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Decimen Optical Transfer: fountain-coded QR file transfer

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Re: Decimen Optical Transfer: fountain-coded QR file transfer

#41

Post by stronglikedan »

pjc50 wrote: post #29
elric wrote: post #2

Neat, finally an easy way of transferring files between devices that doesn't rely on online services -- no clue why we didn't solve that ages ago. Adding encryption shouldn't be hard, as long as you can communicate the keys out of band. Could probably achieve the same result using audio instead of video, but maybe that would be too annoying?

> between devices that doesn't rely on online services -- no clue why we didn't solve that ages ago Airdrop is a thing, but remember that Android phones are controlled by the online services company that wants you to use online services.

> by the online services company that wants you to use online services

Do you mean the one that went to all the trouble to reverse engineer Airdrop so that people could access Apple's vendor-locked walled garden without the use of online services?

Re: Decimen Optical Transfer: fountain-coded QR file transfer

#42

Post by upofadown »

>Neither mode is encrypted: whatever is on the sending screen is readable by any camera pointed at it.

Something like this would be good for transferring the public key(s) associated with some cryptographic messaging identity. This would allow that to happen entirely offline. The optical nature of the transfer would prevent a potential MITM. The idea that an identity is being transferred would be fairly easy to impart to the user.

So the lack of encryption would be a feature and not a bug. This would enable later encryption which could then use any medium for the transfer in a completely secure way.

Re: Decimen Optical Transfer: fountain-coded QR file transfer

#43

Post by inigyou »

cwmoore wrote: post #39
inigyou wrote: post #33

Earlier quoted context omitted.

I bet they don't, because they didn't know about it or didn't think of it. I know GPS is a slow repeating stream (the ephemeris repeats every 30 seconds and the almanac every 12.5 minutes) but that probably came before fountain codes.

Speculation about the past is probably unnecessary. Reed-Solomon/erasure codes have been in operations since the 1960s https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_cor...

Although a repetition of any high-rate erasure code can act similarly to a fountain code, they aren't classed as such.

Re: Decimen Optical Transfer: fountain-coded QR file transfer

#45

Post by orev »

pjc50 wrote: post #29
elric wrote: post #2

Neat, finally an easy way of transferring files between devices that doesn't rely on online services -- no clue why we didn't solve that ages ago. Adding encryption shouldn't be hard, as long as you can communicate the keys out of band. Could probably achieve the same result using audio instead of video, but maybe that would be too annoying?

> between devices that doesn't rely on online services -- no clue why we didn't solve that ages ago Airdrop is a thing, but remember that Android phones are controlled by the online services company that wants you to use online services.

LocalSend has been working great for me across different types of devices.

Re: Decimen Optical Transfer: fountain-coded QR file transfer

#46

Post by ErroneousBosh »

myself248 wrote: post #20
ErroneousBosh wrote: post #7

Earlier quoted context omitted.

You can do PSK31 across a room with just audio, but it is a kind of annoying noise after a while. It's interesting that you learn to recognise patterns in the burbling tones after a while. "CQ CQ CQ" is very distinctive and after a while you can hear your own callsign in it. I guess it's not that different to very fast Morse.

Or SSTV! I recall a demo years ago where someone had SSTV running between a speaker at the focus of a small dish, across to the room to another small dish with a microphone...

There's a track on an Aphex Twin CD (yeah well it would be, eh?) called Bonus High Frequency Sounds that's an SSTV pic of him in his studio.

Re: Decimen Optical Transfer: fountain-coded QR file transfer

#47

Post by inigyou »

inigyou wrote: post #43
cwmoore wrote: post #39

Earlier quoted context omitted.

Speculation about the past is probably unnecessary. Reed-Solomon/erasure codes have been in operations since the 1960s https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_cor...

Although a repetition of any high-rate erasure code can act similarly to a fountain code, they aren't classed as such.

(or is it low-rate? one of those)

Re: Decimen Optical Transfer: fountain-coded QR file transfer

#48

Post by jodrellblank »

bigiain wrote: post #5
elric wrote: post #2

Neat, finally an easy way of transferring files between devices that doesn't rely on online services -- no clue why we didn't solve that ages ago. Adding encryption shouldn't be hard, as long as you can communicate the keys out of band. Could probably achieve the same result using audio instead of video, but maybe that would be too annoying?

I had a Timex Data Watch over 30 years ago. https://en.wikipedia.org/wiki/Timex_Datalink It'd transfer phone numbers and calendar entries to the watch by blinking the screen of your computer. Kinda a 1 pixel version of this. (I wonder where that ended up? From memory I threw it in a drawer when I finished the Windows 95 project I'd been working on, and switched to Mac. There was no Mac software to talk to it.)

Psion Series 5 and other PDAs had infra red (IrDA) ports for 'beam'ing contacts, transferring files, printing, etc.

1998 - https://groups.google.com/g/comp.sys.psion.misc/c/oFtTHyx6IR...

1994 - https://en.wikipedia.org/wiki/IrDA

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