give hints. Problem 1.5, 15 points. Let E:{0,1} x {0,1} {0,1}' be a block cipher. Consider the following symmetric encryption scheme SE ({0,1}", E, D), whose message space is the set of messages whose length is multiple of l bits and whose encryption and decryption algorithms are defined for each K {0,1}* as follows: Algorithm EK(M) Algorithm DK(C) Break M into l-bit blocks: M || . ||M Break C into l-bit blocks: IV ${0,1,..., 2'-1} IV ||C || ... ||C. For i=1, For i=1,..., n do C;+ Ek((IV + i) e M.) M;+ Ex'(C:) (IV +i) End For EndFor Return IV||Cill... ||Cm Return Mill... || M. n do Above "+" denotes addition modulo 2' and () denotes the binary representation of integer j as l-bit string. Show that Se is not IND-CPA secure, regardless of how secure E is. Hint. The advantage of your adversary doesn't have to be 1. INEN