[geoffhill]

I like this idea a lot!

A less powerful solution implemented completely locally: A "known_hosts" file for SSL certificates for repeat visits. As long as you've visited a site once before, any subsequent visits will be safe.

To deal with certificate upgrades, certificate Y could present a signed verification that it obsoletes a past certificate X. Then, when a client that trusts certificate X receives certificate Y, it can update its "known_hosts" file accordingly. This change would require more than just local changes, but remote cooperation.

[nwh]

> As long as you've visited a site once before, any subsequent visits will be safe.

As long as your first visit wasn't compromised.

Sites like Google's also don't use the same certificate every time. Out of my own curiosity I scraped their SSL sites for a while, I saw tens, maybe hundreds of different certificates being presented. There's no way of telling which are actually Google's.

[gwu78]

Certificates could be initially delivered out of band, e.g., in person, or by postal mail. Perhaps in a printed format that can be scanned in.

But then there's no way of telling which postal mail is actually from Google, right? :)

[nwh]

We'll sign the out of band letters with their signing key to prove it's aut- wait. Chicken and egg problem.

[gwu78]

Or we could just sign the OOB letters, on company letterhead, with an ink pen.