CompTIA Security+ Question E-80

Peter must send Ann a message and provide Ann with assurance that he was the actual sender. Which of the following will Peter 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

Answer: B

To achieve both authentication and confidentiality, Peter 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.