[joppy]

This is right - asymmetric crypto is awesome but just not anywhere near as fast as something like AES for chewing through chunks of data. So some anonymous asymmetric crypto (Diffie-Hellman or similar) is used to set up an encrypted channel, i.e set up a shared AES key, and then RSA is used to verify that the entity on the other end actually holds the private key for that subdomain. After that it’s AES pretty much all the way.