Which of the following is a true weakness of DES?

A.
S-box usage

B.
Secrecy of algorithm

C.
Incompatible with AES

D.
Key size

Explanation:
Today a 56-bit key can only provide a few hours worth of protection.
If DES had a larger key size, then it could provide more protection. Because of this
weakness AES was developed, which uses the Rijndael algorithm. AES replaces DES and
Rijndael has much larger key sizes than DES.