Public Key Infrastructure uses asymmetric and symmetric encryption in combination. These are cryptography algorithms. Symmetrical encryption is when a message that gets typed in plain text goes through mathematical permutations to become encrypted. It protects a single private key that is generated upon the initial exchange and the key must be passed to encrypt and decrypt the information. Asymmetric encryption, also known as public key cryptography, is different as it uses two cryptographic keys — a public and a private one. The public key encrypts and the private key decrypts. Learn more about encryption keys.