When SSL is used with Apache via the mod_ssl module, it will create an encrypted RSA file which has two components a private file which is kept secure on the server and a public file which is placed in the Certificate file and is thus used by users when they connect to the server. Users will be able to communicate securely then using the encryption that results in this kind of communication.
Read more »Ubuntu SSL 2048-bit Key
http://beginlinux.com –