Let (E,D) be a semantically secure cipher defined over (K,M, C), where M = C = {0,1 } L Which of the following encryption algorithms yields a semantically secure scheme? Either give an attack or provide a security proof via an explicit reduction.

(a) E'(k ,m)=0E(k ,m)

(b) E'(k ,m)=E(k ,m)parity (m)

(c) E'(k ,m)=reverse (E(k ,m))

(d) E'(k ,m)=E(k ,reverse (m))

Here, denotes concatenation, and for a bit string s, parity(s) is 1 if the number of 1s in s is odd, and 0 otherwise; also, reverse(s) is the string obtained by reversing the order of the bits in s, e.g., reverse(1011) = 1101.