When using key agreement, what is the purpose of encipher only?

• A. To only negotiate public key exchanges
• B. To hide actual data being transmitted
• C. To encipher data in conjunction with a key agreement
• D. To confirm certificate authenticity

Answer: (C)

Encipher only in the context of key agreement serves the purpose of enciphering data using the agreed-upon key generated during the key exchange process. The essence of key agreement protocols is to securely establish a shared key between parties, and once this key is agreed upon, it can be used to encrypt (encipher) data, protecting the contents of the communication from eavesdroppers.

This process is crucial in ensuring that even if the transmitted data is intercepted, it cannot be deciphered without the key that both parties have established through the key agreement. The correct understanding of this relationship reinforces the importance of combining key agreement with encipherment to maintain confidentiality and security in communications between the parties involved.

In this scenario, while some of the other choices touch upon different aspects of encryption or secure communications, they do not specifically address the function of enciphering data as part of the key agreement process, which clearly outlines the correct purpose of encipher only.