It is the most common VPN protocol, and VPNs use it to facilitate the safety of data on IP networks including the internet.
Another tunneling protocol that VPNs use to secure data moving from one point to another.
Asymmetric key encryption is one that use a public key to encrypt and a private key to decrypt—essentially, two different keys for the encryption process.
SHA is equally strong and secure, and most VPNs use it to encrypt and decrypt data that is traveling through a VPN tunnel.