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A decentralized peer-to-peer messaging application that operates over Bluetooth

bitchat.free

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Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#301

Post by heisenbit »

rm30 wrote: post #260
digiown wrote: post #224

Earlier quoted context omitted.

Will the walkie talkies work if there are hundreds in a small area all transmitting data with each other? Besides, there's just not that much bandwidth there.

The smartphone is just an advanced walkie-talkie, currently limited only by the mobile operator, the law, the radio chipset, and the OS. In a true emergency, who can stop you from modifying that architecture? Once you treat the device as an independent radio node (using its DSP power to run custom modems) you can establish a mesh network with a range of several kilometers. We have a '4x4 car in our pockets; we’ve jus…

The smartphone is talking to a highly sensitive receiver fed by a large sensitive antenna listening carefully in the direction of the smartphone. The base station is transmitting back a carefully directed beam with orders of magnitude more power than a smartphone. The system is highly asymmetrical. Ohh and maybe there is not one but many base stations talking concurrently to the smartphone so that if one looses some data the flow is maintained.

Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#302

Post by rm30 »

catlifeonmars wrote: post #291
rm30 wrote: post #289

Earlier quoted context omitted.

I was pushing on the walkie-talkie case to gain the maximum results from existing phones, that's a true emergency case. You’re absolutely right that the 5G/LTE baseband is a black-box nightmare to repurpose. But I’m not looking to hack the cellular modem; I’m looking for the dormant '4x4 car' already available. For instance, many chipsets have an integrated FM receiver that is essentially a high-sensitivity VHF radio…

> For instance, many chipsets have an integrated FM receiver that is essentially a high-sensitivity VHF radio. By taking the raw audio output and applying a Software Modem (AFSK/FSK) in the user-space, you bypass the kernel/firmware complexity entirely. You don’t need to sideload a modem driver if you treat the audio jack or the internal FM bus as your physical layer. This is fascinating. Happy to do the research mys…

I'm glad you find it interesting. I developed the theory at university, studying how ASK and FSK modems work. To build this, you’ll need to understand the Shannon-Hartley theorem, band-pass filtering, Fourier transforms, and convolution.

For the practical 'how-to,' I recommend studying GNU Radio and SDR++; they show how to process IQ data or raw audio streams directly, and for sure there are other libraries. On the 'ancestor' side, look at the AX.25 Packet Radio protocol and AFSK (Audio Frequency Shift Keying). These are the same 'softmodem' principles used in FidoNet nodes decades ago.

GSM Arena can help you find phones with integrated FM receivers. You'll notice that many features are market-dependent, meaning: the receiver is often physically present but simply disabled by software.

Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#303

Post by barbs »

rm30 wrote: post #244
nicois wrote: post #26

One missing feature: deferred message propagation. As far as I understand, while messages will be rebroadcast until a TTL is exhausted, there is no mechanism to retain in-transit messages and retransmit them to future peers. While this adds overheads, it's table stakes for real-life usage. You should be able to write a message and not rely on the recipient being available when you press send. You should also be able…

I’ve read all the posts and, as the 'old man of the village', I would suggest taking a look at FidoNet. It was running 40 years ago, for more than a decade, before the internet was available to the average person. Store-and-forward, hierarchical organization, scheduled transmissions, working over dial-up and radio links, everything is there. There is nothing new to invent, and it was far more reliable than the 10m re…

It looks like Secure Scuttlebutt may also be relevant here, as it was designed with unreliable networks in mind.

https://en.wikipedia.org/wiki/Secure_Scuttlebutt

Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#304

Post by eddythompson80 »

foltik wrote: post #235
jansper39 wrote: post #226

Earlier quoted context omitted.

Personally, the additional complexity and overheads required for a P2P phone network is not worth while and I'm not sure it would fix that many problems that haven't already been fixed with walkie talkies.

Not worthwhile? “It’s too hard” isn’t a great argument for why our phones should just become useless during power outages, natural disasters, ..

