Which type of encryption should be used?

A VPN (Virtual Private Network) is not a type of encryption but rather a technology that creates a secure connection over the internet. While it often employs encryption protocols for data transmission, it does not itself provide encryption; instead, it serves to encapsulate and protect data as it travels across public networks.

IPSec (Internet Protocol Security) is a suite of protocols used to secure Internet Protocol (IP) communications by authenticating and encrypting each IP packet. Although it involves encryption, IPSec is primarily used for securing network traffic rather than providing the asymmetric encryption needed for secure communications between users or devices.

Hashing is a process that transforms data into a fixed-size string of characters, which is typically used for data integrity verification rather than encryption. It does not allow for decryption, as it is a one-way function, making it unsuitable for secure data transmission where confidentiality is required.