Which of the following is NOT an asymmetric key algorithm?

A.
RSA

B.
Elliptic Curve Cryptosystem (ECC)

C.
El Gamal

D.
Data Encryption Standard (DES)

Explanation:
Data Encryption Standard (DES) is not an asymmetric key algorithm; it’s a symmetric key algorithm.
DES is a symmetric block encryption algorithm. When 64-bit blocks of plaintext go in, 64-bit blocks of ciphertext
come out. It is also a symmetric algorithm, meaning the same key is used for encryption and decryption. It uses
a 64-bit key: 56 bits make up the true key, and 8 bits are used for parity. When the DES algorithm is applied to
data, it divides the message into blocks and operates on them one at a time. The blocks are put through 16
rounds of transposition and substitution functions. The order and type of transposition and substitution functions
depend on the value of the key used with the algorithm. The result is 64-bit blocks of ciphertext.
Incorrect Answers:
A: RSA is an asymmetric key algorithm.
B: Elliptic Curve Cryptosystem (ECC) is an asymmetric key algorithm.
C: El Gamal is an asymmetric key algorithm.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, p. 801