> 1) The wiki says don't use ADH, presumably because ADH provides > encryption but not authentication and is exposed to man in the middle > attacks. Is that the only reason? Use ECDH, it's less expensive computationally. > 2) Are the same encryption keys used every time with ADH? Yes. That's the other BIG reason :) You really want ephemeral, and therefore ECDH > 3) Is it possible to use ephemeral DH without using certificates? I was not > able to get that to work. Yes. This is "null" auth. > 4) What is the best practice for establishing an anonymous encrypted > channel using OpenSSL? Postfix does this kind of thing, as does other SMTP software. Look around for 'opportunistic encryption' perhaps.
