Which of the following protocols provides authentication for client/server application using secret-key cryptography?

The correct answer is the protocol that provides authentication for client/server applications using secret-key cryptography, which is Kerberos. Kerberos is specifically designed to provide secure authentication through the use of symmetric key cryptography. It employs tickets that contain encrypted information used to verify user credentials without sending passwords over the network, thereby ensuring that sensitive authentication data remains secure.

Kerberos works by having a trusted authentication server that issues tickets to clients and services involved in a communication session. These tickets are then used to authenticate users to various services without the need for repeated username and password entry, which enhances security.

The other options, while related to authentication, do not focus on secret-key cryptography in the same manner as Kerberos. For instance, the Challenge Handshake Authentication Protocol employs a different mechanism for authentication involving challenges and responses which may not exclusively utilize secret keys. Internet Key Exchange primarily focuses on the negotiation of cryptographic keys rather than authentication itself. Secure Remote Password is an authentication protocol that allows password-based authentication but does not implement the same comprehensive ticketing mechanism or secret-key approach that characterizes Kerberos.

In summary, Kerberos stands out because of its dedicated structure for secure client/server authentication through the effective use of secret-key cryptography and ticket management,