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 😉)
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.