Final answer:
Confidentiality in IPsec is achieved through the Encapsulating Security Payload (ESP) protocol, which encrypts data to protect it from unauthorized access. ISAKMP aids in the secure exchange of keys for ESP but does not provide confidentiality itself.
Step-by-step explanation:
Confidentiality in IPsec is primarily achieved through the Encapsulating Security Payload (ESP) protocol. ESP provides a means of encrypting data to ensure that it can only be read by the intended recipient. Encryption transforms the original data (plaintext) into an unreadable format (ciphertext) using a cryptographic algorithm and an encryption key. This process ensures that even if the data is intercepted, it cannot be understood without the appropriate key to decrypt it.
Internet Security Association and Key Management Protocol (ISAKMP) is used to establish, negotiate, modify and delete the security associations. While ISAKMP itself does not provide confidentiality, it facilitates the secure exchange of keys, which are essential for ESP to encrypt the data. The other options mentioned, such as AuthX and AHA, are not standard terms or protocols associated with IPsec.