The rest of the ideas seem valid, it's a shame to have the project undermined by the crypto.
Is there no website of canonical examples of good crypto that can be shown to the author, so that they may trivially have good crypto?
Is there no website of canonical examples of good crypto that can be shown to the author, so that they may trivially have good crypto?
Ultimately protocols like this need to be designed by someone with extensive experience in cryptography, then reviewed and tested by many similar people, before they can be considered safe to use.
Iirc this is what wireguard is based on and wireguard would be a great project to learn the crypto choices from.
The way for a non-cryptographer to make good crypto is to not write any crypto and rely on standard setups like TLS. Even chaining standard algorithms together can be dangerous.