Cryptography Multiple Choice Questions on “HMAC, DAA and CMAC”.
1. Cryptographic hash functions execute faster in software than block ciphers.
a) Statement is correct
b) Statement is incorrect
c) Depends on the hash function
d) Depends on the processor
Answer: d
Clarification: The execution time varies from processor to processor for different cryptographic systems.
2. What is the value of ipad in the HMAC structure?
a) 00111110
b) 00110010
c) 10110110
d) 01110110
Answer: b
Clarification: ipad is 36 in hexadecimal.
3. What is the value of opad in the HMAC structure?
a) 00111110
b) 00110010
c) 10110110
d) 01011100
Answer: d
Clarification: opad is 5C in hexadecimal.
4. Data Authentication Algorithm (DAA) is based on
a) DES
b) AES
c) MD-5
d) SHA-1
Answer: a
Clarification: The DAA is an algorithm based on the DES cipher block chaining mode.
5. Which mode of operation is used in the DAA?
a) output feedback mode
b) electronic code block mode
c) cipher block chaining mode
d) cipher feedback mode
Answer: c
Clarification: The DAA is an algorithm based on the DES cipher block chaining mode.
6. What is the full-form of CMAC?
a) Code-based MAC
b) Cipher-based MAC
c) Construct-based MAC
d) Collective-based MAC
Answer: b
Clarification: CMAC stands for cipher-based message authentication code.
7. Which cryptographic algorithm is used in CMAC?
a) Triple DES and AES
b) DES
c) RC-4
d) AES
Answer: a
Clarification: The CMAC algorithm uses triple DES and AES.
8. In CMAC, which scenario is a different key K2 is used instead of K1?
a) If the tag is larger than the key length
b) If the tag is shorter than the key length
c) In the last step of the algorithm
d) If the plaintext/message is not an integer multiple of the cipher clock length
Answer: d
Clarification: If the plaintext/message is not an integer multiple of the cipher clock length, then K2 is used.
9. K2 is derived by left shifting L by 2 bits. What is L defined as?
a) E(K , 0b)
b) E(K , 10*b)
c) E(K , 1b)
d) E(K , 10*1b)
Answer: a
Clarification: L is defined as encrypting b-bits of 0s with the key K through the same algorithm.