Part (b) - Break CCA Let F : {0,1}" x {0,1}" + {0,1}" be a secure PRP (key, input and output size are all n bits). Consider the following encryption scheme: Gen(1"): Output a key k = (ki, k2) which consists of two parts: k1, k2 both of size n bits selected uniformly at random from {0, 1}" Enc((ki, k2), m) : Pick r uniformly at random from {0, 1}" Set a= Fki (r) Set b = Fki (remoka) Return c= 1. Write down the decryption algorithm. 2. Prove that the scheme is NOT CCA secure (design a successful adversary and compute its success probability). Part (b) - Break CCA Let F : {0,1}" x {0,1}" + {0,1}" be a secure PRP (key, input and output size are all n bits). Consider the following encryption scheme: Gen(1"): Output a key k = (ki, k2) which consists of two parts: k1, k2 both of size n bits selected uniformly at random from {0, 1}" Enc((ki, k2), m) : Pick r uniformly at random from {0, 1}" Set a= Fki (r) Set b = Fki (remoka) Return c= 1. Write down the decryption algorithm. 2. Prove that the scheme is NOT CCA secure (design a successful adversary and compute its success probability)