Which protocol is responsible for securing communication with encryption in IPsec?

The Encapsulating Security Payload (ESP) is the protocol responsible for securing communication with encryption in IPsec. ESP provides confidentiality, integrity, and authentication for the data being transmitted over an IP network. By encrypting the payload, ESP ensures that unauthorized users cannot read the data as it traverses through potentially insecure mediums. This makes ESP a critical component in establishing secure virtual private networks (VPNs) and protecting sensitive information in transit.

In the context of IPsec, while the Authentication Header (AH) provides integrity and authentication, it does not offer encryption. Therefore, ESP stands out as the protocol that ensures the actual content of the communication is secured through encryption. Additionally, the Internet Key Exchange (IKE) protocol is primarily used for establishing and managing the keys necessary to facilitate encryption but does not perform encryption itself. Generic Routing Encapsulation (GRE) is used for tunneling data but does not provide any security features, making it unrelated to the encryption aspect that ESP covers.