CS – D334 ITAS 2141 Introduction to
Cryptography
Comprehensive Objective Assessment (Qns &
Ans)
2025
Question 1 (Multiple Choice)
Question:
Which cryptographic technique uses a pair of mathematically
related keys for encryption and decryption, allowing secure
communication without a pre-shared secret?
A) Symmetric encryption
B) Asymmetric encryption
C) Hashing
D) Steganography
Correct ANS:
©2025
,B) Asymmetric encryption
Rationale:
Asymmetric encryption employs a public key for encryption and a
private key for decryption. This pair ensures that even if the
public key is widely distributed, only the holder of the private key
can decrypt the messages, making it ideal for secure
communications in environments where no prior secret is shared.
---
Question 2 (Fill in the Blank)
Question:
The attribute of an encryption algorithm whereby a small change
in the input (plaintext) produces a significant, unpredictable
change in the output (ciphertext) is known as the ________ .
Correct ANS:
Avalanche effect
Rationale:
The avalanche effect is critical for a robust cipher because it
ensures that the relationship between the plaintext, ciphertext, and
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,key is highly nonlinear. This property helps thwart statistical
attacks by making it nearly impossible to infer the key or plaintext
based on ciphertext patterns.
---
Question 3 (True/False)
Question:
In the RSA algorithm, the security relies on the computational
difficulty of factoring the product of two large prime numbers.
Correct ANS:
True
Rationale:
RSA’s strength is based on the mathematical challenge of
factorizing a large integer that is the product of two large primes.
Without efficient factorization algorithms, recovering the private
key from the public key remains computationally infeasible.
---
©2025
, Question 4 (Multiple Response)
Question:
Select all cryptographic primitives that provide data integrity
services:
A) Hash functions
B) Digital signatures
C) Symmetric encryption
D) Message Authentication Codes (MACs)
Correct ANS:
A, B, D
Rationale:
Hash functions, digital signatures, and MACs all serve to verify
data integrity—ensuring that data has not been altered. While
symmetric encryption secures confidentiality, it does not
inherently provide integrity unless combined with additional
techniques.
---
Question 5 (Multiple Choice)
©2025
Cryptography
Comprehensive Objective Assessment (Qns &
Ans)
2025
Question 1 (Multiple Choice)
Question:
Which cryptographic technique uses a pair of mathematically
related keys for encryption and decryption, allowing secure
communication without a pre-shared secret?
A) Symmetric encryption
B) Asymmetric encryption
C) Hashing
D) Steganography
Correct ANS:
©2025
,B) Asymmetric encryption
Rationale:
Asymmetric encryption employs a public key for encryption and a
private key for decryption. This pair ensures that even if the
public key is widely distributed, only the holder of the private key
can decrypt the messages, making it ideal for secure
communications in environments where no prior secret is shared.
---
Question 2 (Fill in the Blank)
Question:
The attribute of an encryption algorithm whereby a small change
in the input (plaintext) produces a significant, unpredictable
change in the output (ciphertext) is known as the ________ .
Correct ANS:
Avalanche effect
Rationale:
The avalanche effect is critical for a robust cipher because it
ensures that the relationship between the plaintext, ciphertext, and
©2025
,key is highly nonlinear. This property helps thwart statistical
attacks by making it nearly impossible to infer the key or plaintext
based on ciphertext patterns.
---
Question 3 (True/False)
Question:
In the RSA algorithm, the security relies on the computational
difficulty of factoring the product of two large prime numbers.
Correct ANS:
True
Rationale:
RSA’s strength is based on the mathematical challenge of
factorizing a large integer that is the product of two large primes.
Without efficient factorization algorithms, recovering the private
key from the public key remains computationally infeasible.
---
©2025
, Question 4 (Multiple Response)
Question:
Select all cryptographic primitives that provide data integrity
services:
A) Hash functions
B) Digital signatures
C) Symmetric encryption
D) Message Authentication Codes (MACs)
Correct ANS:
A, B, D
Rationale:
Hash functions, digital signatures, and MACs all serve to verify
data integrity—ensuring that data has not been altered. While
symmetric encryption secures confidentiality, it does not
inherently provide integrity unless combined with additional
techniques.
---
Question 5 (Multiple Choice)
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