Let N >1 be any integer. Shift cipher mod N is an encryption scheme which works as follows. The key space of this encryption scheme is KZv, so key k is a random element in Zx The message space are any bitstrings, encoded base-N, i.e. the message m is interpreted as m(m.mo)N, where ma mo are all elements of Zv, i.e. they are digits base N.1 The encryption E and decryption D algorithms are as follows: If c(n-1..cico)N then D(k, c)(m1..mmo)N , where mi i k mod N An encryption is perfectly secret on message space M and ciphertext space C if it is the case that for every ciphertext c E C and every message m E M there exists exactly one key k E K st. c = E(k, m). (This is not a necessary condition for perfect secrecy to hold, but it is a sufficient one.2) Answer the following questions