Consider the Davies and Price hash code scheme described in section 11.4 and assume DES is used as the encryption algorithm: Hi = Hi-1 xor E(Mi, Hi-1) Recall the complementarity property of DES (problem 3.14): If Y = E(K, X), then Y? = E(K?, X?). Use this property to show how a message consisting of blocks M1, M2, ,MN can be altered without altering its hash code. b. Show that a similar attack will succeed against the scheme proposed in [MEYE88]: Hi = Mi xor E(Hi-1, Mi)