MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 31 Mcqs, each offering curated multiple-choice questions to sharpen your Cryptography and Network Security knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Assume input 10-bit key, K: 1010000010 for the SDES algorithm. What is K2? |
| A. | 10100111 |
| B. | 01000011 |
| C. | 00100100 |
| D. | 01011010 |
| Answer» C. 00100100 | |
| 2. |
In the DES algorithm the 64 bit key input is shortened to 56 bits by ignoring every 4th bit. |
| A. | True |
| B. | False |
| C. | May be |
| D. | Can't say |
| Answer» C. May be | |
| 3. |
The number of unique substitution boxes in DES after the 48 bit XOR operation are |
| A. | 8 |
| B. | 4 |
| C. | 6 |
| D. | 12 |
| Answer» B. 4 | |
| 4. |
The number of tests required to break the DES algorithm are |
| A. | 2.8×10^14 |
| B. | 4.2×10^9 |
| C. | 1.84×10^19 |
| D. | 7.2×10^16 |
| Answer» E. | |
| 5. |
The Plaintext for the Ciphertext 00001111, given that the key is 1111111111 is |
| A. | 01100111 |
| B. | 00001010 |
| C. | 11111111 |
| D. | 01101101 |
| Answer» D. 01101101 | |
| 6. |
Using Differential Crypt-analysis, the minimum computations required to decipher the DES algorithm is |
| A. | 2^56 |
| B. | 2^43 |
| C. | 2^55 |
| D. | 2^47 |
| Answer» E. | |
| 7. |
In triple DES, the key size is ___ and meet in the middle attack takes ___ tests to break the key. |
| A. | 2192 ,2112 |
| B. | 2184,2111 |
| C. | 2168,2111 |
| D. | 2168,2112 |
| Answer» E. | |
| 8. |
Assume input 10-bit key, K: 0010010111 for the SDES algorithm. What is K1? |
| A. | 00101111 |
| B. | 01011011 |
| C. | 01101000 |
| D. | 10100111 |
| Answer» B. 01011011 | |
| 9. |
The Plaintext for the Ciphertext 11110000, given that the key is 0000000000 is |
| A. | 01100111 |
| B. | 00000000 |
| C. | 01001000 |
| D. | 01101100 |
| Answer» C. 01001000 | |
| 10. |
Assume input 10-bit key, K: 0010010111 for the SDES algorithm. What is K2? |
| A. | 11101010 |
| B. | 11011011 |
| C. | 01101000 |
| D. | 10101111 |
| Answer» B. 11011011 | |
| 11. |
The Plaintext for the Ciphertext 10100101, given that the key is 0010010111 is |
| A. | 01100111 |
| B. | 00110110 |
| C. | 01001000 |
| D. | 01001100 |
| Answer» C. 01001000 | |
| 12. |
Using Linear Crypt-analysis, the minimum computations required to decipher the DES algorithm is |
| A. | 2^48 |
| B. | 2^43 |
| C. | 2^56 |
| D. | 2^64 |
| Answer» C. 2^56 | |
| 13. |
During decryption, we use the Inverse Initial Permutation (IP-1) before the IP. |
| A. | True |
| B. | False |
| C. | May be |
| D. | Can't say |
| Answer» B. False | |
| 14. |
A preferable cryptographic algorithm should have a good avalanche effect. |
| A. | True |
| B. | False |
| C. | May be |
| D. | Can't say |
| Answer» B. False | |
| 15. |
How many keys does the Triple DES algorithm use? |
| A. | 2 |
| B. | 3 |
| C. | 2 or 3 |
| D. | 3 or 4 |
| Answer» D. 3 or 4 | |
| 16. |
In SDES, Encryption algorithm can be written as a composition of functions:IP-1 o fK2 o fK1 o SW o IP |
| A. | True |
| B. | False |
