So… I found out a way to send encrypted messages using amateur radio.
There is an app called Rattlegram that lets you convert a string of text into soundwaves that plays though your phone’s speaker. If I just use an app like Secure Space Encryptor (SSE) to encrypt a text, then copy-paste it to the Rattlegram app, then transmit that over radio, then using the same app to record the sound and reverse the process on the other end. Voila! Encrypted long(ish) range communications without a centralized server!
But I looked it up and apparantly its illegal to encrypt communications over the amateur radio bands. What are the odds of actually getting in trouble? 🤔
(To the FCC agents reading this: this is just a hypothetical, a thought experiment, I’m totally not gonna do this 😉)
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Its absolutely not illegal to send encrypted messages over 802.11 radio. I’m doing it now with this message.
The problem is not in the enctyption, nor the message - it’s in the unregistered broadcast in itself. It can interfere with some stuff and generally can be suspicious, thats why all amateur radio must be properly registered (the damage can be even bigger if you don’t know what your doing, so it is required to pass a test where I live to register an amateur radio).
So you can brodcast anything you want, but if it’s unregistered, be prepared for consequences
For those who are unfamiliar, encrypted or not radio signals can still be tracked down. Normal communication is like everyone in a room speaking English and we all understand each other. Encrypted communication is like speaking in gibberish that only a few can understand. BUT everyone in the room can still hear that a person is saying something.
Triangulation is a thing. If you become a pest licenced operators (see radio fox hunting) and maybe the FCC themselves will be able to direction find you easily if you aren’t careful. $7-10k is the base rate for fines for this stuff if it came to that. If you fuck around near aviation, police, fire, or other similarly important radio frequencies you will find out VERY quickly.
fun fact lora bands (the ones meshtastic uses) are mostly outside of amateur bands and have encryption enabled by default. They don’t transmit very far on their own though, they need other meshtastic devices to relay messages over longer distances. Business band licences allow encrypted radios too.
Maybe if you are in a rural area you can try it with basic FRS/GMRS walkie talkies where there isn’t a licencing requirement and by extension maybe a bit more leniance if you claimed you didn’t know it was against the rules.
I’d listen to this gentleman right here. He said a bunch of shit I don’t understand
He’s just Some Amateur.
Oh, go bite your bike. ;p
Hell, Kevin Mitnick was caught via cellular tower triangulation all the way back in the 90’s.
It’s far from new technology too, so at this point you would think radio triangulation would be piss easy and cheap to do.
Agreed on the LoRa devices. I personally think the future of comms is in meshed low power high latency devices.
https://hackaday.com/2022/05/25/long-distance-text-communication-with-lora/
https://github.com/BigCorvus/LORA-QWERTY-Communicator
These take some knowledge to build, but I think they’re pretty slick.
Yep, Usually people dont care until you start blasting away legit services. Then a lot of people start showing up at your door. Theres triangulation devices on https://www.tindie.com/ for amateurs that are very cheap and the pros have MUCH better equipment.
Meshtastic ( !meshtastic@mander.xyz ) is in a small range/spectrum and consolidated in LoRa. Its very unlikely to cause issues so its tolerated. Its very much a legal way to get text to a friend or community…if your local community is big enough.
FRS and GMRS have similar restrictions on encoding, and also limits or prohibitions on digital/data modes.
Ignorance of the law is not an excuse, but compliance with the letter while violating the “spirit” is generally acceptable.
What if instead you hid an encrypted signal within an otherwise perfectly legible audio signal? Imagine a song being played. To the ear the song seems perfectly normal. But, unbeknownst to a casual listener, there is an encrypted signal embedded within the audio signal. For example, data could be embedded within a song by ever-so-slightly raising or lowering the pitch of a song multiple times per second. Then if you had a copy of the original file, software could compare the original file to the song transmitted over the radio. The locations where the pitch rose or fell could be noted, and the data could be retrieved. You could send encrypted data without anyone realizing you’re sending encrypted data. To anyone else listening, it would simply sound like a song or other audio track being played.
Actually, this idea has some merit, because it already has examples in other mediums. It’s technically referred to as “steganography.”
A common example with computers is hiding text, files, or applications within an image file.
https://github.com/7thSamurai/steganography
In the example for how to use this simple Image Steganography tool, the user hides a ZIP files with the entire contents of the book Dr. Jekyll & Mr. Hyde into the example image.
I don’t see why something similar couldn’t be achieved with audio.
In fact, here’s an article on some basic audio steganography methods.
Not an expert, but I’m not sure steganography would be compatible with analog lossy data transmission methods like ham radio. The examples you linked relate to digital lossless audio, where it’s easy to hide the data in individual bits.
There’s a whole bunch of different steganographic methods. You wouldn’t necessarily have to apply them to audio signals, you could apply them to the text itself. It’s certainly trickier, so you would want to keep the plain text very short so your ciphertext doesn’t get too long or weird
Sounds more like you’re using codewords and phrases at that point? Or do you mean something different?
I’m not clever enough to come up with a good example on the spot, but you could have something along the lines of a scheme where the word selection corresponds to a not-obvious code. For example, if you wanted to secretly send the word “hello”, and you’ve previously given your receiver a code word “apple”:
Hello > 7 4 11 11 14 Apple > 0 15 15 11 4
Adding the code word to the secret message, you’d get:
7 19 0 22 18 > H T A W S
Then your message could be something like:
How are you doing? Today, I went to the store. Avocados were on sale. When do you want to meet up? Saturday looks good for me.
There are definitely way better methods to do the encoding part, and probably also better ways of doing the concealment part.
