Introduction

There are two kinds of keys. They are symmetrical keys and asymmetrical keys.

Keys are special numbers that when used with encryption and decryption algorithms perform transformations on data.

PKI (Public Key Infrastructure) uses both symmetrical and asymmetrical keys.

Symmetrical Keys

A key that is used for both encryption and decryption is a symmetrical key. It is sometimes referred to as a secret key or a shared key.

Asymmetrical Keys

Asymmetrical keys come in pairs that are mathematically related. One is used for encryption and the other is used for decryption.

PKI

PKI uses both symmetrical and asymmetrical keys. Asymmetrical key algorithms are compute intensive and slow when compared to symmetrical key algorithms. Therefore, PKI generates a random symmetrical key to encrypt messages. It encrypt the message's symmetrical key using an asymmetrical encryption a key. This saved the overhead of encrypting large messages with an asymmetrical key.