To generate a protected disk image containing your CSR, private key, and development certificate:
1. Place your CSR, private key, and development certificate file in a newly created directory, named iPhone Developer Identity Documents.
2. Launch the Disk Utility application, located in /Applications/Utilities.
3. Choose File > New > Disk Image from Folder.
4. Choose the iPhone Developer Identity Documents directory you created earlier.
5. Select a location for the new protected disk image.
6. From the Encryption pop-up menu, choose “256-AES encryption”.
7. In the dialog that appears, enter a password for the disk image.
8. Place the protected disk image in a secure location.