Which protocol in IPSec provides encryption and limited authentication?

The protocol that provides encryption and limited authentication within the IPSec framework is the Encapsulating Security Protocol (ESP). ESP is designed to ensure the confidentiality of data as it transmits over a network by providing encryption for the payload of the packet. Furthermore, it incorporates mechanisms for integrity and limited authentication, typically through a cryptographic hash function, which helps verify that the data has not been altered during transmission and can also authenticate the sender, albeit to a limited extent compared to other protocols designed specifically for authentication.

In contrast, the Authentication Header (AH) protocol focuses exclusively on authentication and integrity but does not provide encryption. Therefore, it cannot ensure the confidentiality of the data being transmitted. Secure Sockets Layer (SSL) is a separate protocol used to secure communications over a computer network but is not part of the IPSec suite. Lastly, the Internet Control Message Protocol (ICMP) primarily handles network-related error messages and operational queries, lacking any encryption or authentication functionalities altogether.

Therefore, ESP uniquely satisfies the need for both encryption and limited authentication in the context of IPSec.