Suppose that X = (x1, . . . , xn ) and X = (x1, . . . , xn ) are two sequences of n plaintext blocks. Lets suppose X and X are encrypted in OFB mode using the same key and the same IV. Show mathematically (with explanation) how an adversary can compute X X. Under what conditions in CBC mode can an adversary also potentially compute xi xj utilizing just the ciphertext they see? State this condition and show it mathematically (with explanation).