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 😉)
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.
https://en.wikipedia.org/wiki/Säkkijärven_polkka