Which of the following symmetric key algorithms are examples of block ciphers? (Select THREE).

A.
RC4

B.
3DES

C.
AES

D.
MD5

E.
PGP

F.
Blowfish

Explanation:
B: Triple DES (3DES) is the common name for the Triple Data Encryption Algorithm (TDEA or
Triple DEA) symmetric-key block cipher, which applies the Data Encryption Standard (DES) cipher
algorithm three times to each data block.
C: Advanced Encryption Standard (AES) is a block cipher that has replaced DES as the current
standard, and it uses the Rijndael algorithm. It was developed by Joan Daemen and Vincent
Rijmen. AES is the current product used by U.S. governmental agencies.
F: Blowfish is an encryption system invented by a team led by Bruce Schneier that performs a 64-
bit block cipher at very fast speeds.