An SSL certificate consists of a public key and a private key. The public key encrypts information, and the private key deciphers it. Private keys can be 1024 to 2048 bits long and include all printable characters. The maximum size is 16KB.

There are trusted and non-trusted certificates. A trusted certificate has no private key, only a certificate file. For each, you can add or delete a certificate. You cannot delete a certificate if it is currently assigned to a service.