Chapter 3 Authentication for FortiOS 5.0 : Certificate-based authentication : Certificates overview : Certificate types on the FortiGate unit : Remote certificates
  
Remote certificates
Remote certificates are public certificates without a private key. For dynamic certificate revocation, you need to use an Online Certificate Status Protocol (OCSP) server. The OCSP is configured in the CLI only. Installed Remote (OCSP) certificates are displayed in the Remote Certificates list. You can select Import to install a certificate from the management PC.