This set of Cryptography Multiple Choice Questions & Answers (MCQs) focuses on “Pseudorandom Number Generators and Stream Ciphers”.
1. Using the Linear Congruential Method (LCM), for a=7, c=0 and m=32. The period is
a) 13
b) 4
c) 11
d) 7
View Answer
Explanation: The sequence generated is {7,17,23,1,7..}. Thus the period is 4.
2. Using the Linear Congruential Method, for a=5, c=0 and m=32. The period is
a) 8
b) 4
c) 9
d) 11
View Answer
Explanation: The sequence generated is {2,25,29,17,21,9,13,1,5,2…}. Thus the period is 8.
3. The appropriate value for m (in LCM) is
a) 2(31) – 1
b) 2(31)
c) 2(32)
d) 2(32) – 1
View Answer
Explanation: Typically 2^(31) – 1 is chosen as the value for m (a large prime number).
4. A CSPRBG is defined as one that passes the __ test.
a) Runs test
b) Maurer’s Universal statistical test
c) Frequency Test
d) On-bit test
View Answer
Explanation: A CSPRBG is defined as one that passes the one-bit test.
5. Find the first 8 bits for Blum Blum Shub Bit Generator when seed = 101355 and n = 192649.
a) 10101010
b) 11100010
c) 11001011
d) 11001110
View Answer
Explanation: The blum blum shub algorithm is as follows-
Xo = s2 mod n
for i=1 to 8
Xi = X(i-1)2 mod n
Bi = Xi mod 2
Using this we compute the bits as – 11001110.
6. Which of these modes is an appropriate mode for PRNG?
a) ECB
b) CBC
c) CFB
d) CTR
View Answer
Explanation: CTR and OFB are suitable modes for PRNG.
7. Which mode is recommend for the X9.82 Random number generator?
a) OFB
b) CBC
c) CFB
d) CTR
View Answer
Explanation: OFB is the recommended mode for the X9.82 Random number generator.
8. AES PRNG produces bits outputs of size
a) 512 bits
b) 128 bits
c) 256 bits
d) 64 bits
View Answer
Explanation: AES PRNG produces bits outputs of size 128 bits.
9. Which mode is recommend for the ANSI standard X9.82 Random number generator?
a) OFB
b) CTR
c) CFB
d) CFB
View Answer
Explanation: CTR is the recommended mode for the ANSI standard X9.82 Random number generator.
10. The CTR algorithm for PRNG is known as
a) CTR_PRNG
b) X-SESS
c) CTR-SESS
d) CTR_DRBG
View Answer
Explanation: The CTR algorithm for PRNG is known as CTR_DRBG.
11. Which mode is recommend for the RFC 4086 Random number generator?
a) CFB
b) CBC
c) OFB
d) CTR
View Answer
Explanation: OFB is the recommended mode for the RFC 4086 Random number generation.
12. while (len(temp) < requested_number_of_bits) do
V = E(Key, V)
temp = temp || V
The above algorithm is for the CTR mode.
a) True
b) False. It is for the ECB mode
c) False. It is for the OFB mode
d) False. It is for the CFB mode
View Answer
Explanation: The algorithm above is the OFB mode representation.
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.
- Practice Computer Science MCQs
- Check Computer Science Books
- Practice Cyber Security MCQ
- Apply for Computer Science Internship
- Check Cryptography and Network Security Books