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Show HN: A new protocol for packet radio including ECDSA and compression

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Re: Show HN: A new protocol for packet radio including ECDSA and compression

#31

Post by _9vzr »

leetbulb wrote: post #4

> With amateur packet radio anyone can pretend to be anyone else. With Chattervox, you can be sure you're chatting with the person you intend to. This is a great idea, for both the community and as a hobby project. Has there been any other attempts at similar protocols for amateur radio?

You can run just about anything over AX.25 since it's just the data link layer in the OSI model. You could run HTTP on top of IP on top of AX.25 with TLS/SSL message encryption turned off so you don't run afoul of FCC rules. The authentication would still be there but everything would be in the clear. You could also run IPsec with just the authentication field in the header, no encryption. Even if you didn't want to get that deep into the layers, you can always just pgp sign your messages on packet radio. Depending on the signature length, it could take several extra seconds to send the pgp signature at the typical 1.2Kb/s!

Decreasing the complexity of the stack is a good move forward. The speeds of packet radio require a custom protocol that limits overhead but leaves options for authentication and message signing. Some hams have been using packet radio at wifi frequencies which basically creates a wireless WAN with much higher data rates, making any of the authentication methods much quicker.

Re: Show HN: A new protocol for packet radio including ECDSA and compression

#33

Post by DerekRobot »

trothamel wrote: post #19
brians wrote: post #13

Earlier quoted context omitted.

There are more hams in the US, and more active hams, than ever before. That's a funny sort of dying! Joe Taylor's work on below-the-noise signal extraction has revitalized shortwave: https://physics.princeton.edu/pulsar/k1jt/wsjtx.html , particularly at the nadir of the sunspot cycle. That's a funny sort of dying! Amateur satellites are accessible for $100 in parts: https://www.n2yo.com/satellites/?c=18 ; with the sa…

Is there a good description of what those $100 in parts for satellite work are? Or better yet, something purchasable that's likely to work? I've been wanting to get into it, but I've never found a really accessible guide to getting started in satellite communication.

You could make a good tape measure yagi and use it with a cheap radio like the UV-5R. It needs to be dual-band (440mhz and 2m); AMSATs are usually duplex.

http://theleggios.net/wb2hol/projects/rdf/tape_bm.htm

Re: Show HN: A new protocol for packet radio including ECDSA and compression

#34

Post by mycall »

kam wrote: post #27
mycall wrote: post #6

I would love to another version of this using gnuradio and lime sdr mini (or similar)

This looks like it implements the packet processing only, and suggests using Direwolf as a software AX.25 modem. Direwolf can decode audio piped from rtl_fm or gqrx, so using a SDR is likely already possible for receive; not sure about transmit.

Maybe the Direwolf source code can work via the python calls from gnuradio itself.

Re: Show HN: A new protocol for packet radio including ECDSA and compression

#35

Post by aidenn0 »

vvanders wrote: post #30

Does this do any sort of FEC? One of the things that makes stuff like this tricky(and APRS in general) is that one flipped bit throws off the whole decode. From what I've seen out there would be a 40% improvement[1] in just base APRS if there was some form of basic FEC built into the protocol. Sadly most of "state of the art" is stuck back in the 80s. [1] http://eludium.stensat.org/mcguire/projects/FX-25/FX-25_perf..…

Does AFSK imply the use more than two frequencies? Using 4 or 8 frequencies and trellis modulating should get significant gain (i.e. using 4 frequencies and trellis modulating 1 bit per chip should be more robust than using just 2 frequencies).

Re: Show HN: A new protocol for packet radio including ECDSA and compression

#36

Post by dokument »

Cyph0n wrote: post #2

Cool project! I have always been interested in the amateur radio scene. So encrypting amateur radio comms is illegal in the US? Is there a particular reason for this?

Another reason. If encryption was allowed then you would have a lot of commercial use on public bands but you couldn't enforce it, etc. It would ruin the public bands for everyone.

Re: Show HN: A new protocol for packet radio including ECDSA and compression

#38

Post by tlrobinson »

wedowhatwedo wrote: post #24
emptybits wrote: post #7

Earlier quoted context omitted.

It's also illegal in Canada. With amateur radio "dying" as an interesting hobby (my opinion, but widely held) it is often speculated that if encryption was permitted in amateur radio communications, there would be quite a resurgence in interest. I predict a new generation would start to pick up the hobby and find untold uses (and abuses) for it.

Yes, if encryption was permitted, there would be a ton of interest...by commercial companies. Non-licensed users would out number licensed ones by huge amounts. It would put an end to amateur radio.

Requiring messages be signed by and for keys belonging to licensed amateurs might be sufficient to discourage abuse.

Re: Show HN: A new protocol for packet radio including ECDSA and compression

#39

Post by vvanders »

aidenn0 wrote: post #35
vvanders wrote: post #30

Does this do any sort of FEC? One of the things that makes stuff like this tricky(and APRS in general) is that one flipped bit throws off the whole decode. From what I've seen out there would be a 40% improvement[1] in just base APRS if there was some form of basic FEC built into the protocol. Sadly most of "state of the art" is stuck back in the 80s. [1] http://eludium.stensat.org/mcguire/projects/FX-25/FX-25_perf..…

Does AFSK imply the use more than two frequencies? Using 4 or 8 frequencies and trellis modulating should get significant gain (i.e. using 4 frequencies and trellis modulating 1 bit per chip should be more robust than using just 2 frequencies).

Nope, just two pairs of bell tones on the same frequency.

Simple FEC just works pretty well with parity bits, just needs to be supported on all encoder/decoders.

Re: Show HN: A new protocol for packet radio including ECDSA and compression

#40

Post by emptybits »

brians wrote: post #13
emptybits wrote: post #7

Earlier quoted context omitted.

It's also illegal in Canada. With amateur radio "dying" as an interesting hobby (my opinion, but widely held) it is often speculated that if encryption was permitted in amateur radio communications, there would be quite a resurgence in interest. I predict a new generation would start to pick up the hobby and find untold uses (and abuses) for it.

There are more hams in the US, and more active hams, than ever before. That's a funny sort of dying! Joe Taylor's work on below-the-noise signal extraction has revitalized shortwave: https://physics.princeton.edu/pulsar/k1jt/wsjtx.html , particularly at the nadir of the sunspot cycle. That's a funny sort of dying! Amateur satellites are accessible for $100 in parts: https://www.n2yo.com/satellites/?c=18 ; with the sa…

> There are more hams in the US, and more active hams, than ever before

I apologize for repeating the doom and gloom then, because I know it can be self-fulfilling.

The AARL has optimism but it also tells us net licenses are up http://www.arrl.org/news/more-than-30-000-new-ham-licensees-...

A decentralized, no-carrier/ISP, disaster-tolerant medium for private communication would be amazing.

I am not a licensed ham so this question is naive: If the major concern of allowing private communication over amateur bands is an influx of private commercial communication, then could bandwidth limits, protocols, signatures (amateur-vs-commercial), and enforcement be worth at least a trial? Perhaps on a new or limited existing band?

A government-run experiment to address demand for this limited public resource seems reasonable.

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