Apologies for pointing to kind of an old article, but this article goes into depth on how Firefox 3 handles errors with SSL Certificates. These errors include such things as domain name mismatches, expired certificates, and untrusted (e.g. self-signed) roots. The comments on the article also include a lively and intelligent discussion of the issues surrounding self-signed certificates.

Mozilla Corporation member Deb Richardson gives us this thorough tour of the new trust indicators in Firefox 3. Apparently Firefox will have a five-tiered color scheme, which goes (in decreasing order of trust):

Green - EV SSL Certificate. Complete idenity known, both domain and organization.
Blue - SSL Certificate. Partial identity know. Domain only.
Gray - no information.
Yellow - invalid certificate. Deb's example includes a self-signed certificate.
Red - phishing site.

The careful observer will notice that this scheme is very similar to (though not identical to) IE7's four-tier system of green, "clear" (white), yellow, and red. The meanings of yellow and red are subtly different....

First big development. Firefox 3 in out in beta 3. And it has Extended Validation support.

Like Internet Explorer 7, Firefox 3 includes a green-colored bar at the top of the chrome that displays when accessing a site with an EV SSL Certificate. This green bar sits adjacent to the URL and contains the name of the organization and the country. There certainly are some cosmetic differences, like the fact that the organization name is to the left of the domain address in Firefox and to the right in IE7. In the grand scheme of things I don't view these differences as important.

As Firefox moves into release, you can expect me to track milestones and adoption for this browser, just as I have for IE7 and will for any other significant browser that comes out with EV support. And in case you're...

Firefox 3 beta release 2 is available, and it has support for Extended Validation SSL. As covered earier by the SSL Blog, Firefox has some other SSL improvements built in as well. I just downloaded and haven't installed it yet. I'll get it running and let you know what I see.