Public key cryptography is an essential part of using digital certificates for increased security. This security method uses a pair of keys which are uniquely different, but must match mathematically when authenticated against one another. One set of keys is always retained by the issuer and is the private key. The other set of keys is shared with multiple users requiring access to the issuers systems or electronic data, and is the public key.
Public Key Cryptography Can Be Compared to a Door Lock and Key
The easiest way to understand how public key cryptography works, is to compare the private and public keys to an actual door lock and door key. In order to unlock the door, you need the correct type of key. For others to enter your home, when you are away, they will need the matching door key, otherwise they cannot gain entry. In this example, you can relate the door lock to the private key and the door key to the public key. These electronic keys function in a similar manner, where you need one to gain access through the other.