2. Cipher Block Chaining (CBC)

a. Sketch the flows for two successive CBC decryptions, with ciphertexts 1, 2 and plaintexts 1, 2.

b. Write the formula that links the plaintext 2 with the ciphertexts 2 and 1:: 2 = ........................ c. If he ciphertext blocks: 1, 2, we have 1 = 2, then what can you say about the corresponding plaintexts 1 , 2? d. If in CBC there is a 1-bit error in the ciphertext 1 then the decrypted plaintext 1, 2 are obviously corrupted. Are any blocks beyond 2 corrupted (assuming no more bits are corrupted)?