[jimktrains2]

> There is no connection or session establishment between peers.

OK, so I'm not understanding why isn't a 1-to-1 message, nor why DTLS isn't an option here.

> I guess it depends on your definition of roll your own. We didn't invent AES-GCM or implement it. We are using the implementation shipped with the Golang stdlib.

You need to read better. I didn't say "crypto primitives", I've said "crypto _system_". That includes everything, including primitives, key management, authentication, replay (which means your application protocol is now part of the crypto system, not a good sign), field concatenation for singing/hashing, &c.

The most important thing is that when your improvised system fails, you will more-than-likely never know and it'll never cause any errors.