Suppose I use a monoalphabetic substitution cipher (MSC) for which the plaintext alphabet is the set of English characters and the ciphertext alphabet is a subset of the possible 2-digit numbers. After encrypting the following plaintext: hooray chiefs boo titans get the following ciphertext: 07 19 19 75 36 91 18 07 23 51 88 46 67 19 55 41 23 41 36 29 46 Which of the following statements is true? My MSC must include at least one dowbleth My MSC must include at least one null My MSC must include at least one dowbleth and one null My MSC must have been augmented with a code (i.e., to create a Nomenclator) None of the first four answers is true; I could have used an ordinary MSC Suppose we have a Caesar shift cipher that shifts the English alphabet by N places, and a plaintext to apply it to. Which of the following is true? (Select the most complete answer.) if N is even, applying the cipher 13 times -- each time to the output of the last time -- will always recover the plaintext again. Olf Nis odd, applying the cipher repeatedly -- each time to the output of the last time -- will never recover the plaintext again. No matter what N is, applying the cipher 26 times -- each time to the output of the last time -- will always recover the plaintext again. Answers (a) and (b) are both true. Answers (a) and (c) are both true