Which of the following is NOT a service provided by Encapsulation Security Payload (ESP)?

The correct choice highlights that user authentication is not a service provided by Encapsulation Security Payload (ESP). ESP is primarily designed to ensure confidentiality, integrity, and authenticity of data packets being transmitted over a network. It does this through the encryption of the payload, ensuring that data remains confidential while in transit, as well as through methods that can verify the integrity of the data and provide data origin authentication.

Traffic flow confidentiality refers to the ability to obscure the patterns of traffic between sender and receiver, which prevents eavesdroppers from gaining insights into the nature or frequency of communications. Connectionless integrity ensures that the packets have not been altered during transit, while data origin authentication allows the receiving party to verify where the data came from. However, user authentication, which typically involves confirming the identity of a user attempting to gain access to a system or resource, is not a function of ESP. This distinction is essential in understanding the specific services that ESP provides in the context of IPsec (Internet Protocol Security).