In a brute-force attack, what percentage of the keyspace must an attacker generally search
through until he or she finds the key that decrypts the data?

A.
Roughly 50 percent

B.
Roughly 66 percent

C.
Roughly 75 percent

D.
Roughly 10 percent

Explanation:
In a brute force attack, an attacker tries every possible key with the decryption
algorithm, knowing that eventually one of them will work. On average, a brute force attack will
succedd about 50 percent of the way through the keyspace.
Reference: Implementing Cisco IOS Network Security (IINS 640-554) Foundation Learning Guide,
By Catherine Paquet