How do I install a Digital Certificate onto Mac OS X Leopard (v10.5)?
To open Keychain Access, start by clicking on Go in the Finder menu and the select Utilities.
When the Utilities window opens up, look for and click on the icon named Keychain Access. The Keychain Access icon is displayed below:
Note: Alternatively, you can open the Keychain Access by typing "Keychain Access" in the Spotlight search field at the top.
The Keychain Access Window opens up. With the Keychain Access window open, go up to the Keychain Access menu at the top and select File and then click on Import Items.
Another window will appear. In this window, you should browse to the .p12 or .pfx certificate file on your computer. When you have highlighted it, select the Destination Keychain from the drop down list and then click on the Open button.
A new window will appear requesting for the password for the certificate to be entered. Input the password and then press OK.
When you put in the correct password, you will see that your certificate has been successfully installed along with the private key, the Intermediate Certificate and the Root Certificate.