Re: a few short notes

On 2-feb-04, at 0:47, Jari Arkko wrote:

> I think the hard question is what level of "authentication" to require.
> I am pretty sure 99.99% of users want better protection against spoofed
> addresses than we currently have. But I am not sure they are willing to
> go as far as mandating a global PKI of all e-mail users. So what's 
> left, then?

Per-user strong authentication already exists in PGP and S/MIME. No 
need to reinvent the wheel, especially as it seems most people seem to 
be able to live without this feature today.

Another approach would be to authenticate servers, and trust servers to 
authenticate their users. Since there are orders of magnitude less 
servers than users, and unlike users, servers are typically reachable 
24/7, this makes the whole key distribution problem much easier to 
handle. Anyone feel it is unreasonable to force people who want to run 
their own server to get a certificate for it? (Assuming a selection of 
roots, no verisign lock in of course.)

A third approach would be return routability. This is a simple 
verification procedure that's implied in protocols like TCP and 
explicitly used in protocols such as mobility for IPv6. This could work 
as follows: when X has a message for Y, X contacts Y and says "I have a 
message for you from a@x with message id 23, come get it when you're 
ready" and then Y gets to think about this for a while and finally 
initiate a session towards X and request the message.