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CYB 210 module 5| 52 Questions all 100% Solved Correct
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CYB 210 module 5| 52 Questions all100% 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
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