CompTIA Security+ Question L-69

Peter, a user, wants to send an encrypted email to Ann. Which of the following will Ann need to use to verify that the email came from Peter and decrypt it? (Select TWO).

A. The CA’s public key
B. Ann’s public key
C. Peter’s private key
D. Ann’s private key
E. The CA’s private key
F. Peter’s public key

Answer: D,F

Peter wants to send a message to Ann. It’s important that this message not be altered. Peter will use the private key to create a digital signature. The message is, in effect, signed with the private key. Peter then sends the message to Ann. Ann will use the public key attached to the message to validate the digital signature. If the values match, Ann knows the message is authentic and came from Peter. Ann will use a key provided by Peter—the public key—to decrypt the message. Most digital signature implementations also use a hash to verify that the message has not been altered, intentionally or accidently, in transit. Thus Ann would compare the signature area referred to as a message in the message with the calculated value digest (her private key in this case). If the values match, the message hasn’t been tampered with and the originator is verified as the person they claim to be.