3. [6 Points] Let X' be the bitwise complement of X. Prove that if the complement of the plaintext block is taken and the complement of an encryption key is taken, then the result of DES encryption with these values is the complement of the original ciphertext. That is, if Y- E(K, X), then Y - E(K', X). Hint: Beign by shoing that for any two bit strings of equal length, A and B, (A B) A'B