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web.groovymark@gmail.com
- November 28, 2024
Question 01
Which of the following best describes the concept of “non-repudiation” in cryptography?
a) Ensuring that a message cannot be decrypted without the correct key
b) Preventing the sender from denying they sent a message
c) Securing communications against eavesdropping
d) Ensuring data integrity during transmission
Correct Answer: b) Preventing the sender from denying they sent a message
Explanation: Non-repudiation ensures that the sender of a message cannot deny having sent it, typically achieved using digital signatures.
Question 02
What is the primary characteristic of a public key in asymmetric encryption?
a) It is used for decryption only
b) It is kept secret and shared only with trusted parties
c) It is used for encryption and can be freely distributed
d) It is faster than symmetric encryption
Correct Answer: c) It is used for encryption and can be freely distributed
Explanation: In asymmetric encryption, the public key is used for encryption and can be freely distributed, while the private key is kept secret and used for decryption.
Question 03
Which of the following describes the main difference between RSA and Elliptic Curve Cryptography (ECC)?
a) RSA is faster than ECC
b) ECC requires smaller key sizes for equivalent security
c) RSA uses fewer computational resources than ECC
d) ECC is less secure than RSA
Correct Answer: b) ECC requires smaller key sizes for equivalent security
Explanation: ECC provides the same level of security as RSA but with much smaller key sizes, making it more efficient in terms of storage and computation.
Question 04
What is the primary function of a digital certificate?
a) To encrypt messages during transmission
b) To provide authentication and public key verification
c) To generate symmetric keys
d) To secure communications using hashing
Correct Answer: b) To provide authentication and public key verification
Explanation: A digital certificate is used to verify the identity of an entity and associate it with a public key for secure communications.
Question 05
Which of the following cryptographic techniques provides forward secrecy?
a) RSA
b) Diffie-Hellman
c) SHA-256
d) MD5
Correct Answer: b) Diffie-Hellman
Explanation: Diffie-Hellman provides forward secrecy by ensuring that session keys are not derived from long-term keys, preventing compromise of past sessions.
Question 06
Which of the following encryption modes uses a counter and allows parallel processing of blocks?
a) ECB
b) CBC
c) CFB
d) CTR
Correct Answer: d) CTR
Explanation: Counter (CTR) mode allows for parallel processing of blocks because each block is encrypted independently, improving encryption performance.
Question 07
Which of the following describes a “replay attack”?
a) An attacker intercepts and reuses valid data transmissions
b) An attacker modifies encrypted messages in transit
c) An attacker decrypts a message using brute force
d) An attacker injects malicious code into encrypted data
Correct Answer: a) An attacker intercepts and reuses valid data transmissions
Explanation: A replay attack involves capturing and reusing legitimate data transmissions, often to gain unauthorized access or deceive systems.
Question 08
What is the key length for AES-128 encryption?
a) 128 bits
b) 192 bits
c) 256 bits
d) 64 bits
Correct Answer: a) 128 bits
Explanation: AES-128 uses a 128-bit key for encryption, providing a balance between security and performance.
Question 09
Which of the following cryptographic attacks involves analyzing the time taken to execute encryption operations to deduce the key?
a) Side-channel attack
b) Brute-force attack
c) Replay attack
d) Man-in-the-middle attack
Correct Answer: a) Side-channel attack
Explanation: In a side-channel attack, the attacker analyzes the time, power consumption, or other physical characteristics of encryption operations to gather information about the encryption key.
Question 10
Which of the following cryptographic protocols is used for secure key exchange over an untrusted network?
a) AES
b) RSA
c) Diffie-Hellman
d) SHA-1
Correct Answer: c) Diffie-Hellman
Explanation: Diffie-Hellman is a key exchange protocol that allows two parties to securely exchange cryptographic keys over an untrusted network.
Question 11
What is the primary role of hashing in digital signatures?
a) To encrypt the data
b) To provide confidentiality
c) To ensure data integrity
d) To establish a secure communication channel
Correct Answer: c) To ensure data integrity
Explanation: Hashing in digital signatures ensures that the data has not been altered by creating a unique hash of the data, which is signed by the sender for verification by the recipient.
Question 12
Which of the following describes the Caesar cipher?
a) A transposition cipher
b) A stream cipher
c) A substitution cipher that shifts letters by a fixed number
d) A block cipher that operates in parallel
Correct Answer: c) A substitution cipher that shifts letters by a fixed number
Explanation: The Caesar cipher is a simple substitution cipher that shifts each letter of the plaintext by a fixed number of positions in the alphabet.
Question 13
What is the primary advantage of using elliptic curve cryptography (ECC) in mobile devices?
a) It provides faster encryption than RSA
b) It uses smaller key sizes, requiring less computational power
c) It is more secure than other encryption methods
d) It uses symmetric encryption, which is faster
Correct Answer: b) It uses smaller key sizes, requiring less computational power
Explanation: ECC uses smaller key sizes compared to RSA, making it more efficient for mobile devices with limited computational power.
Question 14
Which of the following describes a chosen-plaintext attack?
a) The attacker chooses plaintext to encrypt and observe the resulting ciphertext
b) The attacker intercepts and decrypts ciphertext without knowing the key
c) The attacker selects ciphertext to be decrypted and analyzes the plaintext
d) The attacker modifies the ciphertext in transit
Correct Answer: a) The attacker chooses plaintext to encrypt and observe the resulting ciphertext
Explanation: In a chosen-plaintext attack, the attacker selects plaintext to encrypt and uses the resulting ciphertext to gather information about the encryption algorithm.
Question 15
Which of the following block cipher modes of operation ensures that each ciphertext block depends on all previous blocks?
a) ECB
b) CBC
c) CTR
d) OFB
Correct Answer: b) CBC
Explanation: Cipher Block Chaining (CBC) mode ensures that each ciphertext block depends on the encryption of the previous block, making it more secure than ECB.
Question 16
What is the primary purpose of a cryptographic nonce?
a) To store a secret key
b) To ensure that identical plaintexts produce different ciphertexts
c) To generate a digital signature
d) To provide authentication
Correct Answer: b) To ensure that identical plaintexts produce different ciphertexts
Explanation: A nonce is a random value used only once in encryption to ensure that the same plaintext encrypted multiple times results in different ciphertexts.
Question 17
Which of the following describes a public key in asymmetric encryption?
a) It is used for encryption and can be freely distributed
b) It is used for decryption and must be kept secret
c) It is used for hashing and digital signatures
d) It is faster than symmetric encryption
Correct Answer: a) It is used for encryption and can be freely distributed
Explanation: In asymmetric encryption, the public key is used for encryption and can be freely distributed, while the private key is kept secret for decryption.
Question 18
Which cryptographic algorithm is typically used for digital signatures?
a) AES
b) RSA
c) DES
d) RC4
Correct Answer: b) RSA
Explanation: RSA is commonly used for digital signatures because it provides authentication and data integrity by allowing the recipient to verify the identity of the sender.
Question 19
What is the primary purpose of salting in password hashing?
a) To encrypt the password before hashing
b) To ensure that the same password generates different hash values
c) To compress the password into a fixed length
d) To generate a secret key
Correct Answer: b) To ensure that the same password generates different hash values
Explanation: Salting adds random data to passwords before hashing to ensure that identical passwords result in different hash values, preventing attackers from using precomputed tables to crack hashes.
Question 20
Which of the following encryption methods is used to secure Wi-Fi networks under WPA2?
a) RSA
b) AES
c) DES
d) ECC
Correct Answer: b) AES
Explanation: AES is used to secure Wi-Fi networks under WPA2, providing strong encryption to protect wireless communications.
