When data is encrypted, only computers with the right decoder will be able to read it. VPNs encrypt your online communications, which makes them more secure and greatly reduces the risk posed by hackers, third parties, and government actors. Encryption keys tell the computer which computations to perform on a set of data to encrypt or decrypt it. Symmetric-key encryption, or public-key encryption, is the most common form of encryption.
In symmetric-key encryption all computers use the same key to encrypt and decrypt a message.
Public-key encryption gives each computer a public-private key pair. One computer uses the public key for decryption, while the other uses the private key for encryption.
VPNs encrypt the data entering the tunnel between the user and the server and decrypt it once it reaches the other end. VPNs use encryption protocols instead of a set of keys.
Site-to-site VPNs use GRE (generic routing encapsulation) encryption or Internet protocol security protocol (IPSec). GRE is crucial for providing the framework for how to package and transport the passenger protocol, which must be transported across the internet protocol.