On Fri, Nov 22, 2002 at 09:23:57PM +0100, Eugen Leitl wrote: > Question: if you control the traffic layer you can easily disrupt > opportunistic encryption (STARTTLS & Co) by killing public key exchange, > or even do a MITM.
An attacker can prevent opportunistic STARTTLS by modifying the STARTTLS tag in SMTP. > Is there any infrastructure in MTAs for public key caching, and admin > notification if things look fishy? (Fishy: a host which used to do PKI > with you suddenly says it can't, or its key differs from key you cached). ssh does this. Eric