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web.groovymark@gmail.com
- November 29, 2024
Question 01
Which of the following block cipher modes is the least secure because it encrypts identical blocks of plaintext into identical blocks of ciphertext?
a) CBC
b) CTR
c) ECB
d) OFB
Correct Answer: c) ECB
Explanation: ECB (Electronic Codebook) mode is considered insecure because identical plaintext blocks result in identical ciphertext blocks, making it vulnerable to pattern analysis attacks.
Question 02
Which of the following types of cryptographic attacks aims to recover plaintext from ciphertext without knowledge of the encryption key?
a) Brute-force attack
b) Cryptanalysis attack
c) Known-plaintext attack
d) Chosen-plaintext attack
Correct Answer: b) Cryptanalysis attack
Explanation: A cryptanalysis attack attempts to recover plaintext or encryption keys by analyzing the ciphertext and using various techniques without needing to know the key.
Question 03
Which of the following cryptographic algorithms is commonly used for encrypting files with full disk encryption?
a) RSA
b) AES
c) SHA-256
d) DES
Correct Answer: b) AES
Explanation: AES is commonly used in full disk encryption due to its strong security and efficiency.
Question 04
Which of the following algorithms is based on the difficulty of solving discrete logarithms?
a) RSA
b) ECC
c) AES
d) DES
Correct Answer: b) ECC
Explanation: Elliptic Curve Cryptography (ECC) relies on the difficulty of solving discrete logarithms, which is what provides its security.
Question 05
Which type of cipher involves rearranging the characters of the plaintext without changing the actual characters?
a) Substitution cipher
b) Transposition cipher
c) Stream cipher
d) Block cipher
Correct Answer: b) Transposition cipher
Explanation: A transposition cipher rearranges the characters of the plaintext, while a substitution cipher changes the characters to other symbols or letters.
Question 06
Which of the following encryption methods allows two parties to establish a shared secret over an insecure channel?
a) AES
b) RSA
c) Diffie-Hellman
d) SHA-256
Correct Answer: c) Diffie-Hellman
Explanation: Diffie-Hellman is used to securely establish a shared secret between two parties over an insecure channel, such as the internet.
Question 07
Which of the following best describes an active attack in cryptography?
a) An attacker attempts to decrypt ciphertext without altering it
b) An attacker attempts to modify or alter the communications between two parties
c) An attacker eavesdrops on communications without detection
d) An attacker uses brute-force methods to guess the encryption key
Correct Answer: b) An attacker attempts to modify or alter the communications between two parties
Explanation: An active attack involves modifying, intercepting, or altering the communications between two parties, whereas a passive attack involves eavesdropping without altering data.
Question 08
What is the key length for AES-192 encryption?
a) 128 bits
b) 192 bits
c) 256 bits
d) 64 bits
Correct Answer: b) 192 bits
Explanation: AES-192 uses a 192-bit key for encryption, providing a higher level of security than AES-128.
Question 09
Which of the following encryption algorithms is typically used for secure key exchange in public key infrastructure (PKI)?
a) AES
b) RSA
c) ECC
d) DES
Correct Answer: b) RSA
Explanation: RSA is commonly used for secure key exchange in PKI due to its use of public and private keys.
Question 10
Which of the following is a cryptographic technique used to ensure that data has not been altered?
a) Encryption
b) Hashing
c) Key exchange
d) Digital signature
Correct Answer: b) Hashing
Explanation: Hashing is used to ensure data integrity by generating a fixed-length hash value that can be compared to the original data to check for any changes.
Question 11
Which cryptographic attack involves attempting every possible key until the correct one is found?
a) Known-plaintext attack
b) Chosen-plaintext attack
c) Brute-force attack
d) Replay attack
Correct Answer: c) Brute-force attack
Explanation: A brute-force attack involves trying all possible combinations of keys until the correct key is found.
Question 12
Which of the following describes an asymmetric encryption algorithm?
a) It uses the same key for encryption and decryption
b) It uses different keys for encryption and decryption
c) It generates a fixed-length output from variable-length input
d) It uses a nonce for additional security
Correct Answer: b) It uses different keys for encryption and decryption
Explanation: Asymmetric encryption uses a public key for encryption and a private key for decryption, making it more secure for key exchange.
Question 13
What is the primary advantage of using elliptic curve cryptography (ECC) over RSA?
a) ECC is faster than RSA
b) ECC uses smaller key sizes for equivalent security
c) ECC is easier to implement than RSA
d) ECC is less secure than RSA
Correct Answer: b) ECC uses 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 computational resources.
Question 14
Which of the following block cipher modes uses an initialization vector (IV) and chains each block to the previous one?
a) ECB
b) CTR
c) CBC
d) OFB
Correct Answer: c) CBC
Explanation: Cipher Block Chaining (CBC) mode uses an initialization vector and chains each block to the previous one, making it more secure than ECB mode.
Question 15
Which of the following is a characteristic of a cryptographic hash function?
a) It is reversible
b) It generates a fixed-length output from a variable-length input
c) It requires a secret key for decryption
d) It uses block cipher modes
Correct Answer: b) It generates a fixed-length output from a variable-length input
Explanation: A cryptographic hash function generates a fixed-length output, called a hash, from a variable-length input and is used to ensure data integrity.
Question 16
Which of the following encryption modes allows for parallel processing of blocks?
a) ECB
b) CBC
c) CTR
d) CFB
Correct Answer: c) CTR
Explanation: Counter (CTR) mode allows for parallel processing of blocks because each block is encrypted independently, improving performance in high-speed environments
Question 17
What is the main weakness of the DES encryption algorithm?
a) It uses a small key size
b) It is a public-key encryption algorithm
c) It requires too much computational power
d) It is difficult to implement
Correct Answer: a) It uses a small key size
Explanation: DES uses a small key size of 56 bits, which makes it vulnerable to brute-force attacks.
Question 18
Which of the following cryptographic attacks involves intercepting communications between two parties and altering the data without their knowledge?
a) Man-in-the-middle attack
b) Replay attack
c) Known-plaintext attack
d) Side-channel attack
Correct Answer: a) Man-in-the-middle attack
Explanation: In a man-in-the-middle attack, the attacker intercepts and potentially alters the communication between two parties without their knowledge.
Question 19
Which of the following describes the concept of perfect forward secrecy?
a) It ensures that a message cannot be altered during transmission
b) It prevents attackers from reusing valid data transmissions
c) It ensures that past sessions remain secure even if long-term keys are compromised
d) It allows faster encryption and decryption
Correct Answer: c) It ensures that past sessions remain secure even if long-term keys are compromised
Explanation: Perfect forward secrecy ensures that even if long-term encryption keys are compromised, previous session keys remain secure.
Question 20
Which of the following best describes the function of a digital signature?
a) It encrypts a message for secure transmission
b) It verifies the identity of the sender and the integrity of the message
c) It generates a public and private key pair
d) It provides confidentiality for data in transit
Correct Answer: b) It verifies the identity of the sender and the integrity of the message
Explanation: A digital signature is used to verify the sender's identity and ensure that the message has not been tampered with.
