Data Integrity Algorithms Questions and Answers – CCM, GCM and Key Wrapping – II

This set of Cryptography Multiple Choice Questions & Answers (MCQs) focuses on “CCM, GCM and Key Wrapping”.

1. In GCM, we define S as S = GHASH(A||0^v||C||0^u||[len(A)]||[len(C)]). What is v defined as?
a) 64 ceil[len (A)/128] – len (A)
b) 64 ceil[len (C)/128] – len (C)
c) 128 ceil[len (A)/128] – len (A)
d) 128 ceil[len (C)/128] – len (C)
View Answer

2. When the length of the IV is not 96, then
a) we append the rest of the bits with 1*0 to make it 128 bits
b) we append the rest of the bits with 0*1 to make it 128 bits
c) we append the rest of the bits with 1*0 to make it 256 bits
d) we append the rest of the bits with 0s to make it 128 bits
View Answer

3. Which is not true for Key-Wrapping?
a) Used for small Plain Texts
b) It has a relatively higher throughput than other modes
c) It has block size of 64 bits
d) It has n+1 cipher blocks, for n plaintext block
View Answer

4. What is the value of A (0)?
a) F9*
b) A9*
c) A6*
d) F6*
View Answer

5. The cipher block is one block longer than the plaintext to accommodate the IV.
a) True
b) False
View Answer

6. The key Wrapping Algorithm provides confidentiality and data integrity.
a) True
b) False
View Answer

7. Which of the following is a valid disadvantage of the PRNG based on MAC function?
a) It has a high throughput
b) It takes twice the execution time
c) It is hardware intensive and can only work on high end processors
d) none of the mentioned
View Answer

8. “Specify in the correct order (from top to bottom), which Pseudo Random Number Generation schemes are represented here?
i)
m = [ n/outlen] w_o = V
W = the null string
For i = 1 to m
w_i = MAC(K,w_i-1)
W = W || wi
Return leftmost n bits of W
ii)
m = [n/outlen] W = the null string
For i = 1 to m
w_i = MAC(K,V || i)
W = W || w_i
Return leftmost n bits of W
iii)
m = [n/outlen] A(0) = V
W = the null string
For I = 1 to m
A(i) = MAC (K,A(i-1))
w_i = MAC (K, a(I) || v)
W = W || w_i
Return leftmost n bits of W”

a) NIST SP 800-90 ; TLS/WTLS ; IEEE 802.11
b) TLS/WTLS ; NIST SP 800-90 ; IEEE 802.11
c) IEEE 802.11 ; NIST SP 800-90 ; TLS/WTLS
d) NIST SP 800-90 ; IEEE 802.11 ; TLS/WTLS

Sanfoundry Global Education & Learning Series – Cryptography and Network Security.

To practice all areas of Cryptography and Network Security, here is complete set of 1000+ Multiple Choice Questions and Answers.