Which of the following are restricted to 64-bit block sizes? (Choose two.)

A.
PGP

B.
DES

C.
AES256

D.
RSA

E.
3DES

F.
AES

Explanation:
B: The Data Encryption Standard (DES) has been used since the mid-1970s. It was the primary standard used
in government and industry until it was replaced by AES. It’s based on a 56-bit key and has several modes that
offer security and integrity. It is now considered insecure because of the small key size.
E: Triple-DES (3DES) is a technological upgrade of DES. 3DES is still used, even though AES is the preferred
choice for government applications. 3DES is considerably harder to break than many other systems, and it’s
more secure than DES. It increases the key length to 168 bits (using three 56-bit DES keys).