Se(cure) Conn(ection)

seconn is a simple golang library that provides an encrypted connection over a net.Conn.

It uses curve25519 to establish a shared key between the 2 parties and then uses AES encryption to pass the data back and forth.

How do a do any kind of authentication to prevent a MITM attack?

Check out the auth package. It uses the GetMessage/SendMessage API to perform a signed token exchange and verifies that the server side is using the agreed upon key.