Network Security, Firewalls, and VPNs, 3rd Edition

The Relationship Between Encryption and VPNs

Encryption and a secure VPN are virtually inseparable. A secure VPN exists only because the traffic is encrypted, but some trusted VPNs may or may not use encryption. To fully understand and appreciate the operations of VPNs, you need a reasonable understanding of encryption.

Encryption is just one aspect of the larger topic of cryptography. Cryptography is the art and science of changing information so it is not easily recognized or understood by unauthorized third parties. Cryptography occurs through a complementary and reversible set of processes: encryption and decryption. Encryption is the process of converting original usable data, called plaintext, into an unusable chaotic form, called