Nerd alert: ecash via sound? \ stacker news ~bitcoin

2733 sats \ 21 comments \ @crrdlx 20 Jun bitcoin

A proof-of-concept to transfer bitcoin sats as ecash via sound using the Cashu protocol.

Ecash can be sent digitally as text data, visually via a QR code reader, physically as a piece of paper with text or a QR printed on it. How about audibly? Can ecash be sent via sound?

There are 21 sats as a cashu/ecash token at https://crrdlx.on.fleek.co/ecashsound/ to the first person to get them. Will this be the "world's first" ecash sent via sound? I don't know. Still, is has a nice ring to it and maybe you can be a small part of ecash/bitcoin history. 😀

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105 sats \ 0 replies \ @BitByBit21 20 Jun

21 sats \ 0 replies \ @03365d6a53 20 Jun

wow, interesting!

10 sats \ 0 replies \ @SatsMate 21 Jun

Make it addictive. People love the clickity clank of the ball on the roullete wheel or the dopamine induced noise on the slot machine lol.

42 sats \ 8 replies \ @crrdlx OP 20 Jun

Update: someone redeemed the cashu token. Ecash-via-sound was successful. 😀

21 sats \ 7 replies \ @Celeste 21 Jun

Hi @crrdlx! Thank you. I find it all super interesting. Your audio file is >60mb, maybe too big in size. There's no need to hear the audio, fldigi have a playback mode. And yes, an earbud to the mic works.

Yesterday 2024-06-20 around 20:04:07 UTC I got the sats. I almost immediately lost them. The cashu.me wallet seed and the 21 sats gone in ramdisk after a reboot :( I have some screenshots.

and

So, today I learned to encode text and generate an audio file. Please take 21 more ecash sats from nc7o5meooayatc3ghedkhfql6iitnigzcj24amhhsqkraxdtcwk6zpyd.onion/21burned_bpsk125.wav

Mode: BPSK, Symbol Rate: 125. Filesize: 7.096.364 bytes The stream falls under "1500". I don't know if I can host it for long, ideally until redeemed.

0 sats \ 6 replies \ @crrdlx OP 21 Jun

I'm happy you received the token and sats. I'm sorry you lost them! I'm guessing you didn't write down the cashu.me seeds. If you did, you should be able to recover them.

The sound file is big, I know. I likely could have played with things to get it smaller, but I wanted to make it so things would be as likely as possible to go through. For instance, the baud rate could be higher (like you have it set) or an mp3 might be smaller (though I got a few errors via mp3 so opted for wav).

That's really neat that you're sending sats via sound too. Your file is no longer there or the link is breaking though...I'm getting a 404 error on Stacker News.

0 sats \ 5 replies \ @Celeste 21 Jun

The url format is incorrect. It should be http://nc7o5meooayatc3ghedkhfql6iitnigzcj24amhhsqkraxdtcwk6zpyd.onion

All was properly wrote down, but then a .gz backup was corrupt. My precious.

0 sats \ 4 replies \ @crrdlx OP 21 Jun

That .onion domain is only available via Tor network. And "wrote down"...on paper, right? Then you could still restore regardless of any ".gz backup" corruption.

0 sats \ 3 replies \ @Celeste 22 Jun

Oh no, correction: nothing was properly wrote down and then the backup failed. Those sats are in stand-by mode until the end of time.

Please try with https://send.zcyph.cc/download/c05e287e1a769bff/#ncMqOlbL5MZi7eZkHQy4lQ The link expires after 100 downloads or 6d 23h 59m

0 sats \ 2 replies \ @crrdlx OP 22 Jun

Yeah, #1 rule in bitcoin/crypto is save your keys. And #2 rule is save them in multiple places and #3 is save them on something that isn't on a device that can fail or get hacked.

Sorry, but as a matter of policy, I'm not going to download something unknown from just somewhere. If it's a sound file, you could place it on a web page and make it playable in-browser. I used the simple code at https://www.w3schools.com/html/html5_audio.asp

100 sats \ 1 reply \ @Celeste 26 Jun

Ain't every downloaded bit unknown and from just somewhere?

One more try, this time the page shows an audioplayer. Sounds good.

https://upload.adminforge.de/r/zsY9eWMxzp#RfYaOcLRlVburMz0G1P4sqJjoBiBY92Y8qTRI9c9sxs=

No more nerds I guess. The sats still waiting.

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0 sats \ 0 replies \ @crrdlx OP 24 Jun

The complete cashu token is below. If you wish, you can copy/paste it into a Cashu wallet. It won't go through, but this shows that it was successful.

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

0 sats \ 7 replies \ @Car 20 Jun

@supertestnet didn't you do this on lightning?

