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Cryptography Unit2

Total questions: 25

Worksheet time: 4mins

Name
Class
Date
1.

In symmetric key cryptography, the same key is used for:

a)
Encryption and decryption of data.
b)
Key generation and storage.
c)
Only decryption of data.
d)
Only encryption of data.
2.

Which of the following is a symmetric key algorithm?

a)
Blowfish
b)
SHA-256
c)
AES
d)
RSA
3.

DES stands for:

a)
Data Encryption Standard
b)
Data Encoding Standard
c)
Digital Encryption System
d)
Data Encryption Service
4.

DES has a block size of:

a)
64 bits
b)
256 bits
c)
32 bits
d)
128 bits
5.

The number of rounds in DES is:

a)
16
b)
12
c)
8
d)
20
6.

AES supports key sizes of:

a)
128, 192, and 256 bits
b)
128 and 512 bits
c)
128, 256, and 512 bits
d)
64, 128, and 192 bits
7.

The block size in AES is fixed at:

a)
64 bits
b)
256 bits
c)
128 bits
d)
512 bits
8.

The number of rounds in AES-128 is:

a)
8
b)
12
c)
14
d)
10
9.

Which operation is not used in AES?

a)
XOR
b)
Addition
c)
Subtraction
d)
Multiplication
10.

Linear cryptanalysis uses:

a)
Statistical analysis of the cipher's key.
b)
Brute force attacks on the cipher.
c)
Substitution techniques for encryption.
d)
Linear approximations of the cipher's behavior.
11.

Differential cryptanalysis studies:

a)
The efficiency of encryption algorithms.
b)
The history of cryptographic techniques.
c)
The mathematical foundations of number theory.
d)
The relationship between input and output differences in cryptographic algorithms.
12.

The avalanche effect ensures that:

a)
A small change in input has no effect on output.
b)
A small change in input results in a significant change in output.
c)
A large change in input results in a small change in output.
d)
The output remains constant regardless of input changes.
13.

A secure S-box must have:

a)
High redundancy
b)
Linear transformation
c)
Non-linearity, confusion, diffusion, balanced output, resistance to attacks.
d)
Static output
14.

One key S-box design principle is to:

a)
ensure non-linearity
b)
ensure simplicity
c)
maximize linearity
d)
reduce complexity
15.

ECB mode encrypts blocks:

a)
in groups of two blocks
b)
using a shared key for all blocks
c)
independently for each block
d)
with a fixed initialization vector
16.

CBC mode stands for:

a)
Cipher Bit Chaining
b)
Cipher Block Chaining
c)
Cipher Block Change
d)
Cipher Block Chaining Mode
17.

Which block cipher mode requires an IV (Initialization Vector)?

a)
Electronic Codebook (ECB)
b)
Output Feedback (OFB)
c)
Cipher Block Chaining (CBC)
d)
Counter (CTR)
18.

CTR mode stands for:

a)
Cipher mode
b)
Block mode
c)
Stream mode
d)
Counter mode
19.

Which is a disadvantage of ECB mode?

a)
It encrypts data more securely than other modes.
b)
It requires less computational power than other modes.
c)
It is the most widely used encryption mode.
d)
It reveals patterns in the plaintext.
20.

A stream cipher encrypts:

a)
only images and videos
b)
individual bits or bytes of data
c)
blocks of data in fixed sizes
d)
entire files of data
21.

Which is a popular stream cipher?

a)
RC4
b)
Blowfish
c)
AES
d)
DES
22.

Which technique targets cipher rounds individually?

a)
Linear cryptanalysis
b)
Block cipher mode analysis
c)
Key recovery attacks
d)
Differential cryptanalysis
23.

In differential cryptanalysis, a differential refers to:

a)
The difference between two input values.
b)
The average of two input values.
c)
The product of two input values.
d)
The sum of two input values.
24.

Which of the following is not a block cipher mode of operation?

a)
CTR (Counter mode)
b)
OFB (Output Feedback)
c)
CBC (Cipher Block Chaining)
d)
ECB (Electronic Codebook)
25.

A mode that turns a block cipher into a stream cipher is:

a)
Counter (CTR) mode
b)
Output Feedback (OFB) mode
c)
Electronic Codebook (ECB) mode
d)
Cipher Feedback (CFB) mode