There is an authentication process which takes place, when you use digital certificates to transfer secure information over the internet. The type of authentication used, depends on the information contained in the digital certificate. Your digital certificate could contain either a public key or a private key, but never both. Once you transmit the information, the root certificate uses the public or private key to perform authentication processes. As long as the information passes authentication, it is securely transmitted.
A Root Certificate Compares Public and Private Keys to Make Sure They Match
A root certificate is automatically created every time a new digital certificate is created. This certificate contains the algorithms needed to perform authentication using the public or private key. These complex algorithms, must match, even though they are encoded differently for each key. For instance, when you send encrypted information using a public key, the private key is used to decrypt the information, once it passes authentication.