1
The block size of DES is
Correct Answer
64 bits
☑ MCQ PRACTICE
Cryptography and Network Security Unit 2
Practice objective questions for quick revision and examination preparation. Try answering each question before revealing the answer.
Cryptography and Network Security MCQs - Unit 2
2
The effective key size of DES is
Correct Answer
56 bits
3
The number of rounds in DES is
Correct Answer
16
4
The block size of AES is
Correct Answer
128 bits
5
AES supports key sizes of
Correct Answer
128, 192 and 256 bits
6
The number of rounds in AES with a 128-bit key is
Correct Answer
10
7
Which of the following is NOT a step in an AES round?
Correct Answer
Initial permutation
8
The block size of Blowfish is
Correct Answer
64 bits
9
The key length of Blowfish can vary from
Correct Answer
32 to 448 bits
10
RC5 is a symmetric block cipher whose block size, number of rounds and key length are
Correct Answer
all variable
11
IDEA uses a key of
Correct Answer
128 bits
12
The effective key length of Triple DES with three different keys is
Correct Answer
168 bits
13
A weakness of ECB mode is that
Correct Answer
identical plaintext blocks give identical ciphertext blocks
14
Which block cipher mode requires an initialization vector (IV) and chains blocks together?
Correct Answer
CBC
15
Which of the following modes lets a block cipher work like a stream cipher?
Correct Answer
CTR
16
RC4 is a
Correct Answer
stream cipher
17
RC4 uses a state array S of how many bytes?
Correct Answer
256
18
The security of RSA is based on the difficulty of
Correct Answer
factoring a large number into primes
19
In RSA, if p = 3 and q = 11, then n is
Correct Answer
33
20
In RSA with p = 3, q = 11 and public exponent e = 7, the private exponent d is
Correct Answer
3
21
The Diffie-Hellman algorithm is used for
Correct Answer
key exchange
22
The security of Diffie-Hellman key exchange is based on
Correct Answer
the discrete logarithm problem
23
ElGamal cryptography is based on
Correct Answer
the discrete logarithm problem
24
The Merkle-Hellman knapsack cryptosystem uses a
Correct Answer
super-increasing sequence
25
Which of the following is NOT a Feistel cipher?
Correct Answer
AES
Fill in the Blanks
26
DES performs ______ rounds of processing.
Correct Answer
16
27
The DES key is 64 bits long including ______ parity bits.
Correct Answer
8
28
The AES state is a ______ matrix of bytes.
Correct Answer
4 × 4
29
AES with a 256-bit key uses ______ rounds.
Correct Answer
14
30
Triple DES with three different keys has an effective key length of ______ bits.
Correct Answer
168
31
In ______ mode, each plaintext block is XORed with the previous ciphertext block before encryption.
Correct Answer
CBC (Cipher Block Chaining)
32
Blowfish uses a ______-round Feistel network.
Correct Answer
16
33
RC4 is a ______ cipher.
Correct Answer
stream
34
In RSA, φ(n) = ______.
Correct Answer
(p − 1)(q − 1)
35
In RSA with p = 5 and q = 7, the value of φ(n) is ______.
Correct Answer
24
36
In Diffie-Hellman with q = 23, α = 5, XA = 6 and XB = 15, the shared secret key is ______.
Correct Answer
2
37
An ElGamal ciphertext consists of ______ values (C1, C2).
Correct Answer
two
38
A sequence in which each element is greater than the sum of all previous elements is called a ______ sequence.
Correct Answer
super-increasing
39
The IDEA cipher uses a ______-bit key.
Correct Answer
128
40
The attack in which an attacker intercepts and relays Diffie-Hellman public values is the ______ attack.
Correct Answer
man-in-the-middle