Yeah. At that point I think it’s no longer considered steganography. It’s really interesting though all the stuff they did during the cold war to get past surveillance.
Its not too hard to set up most modern trancievers for digital modes, I think the harder part would be making the mode itself.
It’s fine, but you need to have an error correction layer.
Digital-over-analog methods like QR codes or modems are some examples.
I mean, it’s certainly possible. But given that you’re trying to keep the audio as legible speech, the bandwidth would probably be horrendous.
Yeah for sure! I’d be happy to encode a single word in a minute of audio.
This was used in the war between Russia and Finland in 1941. Without software though.
Russian had placed bombs in a city in Finland and the bombs could be triggered by a combination of frequencies broadcast on radio.
The Finnish engineers figured it out and drove a car around the city broadcasting a song that would scramble the frequencies.
Question: Why is that illegal?
I’m maybe not the best person to answer but I think the general idea is that it’s supposed to be an open communication for any licensed person to use and any that anyone is allowed to listen to, and it’s supposed to be used exclusively for non-commercial purposes, and there’s some additional regulations about who can use it and how
If you’re sending encrypted transmissions, no one can tell if you’re using it appropriately or not. You may be transmitting on frequencies your license doesn’t give you permissions to use, you may be using it for commercial purposes, you may not be identifying properly, etc.
Radio frequencies are a somewhat limited resource. There’s only so many frequencies allocated to amateur use or to different commercial uses, etc. If someone’s using amateur frequencies in a way they shouldn’t, they’re tying up those parts of the spectrum so that properly licensed users can’t use them for the purposes they’re reserved for
And if they’re encrypted you can’t really differentiate the lawful from the unlawful users making it harder to police.
Idk, probably some Cold War “Anti-Espionage” stuff they just left on the books.
The common reason I hear from reddit is it supposedly stops commercial use of ham frequencies
Wait so if u send encrypted messages over Meshtastic is that illegal?
If your Meshtastic device is transmitting in the ham bands (some do) encryption is illegal. Most people use Meshtastic outside the ham bands though.
I don’t know if it’s illegal, but Meshtastic takes place outside the amateur radio bands (using LoRa IIRC) and thus isn’t bound by amateur radio licensing requirements, so the law prohibiting encryption on the ham bands doesn’t apply. Some other law might.
TLDR: just use your phone. Yes people causing interference through improper use of the ham bands do get run down by the FCC some of the time. If you do it at low power on some UHF frequency with very few users, probably no one would notice if you didn’t do it too often, but those frequencies are only good for short range communication anyway, so you might as well use your phone. The low frequencies that can travel international distances are more interesting but they are also more closely observed.
If you are ok with short range you can also use LoRA or meshtastic instead of ham bands. Encryption is perfectly fine there.
I don’t know how easy it would be to catch, suppose that depends on the range. That being said, I would not fuck with the FCC.
It does depend on what band you transmit on. If you transmitted a two second burst, once, on 23cm, and never did it again? You’re almost certainly going to get off scot free. Try that on the HF bands, or even on 2 meters where a lot of people are listening, transmit for longer and do it regularly? We WILL find you.
Encryption does not hide the presence of a message. Transmitting with a radio is literally the act of shining a light into the sky. That light is redder than the reddest infrared so we can’t see it, but it’s light nonetheless. We transmit meaning using that light by blinking it on and off, or varying either its brightness or color in ways that mean something to each other. Encrypting just means the scheme you use to vary the brightness or color doesn’t mean anything to the general public, only the person you’re trying to talk to. Everyone else sees meaningless noise. But, they still see it.
You can tell which direction a radio signal is coming from, using a directional antenna like a yagi, you literally sweep the antenna around and listen for where the signal is strongest. It’ll literally point to the transmitter. Do this from at least two locations and you can draw a line on a map that crosses pretty close to where the signal is coming from. Hams do this for fun, it’s called fox hunting.
On a related note, numbers stations do exactly this. If you listen to the HF bands, you may hear voices reading strings of numbers or letters in some foreign language. At least one of these has been confirmed to be a one-way communication system for governments to talk to their spies in the field. The messages are encrypted with a one-time pad system which is not breakable unless you have the one-time pad, the message which might sound like “three, three, seven, three, nine. Three, three, seven, three, nine. Eight, four, six, three, two. Eight, four, six, three, two.” is meaningless to most, but it’s trivial to detect where it comes from.
Look up the account of the Yosemite Sam station, some hams started hearing the voice of Looney Tunes character Yosemite Sam saying “Varmint! I’ma gonna bloooow ya ta smithereenies!” from the cartoon Bunker Hill Bunny, followed by a digital data burst. This would happen on several frequencies at regular times. So they tracked it down, ended up at an R&D facility with a bunch of antenna masts out back and were quickly met by employees telling them to stop taking pictures.
Even if you aren’t bothering anyone, hams will foxhunt you because it’s a fun mystery to solve. If you are bothering anyone, hams will foxhunt you to turn you over to the FCCs punishment division.
I wouldn’t mess with the federal government personally
The restriction is against encoding for purposes of obscuring meaning. You can use encryption for things like authentication or controlling remote equipment.
“Rattlegram” seems to be similar to the AFSK systems used for Packet Radio, APRS, etc. You might look into those methods before implementing your own.
Assuming Rattlegram encoding can fit within the audio bandwidth (which might not be the case on the narrower, longer-range ham bands) you should be able to use Rattlegram to send ordinary text messages. However, you would be allowed to use SSE to send authentication and control messages.
You could only use this approach on frequencies allocated for digital modes.
A guy just got a 35k fine two weeks ago.
It would probably be better to do it on a frequency nobody cares about like CB or 433.
