Re: [Endymail] spam versus cleartext

["John R Levine" <[e-mail]>]

>I've been wondering about this. When I think about using crypto (whether 
>encryption or signatures), it seems like requiring a discovery mechanism 
>was increasing the burden. For many of my correspondents, with whom I'm 
>currently communicating in the clear, a TOFU key exchange in those 
>emails (authenticated out-of-band) might be a plausible mechanism.

Take current implementations of S/MIME and adjust them to allow
self-signed certificates in addition to (or instead of) ones signed by
a list of CAs configured into the MUA.

All done.

In my experience, the main problems with S/MIME are key distribution
and key discovery.  For key distribution, you need to go to someplace
like Comodo or Startcom to get a signed cert, which goes into your
browser, and then you need to do some grotty software specific thing
to export it from the browser and import it into the MUA.

For key discovery, in practice everyone populates their keystores with
certs from incoming signed mail, which is supposed to be safe because
it only accepts keys that are signed.  It is supposed to be possible
to get keys via LDAP from a key server, but people don't do that.

A system with key discovery, so you can send all mail encrypted to
someone, including the first one, seems more useful than one that
requires an insecure handshake first.  Key distribtion via DANE could
be a reasonable approach.

R's,
John