WorksheetsCryptography Quiz
Total questions: 10
Worksheet time: 5mins
Which of the following correctly differentiates a stream cipher from a block cipher?
Stream ciphers encrypt fixed-size blocks, while block ciphers encrypt individual bits.
Stream ciphers operate on continuous streams of data, while block ciphers work on discrete blocks of bits.
Both encrypt fixed-size data blocks but differ in key length.
Stream ciphers and block ciphers use identical key scheduling techniques.
Which of the following stream ciphers uses a synchronous keystream generator approach?
RC4
DES
AES
Blowfish
In symmetric key cryptography, the primary challenge is:
Large key sizes affecting computational efficiency
Secure key distribution between sender and receiver
High computational complexity of public key operations
Vulnerability to chosen-ciphertext attacks only
Which block cipher mode of operation turns a block cipher into a self-synchronizing stream cipher?
Cipher Block Chaining (CBC)
Cipher Feedback Mode (CFB)
Output Feedback Mode (OFB)
Counter Mode (CTR)
A stream cipher can be more vulnerable to which of the following if the same key is reused?
Replay attacks
Frequency analysis
Key collision attacks
Two-time pad attack
The avalanche effect in block ciphers ensures:
Minor key changes produce identical ciphertexts
Small plaintext changes drastically alter ciphertext
Large plaintext changes leave ciphertext mostly unchanged
Key length does not affect ciphertext properties
Which of the following block cipher algorithms uses a Feistel network structure?
AES
RC4
DES
ChaCha20
In stream ciphers, the keystream is generated:
By XORing the plaintext with a fixed key directly
From a pseudorandom sequence generator seeded with the key
Using public key algorithms for each bit
By dividing the plaintext into fixed-size blocks
Which of the following is a disadvantage of block ciphers compared to stream ciphers?
Inability to encrypt large messages
Higher error propagation
Lower throughput for real-time applications
Lack of diffusion property
Which property of stream ciphers makes them preferable in certain real-time systems over block ciphers?
Block-wise data encryption
Lower error propagation
Higher computational complexity
Requirement for padding schemes
