CYB 210 module 5| 52 Questions all 100% Solved Correct

CYB 210 module 5| 52 Questions all
100% Solved Correct
What does "KS" stand for in stream ciphers - ✔✔Keystream
What does "⊕" stand for in stream ciphers - ✔✔XOR



What does "P" stand for in stream ciphers - ✔✔Plaintext



What does "C" stand for in stream ciphers - ✔✔Ciphertext



• If we used key K1 and nonce N1 to encrypt a message, we can use either...

• Same key K1 and different nonce N 2or

• Different key K2 and same nonce N1or

• Different key K2 and different nonce N2



BUT NEVER: - ✔✔• Same key and same nonce

, Two Types of Stream Ciphers - ✔✔• Stateful stream cipher

• Counter-based stream cipher



• Cipher initializes the state from key and nonce

• Secret internal state evolves throughout the key stream generation

• Update function updates state value and produces one or more key stream bits from state

• RC4 utilizes this method - ✔✔Stateful Stream Cipher



• Produces chunks of key stream from key, nonce, and counter value

• No secret state - ✔✔Counter-Based Stream Cipher



• Application-Specific Integrated Circuits (ASICs), Programmable Logics Devices(PLDs), and field-
programmable gate arrays (FPGAs).

• Dedicated hardware implements cryptographic algorithm at bit-level

• Hardware cannot be used for anything else - ✔✔Hardware-oriented



• Instructs microprocessor what instructions to execute algorithm

• Works with bytes or words with mathematical operations.

• Bytes or words are typically 32 or 64 bits. - ✔✔Software-Oriented



Historically, stream ciphers were commonly used with ___________ ______________ due to being
cheaper than block ciphers.

• Stream ciphers needed less memory and logic gates than block ciphers -
✔✔hardware implementations



Currently, _____ ____________ are not more expensive than stream ciphers on hardware - ✔✔Block
ciphers



_____ are an array of bits equipped with update feedback function - ✔✔FSRs