| C. | May be |
| D. | Can't say |
| Answer» C. May be | |
| 17. |
The number of tests required to break the Double DES algorithm are |
| A. | 2112 |
| B. | 2111 |
| C. | 2128 |
| D. | 2119 |
| Answer» C. 2128 | |
| 18. |
The S-Box is used to provide confusion, as it is dependent on the unknown key. |
| A. | True |
| B. | False |
| C. | May be |
| D. | Can't say |
| Answer» B. False | |
| 19. |
If the key is 110100001 where,If ki=0, then S_i (x)=((1 1 0 | 0 1 1 | 1 0 0 ))x+((1 1 1))and If ki=1, then S_i (x)=((0 1 1 | 1 0 1 | 1 0 0))x+((0 1 1))then the output of the SP network for the plaintext: 101110001 is |
| A. | 010110011 |
| B. | 111000011 |
| C. | 110110111 |
| D. | 010110110 |
| Answer» B. 111000011 | |
| 20. |
Confusion hides the relationship between the ciphertext and the plaintext. |
| A. | True |
| B. | False |
| C. | May be |
| D. | Can't say |
| Answer» C. May be | |
| 21. |
Which of the following slows the cryptographic algorithm –1) Increase in Number of rounds2) Decrease in Block size3) Decrease in Key Size4) Increase in Sub key Generation |
| A. | 1 and 3 |
| B. | 2 and 3 |
| C. | 3 and 4 |
| D. | 2 and 4 |
| Answer» C. 3 and 4 | |
| 22. |
In affine block cipher systems if f(m)=Am + t, what is f(m1+m2+m3) ? |
| A. | f(m1) + f(m2) + f(m3) + t |
| B. | f(m1) + f(m2) + f(m3) +2t |
| C. | f(m1) + f(m2) + f(m3) |
| D. | 2(f(m1) + f(m2) + f(m3)) |
| Answer» D. 2(f(m1) + f(m2) + f(m3)) | |
| 23. |
IN_THE_DES_ALGORITHM_THE_64_BIT_KEY_INPUT_IS_SHORTENED_TO_56_BITS_BY_IGNORING_EVERY_4TH_BIT.?$ |
| A. | True |
| B. | False |
| Answer» C. | |
| 24. |
The number of unique substitution boxes in DES after the 48 bit XOR operation ar? |
| A. | 8 |
| B. | 4 |
| C. | 6 |
| D. | 12 |
| Answer» B. 4 | |
| 25. |
The Initial Permutation table/matrix is of size |
| A. | 16√ó8 |
| B. | 12√ó8 |
| C. | 8√ó8 |
| D. | 4√ó8 |
| Answer» D. 4‚Äö√†√∂‚àö‚â•8 | |
| 26. |
In the DES algorithm the Round Input is 32 bits, which is expanded to 48 bits via ____________ |
| A. | Scaling of the existing bits |
| B. | Duplication of the existing bits |
| C. | Addition of zeros |
| D. | Addition of ones |
| Answer» B. Duplication of the existing bits | |
| 27. |
In the DES algorithm the round key is __________ bit and the Round Input is ____________bits. |
| A. | 48, 32 |
| B. | 64,32 |
| C. | 56, 24 |
| D. | 32, 32 |
| Answer» B. 64,32 | |
| 28. |
In the DES algorithm, although the key size is 64 bits only 48bits are used for the encryption procedure, the rest are parity bits. |
| A. | True |
| B. | False |
| Answer» C. | |
| 29. |
The DES algorithm has a key length of |
| A. | 128 Bits |
| B. | 32 Bits |
| C. | 64 Bits |
| D. | 16 Bits |
| Answer» D. 16 Bits | |
| 30. |
The DES Algorithm Cipher System consists of ____________rounds (iterations) each with a round key |
| A. | 12 |
| B. | 18 |
| C. | 9 |
| D. | 16 |
| Answer» E. | |
| 31. |
DES follows |
| A. | Hash Algorithm |
| B. | Caesars Cipher |
| C. | Feistel Cipher Structure |
| D. | SP Networks |
| Answer» D. SP Networks | |