MCQOPTIONS
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MCQOPTIONS
This section includes 12 Mcqs, each offering curated multiple-choice questions to sharpen your Cryptography knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Meet in the middle attack is an attack |
| A. | where the timing required for the attack via brute force is drastically reduced |
| B. | where the adversary uses 2 or more machines to decrypt thus trying to reduce the time |
| C. | where messages are intercepted and then either relayed or substituted with another message |
| D. | where cryptanalysis takes lesser time than the brute force decryption |
| Answer» D. where cryptanalysis takes lesser time than the brute force decryption | |
| 2. |
In Elgamal cryptosystem, given the prime p=31.What is the respective plaintext character for C = (27, 20)? |
| A. | H |
| B. | L |
| C. | O |
| D. | M |
| Answer» B. L | |
| 3. |
In Elgamal cryptosystem, given the prime p=31.Encrypt the message HELLO ; use 00 to 25 for encoding. The value of C2 for character L is |
| A. | 12 |
| B. | 07 |
| C. | 20 |
| D. | 27 |
| Answer» E. | |
| 4. |
10.Find the solution of x2 3 mod 23 |
| A. | x 16 mod 23 |
| B. | x 13 mod 23 |
| C. | x 22 mod 23 |
| D. | x 7 mod 23 |
| Answer» B. x 13 mod 23 | |
| 5. |
Which among the following values: 17, 20, 38, and 50, does not have primitive roots in the group G = <Zn , >? |
| A. | 17 |
| B. | 20 |
| C. | 38 |
| D. | 50 |
| Answer» C. 38 | |
| 6. |
Find the order of group G= <Z7*, x> |
| A. | 6 |
| B. | 4 |
| C. | 3 |
| D. | 5 |
| Answer» B. 4 | |
| 7. |
How many primitive roots does Z<19> have? |
| A. | 5 |
| B. | 8 |
| C. | 7 |
| D. | 6 |
| Answer» E. | |
| 8. |
Suppose that plaintext message units are single letters in the usual 26-letter alphabet with A-Z corresponding to 0-25. You receive the sequence of ciphertext message units 14, 25, 89. The public key is the sequence {57, 14, 3, 24, 8} and the secret key is b = 23, m = 61.Decipher the message. The Plain text is |
| A. | TIN |
| B. | INT |
| C. | KIN |
| D. | INK |
| Answer» C. KIN | |
| 9. |
The plaintext message consist of single letters with 5-bit numerical equivalents from (00000)2 to (11001)2. The secret deciphering key is the superincreasing 5-tuple (2, 3, 7, 15, 31), m = 61 and a = 17. Find the ciphertext for the message WHY . |
| A. | C= (148, 143, 50) |
| B. | C= (148, 143, 56) |
| C. | C= (143, 148, 92) |
| D. | C= (148, 132,92) |
| Answer» B. C= (148, 143, 56) | |
| 10. |
Consider knapsack that weighs 23 that has been made from the weights of the superincreasing series {1, 2, 4, 9, 20, and 38}. Find the n . |
| A. | 011111 |
| B. | 010011 |
| C. | 010111 |
| D. | 010010 |
| Answer» C. 010111 | |
| 11. |
For the point P (7, 0) defined in the curve E13(1, 1). What is P? |
| A. | (7,1) |
| B. | (8,12) |
| C. | (8,1) |
| D. | (7,0) |
| Answer» E. | |
| 12. |
Bob selects E67(2, 3) as the elliptic curve over GF(p). He selects e1 = (2, 22) and d = 4.Then he calculates e2 = d e1 and the publicly announces the tuple (E, e1, e2). Now, Alice wants to send the plaintext P = (24, 26) to Bob and she selects r = 2. What are C1 and C2? |
| A. | C1=(35,1) ; C2 =(21,44) |
| B. | C1=(44,21) ; C2 =(1,35) |
| C. | C1=(44,21) ; C2 =(44,21) |
| D. | C1=(21,44); C2 =(35,1) |
| Answer» B. C1=(44,21) ; C2 =(1,35) | |