D334 ITAS 2141 Intro to Cryptography
Final Assessment Review (Qns & Ans)
2025
Multiple Choice Questions
Which of the following algorithms is not a symmetric encryption
algorithm?
a) AES
b) DES
c) RSA
d) Blowfish
ANS: c) RSA
Rationale: RSA is an asymmetric encryption algorithm, while
AES, DES, and Blowfish are symmetric.
©2025
,What is the primary purpose of a hash function in cryptography?
a) To encrypt data
b) To generate random numbers
c) To verify data integrity
d) To establish a secure channel
ANS: c) To verify data integrity
Rationale: Hash functions are used to ensure that data has not
been altered.
Which of the following describes a one-time pad?
a) A reusable key
b) A key that is as long as the message
c) A symmetric key
d) An encryption scheme without any key
ANS: b) A key that is as long as the message
Rationale: A one-time pad uses a key that is the same length as
the message, providing perfect secrecy if used correctly.
What is the main vulnerability of the RSA algorithm?
a) Key length
©2025
,b) Public key exposure
c) Implementation flaws
d) Both a and c
ANS: d) Both a and c
Rationale: RSA is vulnerable to attacks if keys are not sufficiently
long and if proper implementation practices are not followed.
In a digital signature scheme, the private key is used to:
a) Encrypt the message
b) Encrypt the hash of the message
c) Decrypt the signature
d) Generate the hash
ANS: b) Encrypt the hash of the message
Rationale: The private key is used to sign by encrypting the hash
of the message, allowing verification with the public key.
Fill-in-the-Blank Questions
The principle of __________ states that a cryptographic key must
remain secret to ensure security.
ANS: Confidentiality
Rationale: Confidentiality ensures that data remains private and
secure from unauthorized access.
©2025
, The process of transforming plaintext into ciphertext is known as
__________.
ANS: Encryption
Rationale: Encryption is the method of converting data into a
format that cannot be understood without a key.
A __________ attack is when an adversary tries all possible keys
to decrypt a message.
ANS: Brute-force
Rationale: Brute-force attacks involve systematically checking all
possible keys until the correct one is found.
The __________ is a mathematical function used to combine
input data into a fixed-size output, commonly used in hashing.
ANS: Hash function
Rationale: Hash functions transform variable-length data into a
fixed-length hash, preserving data integrity.
Public key infrastructure (PKI) relies on __________ to verify the
ownership of public keys.
ANS: Digital certificates
©2025
Final Assessment Review (Qns & Ans)
2025
Multiple Choice Questions
Which of the following algorithms is not a symmetric encryption
algorithm?
a) AES
b) DES
c) RSA
d) Blowfish
ANS: c) RSA
Rationale: RSA is an asymmetric encryption algorithm, while
AES, DES, and Blowfish are symmetric.
©2025
,What is the primary purpose of a hash function in cryptography?
a) To encrypt data
b) To generate random numbers
c) To verify data integrity
d) To establish a secure channel
ANS: c) To verify data integrity
Rationale: Hash functions are used to ensure that data has not
been altered.
Which of the following describes a one-time pad?
a) A reusable key
b) A key that is as long as the message
c) A symmetric key
d) An encryption scheme without any key
ANS: b) A key that is as long as the message
Rationale: A one-time pad uses a key that is the same length as
the message, providing perfect secrecy if used correctly.
What is the main vulnerability of the RSA algorithm?
a) Key length
©2025
,b) Public key exposure
c) Implementation flaws
d) Both a and c
ANS: d) Both a and c
Rationale: RSA is vulnerable to attacks if keys are not sufficiently
long and if proper implementation practices are not followed.
In a digital signature scheme, the private key is used to:
a) Encrypt the message
b) Encrypt the hash of the message
c) Decrypt the signature
d) Generate the hash
ANS: b) Encrypt the hash of the message
Rationale: The private key is used to sign by encrypting the hash
of the message, allowing verification with the public key.
Fill-in-the-Blank Questions
The principle of __________ states that a cryptographic key must
remain secret to ensure security.
ANS: Confidentiality
Rationale: Confidentiality ensures that data remains private and
secure from unauthorized access.
©2025
, The process of transforming plaintext into ciphertext is known as
__________.
ANS: Encryption
Rationale: Encryption is the method of converting data into a
format that cannot be understood without a key.
A __________ attack is when an adversary tries all possible keys
to decrypt a message.
ANS: Brute-force
Rationale: Brute-force attacks involve systematically checking all
possible keys until the correct one is found.
The __________ is a mathematical function used to combine
input data into a fixed-size output, commonly used in hashing.
ANS: Hash function
Rationale: Hash functions transform variable-length data into a
fixed-length hash, preserving data integrity.
Public key infrastructure (PKI) relies on __________ to verify the
ownership of public keys.
ANS: Digital certificates
©2025
