Hadmut Danisch wrote:
Keep the road warriors in mind. People keep critizing my RMX proposalActually, we can -- my original proposal at <http://www.chaoszone.org/misc/spam.html> proposed using digital-signature based non-repudiable relays *in addition to* what I called DNSMX (==RMX) lookups: the RMX technique solves the problem for the vast majority of considerate SMTP servers, while road warriors (of whom I have to count myself as one -- this mail is reaching you via a SMTP server on my laptop) could use the digital signature based approach. Either way, relays are unambiguously identified.
because they want to be able to send e-mail from virtually anywhere
with their mobile computers. You can't address this problem with a relay-identity-only CA.
It's actually just a different implementation of the RMX approach to reduce the mail origins to a limited number of authorized relays. It's just a different authentication/authorization mechanism.
Indeed. The two complement each other quite well, I feel.
In my original proposal, to *send* email, there is *no cryptography* involved -- you only need a static string that can be generated by a CA for you (or you can generate it yourself).The second problem is that you will never get such a CA approach sufficiently widely spread. What to do with countries which don't allow cryptography? What to do with admins who don't understand cryptography?
What to do with stolen or lost key? You'll need a revocation infrastructure, usually based on web or ldap servers.Stolen/Lost/Compromised Keys can be revoked. Revocation checking can be done as part of the standard key verification process. Key revocation is possible in both RFC 2440 as well as X.509, so it is more of an infrastructure issue. The revocation infrastructure could possibly be managed by an entity like spamhaus or any responsible entity, perhaps with an IETF charter and mandate.