"V.V.P. ENGINEERING COLLEGE"
Department of Information Technology
"Question Bank - A.Y. 2023 - 2024"
Semester/Division
Name of Subject
Subject Code
Faculty 1
Sr.
No.
1
Un
it
1
1.1
1
2
1
3
1
4
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Question
6th/D
Cryptography & Network Security
3161606
Prof. Darshan Upadhyay
Marks
List and explain various types/categories of attacks 4
on information. OR Explain the two types of attacks
in detail. (active and passive)
Ans pg 38 of 6th edit.
When an encryption scheme is said to be
4
unconditionally secure and computationally secure?
Ans pg 56 of 6th
Explain the various types of cryptanalytic attack, 4
based on the amount of information known to the
cryptanalyst. OR Which two methods are used to
frustrate statistical cryptanalysis? OR Explain
Different type of Attacks on Crypto System.
Ans pg 55 of 6th
90 of 6th
38 of 6th
Blooms
CO
Taxonomy
R
CO1
U
CO2
U
CO2
Explain Security Services. OR
7
Explain data confidentiality, data authentication 3
and data integrity
Ans pg 40 of 6th
Explain Security Mechanisms.
7
th
Ans pg 43 of 6
R
CO1
R
CO1
Explain cipers with example: Playfair Cipher, Hill 4(For
Cipher, monoalphabetic Cipher, transposition each
ciphers(Reil fence cipher OR columnar transposition Cipher
Cipher) , One
time pad(Vernam Cipher),
U/C
CO2
Polyalphabetic cipher(Vigenere Cipher)
Ans pg 62 64
6
2
7
2
8
2
9
2
10
What is Avalanche Effect? What is diffusion and
confusion? Differentiate confusion and diffusion.
Pg 98
Draw and explain Feistel’s structure for encryption
and decryption. The exact realization of Feistel
network depends on the choice of which
parameters?
Pg 91
Explain Sbox in DES. what is the role of sbox in DES.
OR
Explain how DES(Data Encryption standard)
algorithm observes Fiestel structure. Explain key
generation and use of S-box in DES algorithm.
Pg 95
Explain single round function of DES with suitable
diagram.
Pg 82 5th ed
Pg 120 4th
4
U
CO2
7
U
CO2
4
U
CO2
7
R
CO2
2
Explain the triple DES scheme with two keys and 7
write about proposed attacks on 3DES.
Ans pg 200 6th
Pg 198 6th
U
CO2
11
2
Explain Double DES. Explain meet in-the middle 4/7
attack in DES.
Pg 198 6th
U
CO2
12
2
R
CO2
13
3
Explain AES or Explain the four function of AES
7
th
Pg 179 5
Why mode of operation is defined? List various 7
modes of operations of block cipher. Explain them
briefly.
Pg 204 6th
4
OR
Explain working of ECB.Why ECB (Electronic code
book) is rarely used to encrypt message?
4
th
Pg 205 6
E
CO2
OR
Why CFB(Cipher feedback mode) encrypted
messages are less subject to tampering than
OFB(Output feedback mode)?
Pg 208 cfb
Pg 210 ofb
One advantage of the OFB method is that bit errors in
transmission do not
propagate. For example, if a bit error occurs in C1, only the
recovered value of P1 is
affected; subsequent plaintext units are not corrupted. With
CFB, C1 also serves as
input to the shift register and therefore causes additional
corruption downstream.
The disadvantage of OFB is that it is more vulnerable to a
message stream
modification attack than is CFB. Consider that complementing
a bit in the ciphertext
complements the corresponding bit in the recovered plaintext.
Thus, controlled changes to the recovered plaintext can be
made. This may make it possible for an
opponent, by making the necessary changes to the checksum
portion of the message
as well as to the data portion, to alter the ciphertext in such a
way that it is not detected
by an error-correcting code. For a further discussion, see
[VOYD83].
OFB has the structure of a typical stream cipher, because the
cipher generates
a stream of bits as a function of an initial value and a key, and
that stream of
bits is XORed with the plaintext bits (see Figure 3.1). The
generated stream that is
XORed with the plaintext is itself independent of the plaintext;
this is highlighted
by dashed boxes in Figure 6.6. One distinction from the stream
ciphers we discuss
in Chapter 7 is that OFB encrypts plaintext a full block at a
time, where typically a
block is 64 or 128 bits. Many stream ciphers encrypt one byte
at a time
14
4
Differentiate Symmetric and Asymmetric key
cryptography. OR Compare conventional encryption
with public key encryption.
E
CO2