Ok here is my situation: I have 2 Macbooks (lets call them #1 and #2) and I started developing on #1 in 2010.
This June 2011, my distribution certificate expired and I had to renew it. On my #1 Macbook I was able to update the certificate into the keychain and everything was fine when updating my app again.
Now, in August 2011, I wanted to update the certificate on my #2 as well and thought I just could download it from dev.apple page and add to the keychain. But when I did that, the private key below the certificate was missing! Why is that? The private key for the distribution profile for 2010 was still there visible below the (expired) certificate.
It made me so crazy that I went back to Macbook #1 and exported both of the keys there to the #2. That worked of course, but it can’t be the solution for the future! What if the Macbook crashes and I want to do everything via new Macbook? Lets assume I couldn’t have done the export from #1, how would I get the freakin private key below the cert in #2?
Secondly, I am a bit confused: Which keys do I need to back up? I thought it was only the private key, but I couldn’t get it “below” the distribution certificate on my new Macbook #2, which scares me a little bit.
BTW: the certificate war with Apple is a big joke, but that’s another topic.
Once you setup your certificates, go to Xcode’s Organizer and under Devices tab on the left side you will see Developer Profile section where you can export your developer profile. It’s a password-protected files that will hold all your development/distribution certificates and their respective private keys, as well as any provisioning profiles you have installed. When you have this file, it’s all you need to move development to new machine, just double-click it and when Xcode opens it, enter the password.
And believe it or not, “certificate war” is not a big joke with Apple, you should see WP7, but that’s for some other place to discuss about.