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 😉)
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.
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.
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:
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.