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Comment by mikegioia | Hacker News Reader

This is really cool. The article mentions that encryption is illegal over these radio frequencies, but why is that? Are people actively detecting encrypted data?

It would be cool to experiment with these radios but have it all communicate using TLS or something.

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Let's start with all useful parts of the radio spectrum falling under various sorts of restrictions (with examples):

* Closed licensed users: cell providers, public safety, etc

* Location limits: immobile antennas like broadcast FM

* Technical limits: ISM devices, Wifi, or FRS walkie talkies

* Content limits: Amateur radio

Amateur Radio gets to bypass a ton of these restrictions:

* Anyone who can pass a test can get a license to use these frequencies

* You can transmit from nearly anywhere

* You can use tremendous amounts of power (1500W vs Wifi's piddly 0.5W or less)

* You can use whatever equipment you can solder together, no certifications other than an honor system of "I'm fairly confident it's within spec"

Encryption would negate the ability to police the few limits left but also notably, the content. And that primarily means preserving noncommercial purposes but additionally, you're required to periodically identify yourself using your FCC callsign.

The Amateur Radio community is already a little nervous with the influx of cheap $30 radios falling into the hands of unlicensed and inexperienced users (notably "prepper" types that read disaster readiness articles like this one).

> * You can use tremendous amounts of power (1500W vs Wifi's piddly 0.5W or less)

Here's a fun one: wifi 802.11b channel 1 is in an amateur band, so if you have an amateur license, you identify with your callsign (using the ESSID works), and you transmit everything in the clear, you can use modified/amplified wifi equipment at higher power levels than wifi normally allows. (The standard common-sense restriction of "no more power than needed for the application" applies.)

An amateur rocketry group I worked with (http://psas.pdx.edu/) uses this to receive wifi at 1W from a rocket miles away (and going Mach 1.1).

That is awesome. Learn something new every day.

Wow, that's really impressive. I'd have assumed you'd run into some kind of doppler shift issues going that speed unless you were pretty far away from the launch site. Why bother with a TCP/IP link, though? Seems like a less verbose protocol would be a better choice to use to get a simple data stream from your rocket to ground control.

> I'd have assumed you'd run into some kind of doppler shift issues going that speed unless you were pretty far away from the launch site.

Doppler shift might come into play if the rocket went much faster, but Mach 1 just isn't that fast compared to the speed of light. A quick calculation suggests that a 2.4GHz signal would get shifted by ~3kHz. Wifi isn't that sensitive.

> Why bother with a TCP/IP link, though? Seems like a less verbose protocol would be a better choice to use to get a simple data stream from your rocket to ground control.

We used UDP/IP for telemetry data (and had almost no packet loss). TCP/IP did allow us to SSH to the (Linux-powered) rocket for debugging, though.

I stand corrected.

Also, being able to SSH into a rocket is pretty fucking awesome on it's own. :)

Commercial use is a big one. Spectrum is extremely valuable and companies would grab it in a heartbeat. If you allow encryption, you have no way of telling whether a given user is operating commercial traffic - could be a ham, could be a taxi service running their dispatches in amateur spectrum.

For a preview of what this would look like, consider the push to run cellular service in the wifi bands (LTE-U). Wifi/Bluetooth/Zigbee devices are about to get crapped on, if Verizon gets their way.

The vast majority of governments all over the world allow ham radio, and don't consider it a threat. (Every country except Yemen and North Korea allows it.) You can obtain a license, operate radios, and talk to people all over the world. Standards between countries align quite well, so that many of the same frequencies work across most jurisdictions. It's a model of international cooperation.

A large part of that comes because nobody can hide anything on amateur radio. You can't encrypt, you can't use ciphers or codes, you can't do anything to obscure your message.

If amateur radio allowed encryption, it wouldn't have the universal international acceptance that it does today.

>you can't use ciphers or codes

That can be distinguished as such, anyway. "Yes, Oleg. The hops are coming along nicely".

Yes, it's an important point. The charming case of Velvalee Dickinson https://en.wikipedia.org/wiki/Velvalee_Dickinson comes to mind.

Encryption over airwaves sounds like pseudorandom noise / interference (ever get a scrambled channel on cable?)

If they allow encryption, they can't enforce the ban on commercial communications. Hence they mandate broadcasting in the clear.

Ah I see, thank you.

In that case, it would be interesting to use steganography to bypass those restrictions.

In the UK licence at least, the reason for mandating openness is to allow anyone to learn. Defeating the requirement seems counterproductive in that light.

It's a public space meant for public communications.

Encryption isn't really banned. You can still speak in code. It's just that automated encryption fills airways with private noise.

> Encryption isn't really banned. You can still speak in code.

No, you can't. Other than one very narrow exception, you cannot use "codes or ciphers that hide the meaning of a message". (The exception is for transmitting control commands to a radio-controlled craft or space station.)

Seriously? There are restrictions against, say, sending a stream of packets with PGP encrypted payloads? Why? I mean, what could you do over amateur radio with encrypted comms that you couldn't do over the Internet?

And how do hams share information that should be private, like a bitcoin wallet's private key? How do you shell in to the admin interface of a remote tower? You just don't, over amateur radio?

The regulations in question all talk about not "obscuring the meaning of a message", so protocols that use authentication without encryption are typically considered acceptable.

Other than that: right, you just don't. Hams share information that should be private via other communication mechanisms; amateur radio is public.

That's correct. The bands are for public use, commercial use is forbidden. The only way to effectively enforce that is to prohibit encrypted communications. Using amateur radio bands to send sensitive data is a huge mistake, that's what something like the Internet would be much better suited for.

Note that encryption is banned, but digital signatures are not. In theory you could configure SSH to authenticate but not encrypt a connection.

Administering an expensive, high power piece of hardware in the clear, with a "perfect" authentication and authorisation scheme, would require balls of steel. Someone should try it, maybe write a book about it. For science.

For PGP encrypted, yup, it's not allowed. PGP plaintext signatures are presumably allowed as they do not obscuring the meaning of the communication. That was my thesis in 2004 and I believe it to still be true based on Part 97.

Maybe in the US. Plenty of users in Canada speak in code, particularly in the north.

IIRC, if you provide the full keys required for decryption alongside the message, you can send encrypted messages.

You can speak Navajo though or other language...? Some communities also use heavy jargon such that unless being part of it, it is hard to really understand what is going on.

I wrote an extensive piece on this as part of a presentation in 2004, called Authentication Without Encryption for Ham Radio - https://rietta.com/blog/2009/08/17/authentication-without-en....

Gave examples of using PGP cleartext signatures and Cram-MD5 (shudder) challenge-response for authentication without obscuring the meaning of the communication. At the time I thought that IPSEC with Authentication, but Encryption may be the best thing, but that has been slow to take off altogether.

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