It’s not “too hard”. It’s physically impossible without regulation. There is but one limited RF spectrum that we all share. One bad actor (intentional or misconfigured) can render the entire RF spectrum in their area unusable. The radius of their impact only depends on how much kWHs they have access to and it doesn’t take much to cripple radio communication in a large metropolitan area.

Until some clever cookie can figure out some way to utilize string theory’s extra dimensions for sending signals and then every body can have their own dimension to mess with, collective regulation on broadcasters is the only feasible way.

Nothing is stopping you from getting an HT for communication during power outages, natural disasters, etc. You just have to get a license to make sure you don’t actively harm everyone who is sharing the same spectrum with you especially during said natural disaster.

Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#305

Post by anigbrowl »

gloxkiqcza wrote: post #6
jagermo wrote: post #3

I don't know. I do not like Jack Dorey's involvement. Not a big fan of his. I'd rather use Briar ( https://briarproject.org/ )

There’s no app for Apple platforms making it a lot less useful.

Buy a cheap shit android phone for under $100 and never associate it with a SIM

Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#306

Post by kyrofa »

fenwick67 wrote: post #286
shimman wrote: post #281

Earlier quoted context omitted.

Or even better, where is the tech that can do this disregarding the law? Let's not act that something being illegal never stopped it from achieving mass adoption.

Well obviously cell phones have very powerful tx/rx so my question would be "what is stopping us from using this for p2p", I assume the answer is we don't have software access to the radio, and I assume that's for regulatory reasons but idk

That's not actually true: cell phone rx/tx power is quite low. We can get away with that because all they need to do is get to the nearest tower, which has a ton of power, sensitive antennas, and is very tall. Amateur radios have far more power available to them, but any "p2p" (i.e. simplex in amateur radio) runs into normal RF issues, like obstacles and interference. If you used the existing radios in cell phones to communicate directly with other cell phones, you wouldn't get very far. Even amateur radios, with all their power, use repeaters to the same effect as cell towers.

Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#308

Post by joecot »

maqp wrote: post #10
gloxkiqcza wrote: post #6

Earlier quoted context omitted.

There’s no app for Apple platforms making it a lot less useful.

That's probably because AFAIK Apple doesn't allow process forking, making any Tor-based messenger almost impossible to run as Tor would have to run as part of the main thread.

It's because iOS needs push notifications to resume background apps, and there's no secure way to do the push notifications

https://code.briarproject.org/briar/briar/-/wikis/FAQ#will-t...

Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#309

Post by spockz »

api wrote: post #176
spockz wrote: post #150

Earlier quoted context omitted.

Wouldn’t that bring the wrath of mobile carriers around the world on their back? If there is a decentralised system that doesn’t require infrastructure , what is left to monetise?

Range? Bandwidth? A solution like that would work only in limited circumstances. It’d be neat but no replacement for cellular.

Sure. But if you have a semi reliable way of getting messages to loved ones either through the distributed net completely or using a satellite hop somewhere, then you have captured a big chunk of what people really want. When you are at home you can just use your WiFi.

At least in my case, I’m just using messages on the road. Obviously it’s not going to be a solution for sparsely populated areas.

Re: A decentralized peer-to-peer messaging application that operates over Bluetooth

#310

Post by lxgr »

lormayna wrote: post #297
lxgr wrote: post #242

Earlier quoted context omitted.

Both not true. Both European PMR446 and the US FRS are limited to 0.5 W; GSM uses four times that. There are walkie-talkies with very small antennas too. The limiting factor is line-of-sight, in any case. If you're fine with less than real-time audio, you can get much, much smaller and low power.

1) LTE frequencies are in the frequency intervals 600—900Mhz, or over the Ghz. Higher frequency means smaller antennas. 2) 5G cells are small and very dense, this means less power consumption. 3) LTE and 5G are based on CDMA, a technology that is way more efficient in term of bandwidth efficiency than the FM modulation used by a walkie talkie

> 5G cells are small and very dense

Not necessarily. In rural areas and using low frequencies, I believe they can even be larger than GSM.

> LTE and 5G are based on CDMA

No, the last CDMA based cell standards were 3G/UMTS and the Qualcomm equivalent (CDMA2000 or what it was). From then on, it’s all been OFDM.

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