Joe must send Ann a message and provide Ann with assurance that he was the actual sender.
Which of the following will Joe need to use to BEST accomplish the objective?

A.
A pre-shared private key

B.
His private key

C.
Ann’s public key

D.
His public key

Explanation:
To achieve both authentication and confidentiality, Joe should include Ann’s name in the
message, sign it using his private key, and then encrypt both the message and the signature using
Ann’s public key.