

Example of use 1
I go shopping in a super market, I pick out my products and then go up to the cash register, the cashier and the cashier scans all my products and hits the request payment button, immediately my device vibrates to alert me of a payment request, I swipe 'O' on my touch screen to accept the request and the transaction is done!

Example of use 2
A charity wishes to collect donations for their cause or maybe a politician wants to raise some funds for their campaign. While doing a presentation, they broadcast their address and all listening devices are alerted of an incoming address, to which they can send any btc amount.

You'd probably have a hard time running any piece of software on devices that neither have bluetooth nor wifi.
The idea is nice, but I think it's simply not practical for old cell-phones to use Bitcoin in any way.

As for smartphones - sure, go for it!

all we need is a small door, and we're in! Sure, it may not be as easy to program an old phone as it is a current gen smartphone, but thats no excuse not to try! http://www.cellphonehacks.com/

cool man glad to see I wasn't the only one. lol  Although you're alot more technical than me.  Looks good.

Well, maybe there are few phones today without wifi/bluetooth that could also decipher a audical bitcoin-adress, however, they could be built. A blutooth cirquit is a lot more expensive than a speaker/microphone. The bitcoin model has huge potential in areas where the financial services are not that well developed yet.

The idea is great, however sound should only be the vector for a message following the standard bitcoin URI https://en.bitcoin.it/wiki/URI_Scheme

This way we always have the same kind of message in QR codes, audio messages, smoke transmissions.

I guess for sound there would need to be a lot of redundancy and error correction in the transmission. However I love the idea, it's how podcasts could hide their donation requests, radio could do so too..

Only bitcoins?

Ahem... everything digital can be sent via smoke signal and is a code.

A binary code, 0 or 1.

Every computer work with 0 and 1, that's the fundamental point of the digital signal theory  :D So you could make a computer what work via smoke signal if you want... sure it will be a bit slow...  :D

sure you can transfer BTC by sound. just yell really loud: I NEED MOARRR COINZ!!!  :D

Sure it is. SMS is already used extensively for micropayments. See this report (http://www.infodev.org/en/Document.43.html) about its use in the Philippines for an example. I agree the end-user wth a prepaid mobile isn't personally going to be running a bitcoin wallet on his phone, but a bitcoin interface could get incorporated into the system by the carrier in order to facilitate transactions throughout a wider sphere than currently available. Just give those developers a bit of time. . . .

They would need access to some sort of network once in a while. I'm sure the technical side could be figured out if there was some real interest in this.

This will not be possible, beacause there are to many disturbing frequencies.
imagine: your in a supermarket and there's the piip from the cash register, people talking, baby crying, the videocamere who makes piiip all the time, and some advertisement, ...

there are so many possibilities who can be emmittet in the frequence of the signal, that the transaction via sound will not function really good.

-> possyble it functions if you take high frequencies, low are easier disturbable. best will be, that it is so high, humans cant hear it.
(ooh but dogs can hear and bite)

Not possible on most phones if I'm not wrong. The speakers in there are intended only for human vocal range so they don't do very low or very high audio frequencies very well. It's probably easier to do high than low due to the physical size, but not likely so high humans can't hear it.

As for interference, I believe there are established signal processing methods for dealing with those as long as they don't completely drown out the signal. Shouldn't be a problem if the two devices are close together and directed at each other specifically.

What gets me is that thinking deeper, there might not be a practical situation where such a transfer could be authenticated anyway.

That's strange, voice search on my phone works flawlessly. Anyway, the only thing that really determines whether something is possible or not is the will of the developers and the people influencing the developers. Just like the faith of bitcoin will be determined by its community.

The carriers could implement their own system to allow instantaneous transfers. All the bitcoins could be sitting in a single account at the carrier, and all the transactions within their network could simply be entries in a database. Again, all that we need is a will, and the way will show up.

Isn't this like a digital fax over telephone lines? You have a bunch of binary data converted to analog tones and sent over cheap and low quality cable to be reinterpreted on the other end with good accuracy?  A wallet could be converted to an image through Paperbak, sent over lines or by speakers using something similar to fax specifications, the image then reinterpreted and converted back to a file by Paperbak on the receiving terminal. The file itself could easily be encrypted and made redundant to ensure secure and reliable transfers. Since you're sending a wallet, the receiving party, upon opening the wallet could immediately transfer the received wallet to their personal wallet, thereby preventing double spending. I'm sure there's a much better way to send the data than Paperbak...or sound for that matter, just saying it's doable.