[opheliate]

The author definitely should have clarified this. The standard is to use ECC for key exchange only. This can be done entirely offline - each party chooses a random secret scalar, and multiplies the base point of the curve by that scalar to produce a public point. You publish your public point in advance of communication. When you want to send a message, you multiply the other party’s public point by your secret scalar to obtain a shared key. Then, just use a well-studied symmetric AEAD construction to encrypt messages.

Of course, this doesn’t incorporate any forward secrecy, which is a key benefit of using something like TLS or Noise rather than rolling your own custom protocol.