I believe pretty much any outside of the amateur bands that you're able to get appropriately licensed for. I know the commercial "business band" can be encrypte

I believe pretty much any outside of the amateur bands that you're able to get appropriately licensed for. I know the commercial "business band" can be encrypted, ISM low-power bands can be encrypted (i.e. the same band WiFi and Bluetooth uses at 2.4GHz), and obviously cell phone transmissions are. I'm providing this link not as an endorsement, but as an example of encrypted business band radio: https://midlandusa.com/business-two-way-radios-secure-communication/ https://midlandusa.com/business-two-way-radios-secure-commun...