DES & AES in Cryptography

What is the purpose of the ShiftRows step in AES?

• Substitution

• Permutation to provide diffusion

• XOR operation with the key

• Key expansion

Which AES operation is responsible for confusion?

• AddRoundKey

• MixColumns

• SubBytes

• ShiftRows

Which mode of AES is used for secure communication over networks?

• ECB (Electronic Codebook)

• CBC (Cipher Block Chaining)

• CFB (Cipher Feedback)

• OFB (Output Feedback)

Which of the following is NOT a valid AES key size?

• 128-bit

• 192-bit

• 256-bit

• 512-bit

In AES, the AddRoundKey step involves which operation?

• XOR with the round key

• Bitwise AND with the key

• Multiplication in Galois field

• Circular shifting

Which type of attack is DES most vulnerable to due to its short key length?

• Brute force attack

• Side-channel attack

• Man-in-the-middle attack

• Frequency analysis

What is the purpose of the initial permutation (IP) in DES?

• Strengthen encryption

• Introduce non-linearity

• Rearrange bits for diffusion

• Expand the key size

What is the purpose of the Expansion (E) function in DES?

• Increases block size from 32 to 48 bits

• Increases key size

• Performs XOR with the round key

• Substitutes input with S-boxes

Which of the following is a limitation of DES?

• High computational complexity

• Small block size

• Lack of Feistel structure

• No key expansion

Which algorithm was developed as a successor to DES?

• RSA

• Blowfish

• AES

• SHA-256