Cryptography Unit 2: Symmetric Key Algorithms and AES 2.1 Quiz

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What operation is used to combine the plaintext with the key stream in RC4 encryption?

Multiplication

Bit-wise exclusive OR (correct)

Addition

Subtraction

What is used to generate the key stream in RC4 encryption?

Systematic multiplication

Pseudo-random generating technique (correct)

Exclusive AND operation

Bit shifting

Which organization banned the usage of RC4 in TLS protocols in 2015?

National Aeronautics and Space Administration (NASA)

United Nations Educational, Scientific and Cultural Organization (UNESCO)

World Health Organization (WHO)

Internet Engineering Task Force (IETF) (correct)

What additional investigation is required before implementing new systems using RC4?

Security analysis Signup and view all the answers

What is RC4A+ in relation to the basic RC4 algorithm?

A more complex version with a longer key schedule Signup and view all the answers

What type of attack can be carried out if RC4 encryption is not used with a robust MAC?

Bit-flipping attack Signup and view all the answers

How is authentication handled in RC4 stream ciphers?

Authentication is not possible using RC4 stream ciphers. Signup and view all the answers

According to the text, what size range can the variable-length key have when initializing RC4?

Between 1 and 256 bytes Signup and view all the answers

What is a key characteristic of symmetric key algorithms?

The sender and receiver must share the same secret key Signup and view all the answers

Why are symmetric key algorithms considered faster and more efficient?

They require less computation compared to asymmetric key algorithms Signup and view all the answers

In symmetric key algorithms, what happens if the sender and receiver do not share the secret key?

The message cannot be decrypted Signup and view all the answers

What distinguishes symmetric key algorithms from asymmetric key algorithms in terms of security?

They are considered less secure Signup and view all the answers

Which aspect of symmetric key algorithms makes them suitable for internet communication?

Fast encryption and decryption capabilities Signup and view all the answers

What is one of the weaknesses found in DES in the last few years?

Vulnerability to weak keys Signup and view all the answers

What property of DES is responsible for a small change in plaintext causing a significant change in ciphertext?

Avalanche effect Signup and view all the answers

What is the significant difference between DES and IDEA regarding key length?

DES uses 56-bit keys, while IDEA uses 128-bit keys Signup and view all the answers

In IDEA, what is the purpose of the XOR operations in each round?

To introduce non-linearity Signup and view all the answers

What happens during the output transformation step in IDEA after all rounds?

Four sub-blocks are formed Signup and view all the answers

What factor determines the cryptographic strength of a symmetric key algorithm related to the size of the key used?

Key size Signup and view all the answers

Which type of symmetric key algorithm is known for its efficiency and ease of implementation due to being based on a structure called a Feistel network?

Feistel ciphers Signup and view all the answers

What characteristic distinguishes stream ciphers from block ciphers in terms of their encryption process?

Faster and more efficient operation Signup and view all the answers

Which factor contributes to the cryptographic strength of a symmetric key algorithm by increasing the number of times encryption and decryption processes are repeated?

Number of rounds Signup and view all the answers

What is a major drawback associated with symmetric key algorithms as compared to asymmetric key algorithms?

Need for sharing secret keys Signup and view all the answers

What is a characteristic of a block cipher?

Ensures the same plaintext block encrypts to different ciphertext with the same key. Signup and view all the answers

In Cipher Block Chaining (CBC) mode, what does the encryption scheme involve?

XORing the plaintext with the prior ciphertext block prior to encryption. Signup and view all the answers

What is a distinguishing feature of Output Feedback (OFB) mode in block ciphers?

Employs an internal feedback structure independent of plaintext. Signup and view all the answers

What is a key characteristic of DES (Data Encryption Standard)?

Uses 8 bits of the key for check bits. Signup and view all the answers

What does the DES function apply to produce a 32-bit output?

Expansion Permutation Box Signup and view all the answers

What is the size of the key used in IDEA encryption?

128 bits Signup and view all the answers

How many rounds are there in the IDEA encryption process?

8 rounds Signup and view all the answers

In IDEA encryption, what happens in the final step before producing the output?

Four sub-keys (K49 to K52) are used in an output transformation Signup and view all the answers

What is the significance of circular left shifts in generating sub-keys for different rounds in IDEA encryption?

They help in mixing and shuffling the key bits effectively Signup and view all the answers

Which operation is NOT utilized in the rounds of IDEA encryption?

Bitwise OR operation Signup and view all the answers

What type of operation is used to combine the plaintext with the key stream in RC4 encryption?

Bitwise XOR Signup and view all the answers

Which organization recommended limiting the use of RC4 encryption due to threat vulnerabilities?

Microsoft Signup and view all the answers

What is a notable drawback identified in using RC4 stream ciphers?

Inability to operate with small data streams Signup and view all the answers

What is the purpose of the Key-Scheduling Algorithm (KSA) in RC4 encryption?

Generate the permutation of 256 available bytes Signup and view all the answers

What is the most significant advantage of using RC4 stream ciphers?

Simplicity in construction and ease of use Signup and view all the answers