iCal Can't Verify The Identity Of The Server
So there's an incredibly annoying error message that pops up when you try to connect iCal to a CalDAV account. It goes like this:
iCal can't verify the identity of the server "example.com". The certificate for this server was signed by an unknown certifying authority. You might be connecting to a server that is pretending to to be "example.com" which could put your confidential information at risk. Would you like to connect to the server anyway?"
This is one of those Windows-type errors, whereby you painstakingly take the effort to connect to a CalDAV account, carefully put in all your credentials, and connect to the server, and it asks you if you really want to do what you're doing. Uhh, hello—of course I want to connect... why do you think I put all this effort into connecting? Classic. Completely illogical—there's no possible way you accidentally type all your information in. It's clearly a deliberate attempt to do something legitimate.
Here's the fix:
- Click on "Show Certificate"
- Click "Always trust 'example.com' when connecting to 'example.com'"
- There are three drop-down menus: 1) "When using this certificate," 2) "Secure Sockets Layer (SSL)", and 3) "X.509 Basic Policy." Set all of these to "Always Trust."
- Click "Continue"
The next screen you'll see asks you to verify that you have permission to make these changes, as seen below:

That's it! You're done. Your iCal will never ask for those settings again. Problem solved.