Steve (Crocker),
I will grant that my original proposal was somewhat lacking, and that
making the mail provider a CA is not worth it from the standpoint of
the administrative overhead required to deter rogue actions.
However, consider the following straightforward protocol, or something
similar it:
1. user obtains base certificate normally from her standard CA,
2. user signs address cert request and sends to mail provider,
3. mail provider countersigns and sends to user CA, perhaps via user,
4. user CA sends user an encrypted message to user at that mail
address, containing some unique information, eg, a confirm code,
5. user decrypts and reads mail, sends confirm reply back to her CA,
6. CA then issues the requested address certificate.
Once the address certificate had been issued, either the user or the
provider would have the right to request that it be revoked at any time.
There are good business reasons for address certificates, so I plan to
continue working on this.
/ Frank