In what type of attack does an attacker try, from several encrypted messages, to figure out the key
using the encryption process?

A.
Known-plaintext attack

B.
Ciphertext-only attack

C.
Chosen-Ciphertext attack

D.
Known Ciphertext attack

Explanation:
“Ciphertext-Only Attack
In this type of attack, the attacker has the ciphertext of several messages. Each of the messages
has been encrypted using the same encryption algorithm. The attacker’s goal is to discover the
key that was used in the encryption process. Once the attacker figures out the key, she can
decrypt all other messages encrypted with the same key.
A ciphertext-only attack is the most common because it is very easy to get ciphertext by sniffing
someone’s traffic, but it is the hardest attack to actually be successful at because the attacker has
so little information about the encryption process.” Pg 531 Shon Harris CISSP All-In-One Exam
Guide