Select the parameters of a symmetric block cipher for greater security. (Select ALL correct answers below)

Multiple processing round

Larger block size

Great complexity in round function

Larger key size

Alice encrypted two messages M1 and M2 into C1 and C2 using AES, and sent them to Bob separately. M1 and M2 are identical with 80 bytes except different data for the 19th byte. Unfortunately, Darth had learnt M1 and C1, and also eavesdropped C2 in the same order as message M2 encrypted in blocks. If Darth can also guess out the cipher block mode that Alice used for these messages, which information can he determine? (Hints: select TWO for each question below for AES with a block length of 128 bits.)

Question 3

Assuming AES-CBC (Cipher Block Chaining) mode, if Alice used the same IV when she encrypted the two messages, then Darth can determine

M2 contains 80 bytes.

M2 is less than or equal to 80 bytes long but not the exact length.

The plaintext for only the first block of M2.

The entire plaintext for M2.