201 sats \ 6 replies \ @supertestnet 20 Jun

@cascdr and @BlueSlime and I made a project last year called Satoshi Jump which can convert any piece of text into DTMF tones (the ones used to transmit phone digits) and then send them to another computer via sound. In theory you can use this to transmit bitcoin transactions and LN transactions via sound, but we didn't do that part, we just transmitted short text messages.

121 sats \ 0 replies \ @cascdr 21 Jun

here's the demo video:

Summary:

The team, Satoshi Jump, aimed to tackle the problem of broadcasting Bitcoin transactions over the radio without internet to widen the network reach and enhance censorship resistance.
They used dual tone technology and digital signal processing in a browser-based offline module to transmit and interpret hexadecimal codes.
The team demonstrated their solution by sending words over the airwaves using tones and showcased the potential for making Bitcoin transactions in areas with limited internet access.
Future work includes improving error correction, increasing transmission speed, and exploring walkie-talkie radio stacks and phone integration for wider accessibility.

TLDR:

Team Satoshi Jump developed a solution to broadcast Bitcoin transactions over the radio without internet.
They used dual tone technology and digital signal processing in a browser-based module.
The team demonstrated the solution by sending words over the airwaves using tones.
Future work includes improving error correction, increasing transmission speed, and exploring phone integration for wider accessibility.
The project aims to enhance Bitcoin network reach and censorship resistance.

Conclusion:

The video showcased the innovative approach of Satoshi Jump in enabling Bitcoin transactions over the radio without internet, highlighting the potential for expanding the network's reach and enhancing censorship resistance. Their future work focuses on improving the solution for faster and more reliable transmission, as well as exploring additional integrations for wider accessibility.

21 sats \ 4 replies \ @megaptera 21 Jun

Would this be possible with a sound that is not possible to hear for humans? e.g. in a specific frequency? Then it could be used so pay contactless between two devices... :)

153 sats \ 0 replies \ @supertestnet 21 Jun

I think it's possible if the two devices (1) are close to one another (2) have the volume turned up (3) use a "regular" speaker + microphone (4) the background isn't very noisy

I doubt it is feasible via walkie talkies. I assume their range of transmissible sounds doesn't include much outside the range of human hearing, plus they transmit lots of static, interference, and environmental sounds which would probably ruin the effect. It's probably not even feasible in a setting like paying for coffee at a starbucks due to too many variables listed above. Humans are bad at following procedures precisely unless they are conscious of the requisite conditions and why they are needed, and I think #1 and #2 would trip normal people up.

E.g. I suspect people would try to pay with headphones plugged in and then not understand why it's not working. Even without headphones, some users would probably turn the volume down if the payment app turned it up without them understanding why. And you can't rely on "just telling them why" because people don't read what their apps tell them, they just complain when they don't work the way they wish things worked.

121 sats \ 0 replies \ @cascdr 21 Jun

It's possible. Phone transducers can send/receive up to around 20kHz.

Most adult humans can't hear beyond about 15kHz.

You'd need to keep in mind transmission distance which decreases with frequency which can be either a feature or a bug.

You can apply the same principles as Satoshi Jump using DTMF + The Goertzel Algorithm for tone detection. DM one of us if you'd like to learn more.

0 sats \ 0 replies \ @Celeste 21 Jun

Would a FM Transmitter work? The devices speak through telepathy.

Specification: Frequency range: 87.5-108MHz / Step Effective Range: 5m Voltage: 5V Distortion degree: 2 percent Color: Black

0 sats \ 0 replies \ @crrdlx OP 21 Jun

My thinking on this question: I don't know the answer, but my gut says it's possible (though not too practical). While futzing with things like psk31, I've noticed that the sound level, even the audible sounds, the volume does not have to be very high at all if the devices are very close. For example, while setting up the 21 sat transfer audio file in the link up above, I used normal earbuds dangling over my laptops mic. I did that because the audio was too annoying my wife would have strangled me. I have rather poor hearing, but I could not audibly hear the sounds even though the data was being transferred earbud-->mic-->Fldigi to decode.

As far as outside the range of normal hearing thresholds, that's probably something for a ham radio person to answer. User bitpunkfm suggested waver (ggwave) over on nostr. I'd never heard of it, but it might be doing what you're describing with "ultrasonic" messages. See youtube vid, the first couple of tx you can hear, the ultrasonic message is at about the 33 second mark.

Convo on nostr: https://njump.me/nevent1qqs953da657ss86eq0dv49d5vrnqu6f70t3k57j6xnaluejaazvs3jqpzdmhxue69uhk7enxvd5xz6tw9ec82c30qgs9pk20ctv9srrg9vr354p03v0rrgsqkpggh2u45va77zz4mu5p6ccrqsqqqqqpfm4nnn