Installing SSL certificates on Safari browsers
From Lunarpages Web Hosting Wiki
How do I install an SSL certificate on the Safari browsers on Mac OSX?
1. If you already have the certificate file, go on to step 3. If not, you will need to download the certificate file. Some websites have a Download certificate here link, and some do not. If it does not, you will need to download it manually.
2. Open a terminal window and type:
openssl s_client -showcerts -connect some.server.com:port
A commonly used port is 443. Now, once you run that command, copy the output beginning from -----BEGIN CERTIFICATE----- and including that line, up to END CERTIFICATE, including that line as well.
Now save it as a .cer file. Now you're ready to install it.
3. Press and hold CTRL button and click on the saved certificate file and open with Keychain Access.
4. Choose the X509 Anchors keychain and click on OK.
5. You will need to enter the administrator username and password to install any and all certificates. Clicking OK after entering the administrator details (when and if requested) will complete the installation.