Chapter 8 1. Suppose the following was presented as the plaintext/ciphertext generated by an Enigma machine. Could the claim be true? Explain why or why not.
8. In Simon Singh’s The Code Book, he gives an example of what we called the permutation product AD.5 It’s presented in a different format, but is equivalent to
AD = (AFW)(BQZKVELRI)(CHGOYDP)(JMXSTNU). What is wrong with this example?
9. In calculating the number of ways an Enigma plugboard can be wired, the identity
(2p – 1) (2p – 3) (2p – 5)(1) =
was used. Prove that this is true.
10. In some systems, enciphering a message twice with distinct keys is no different than enciphering once with some other (single) key. This is the case for any monoalphabetic substitution ciphers, Vigenere ciphers, matrix encryption, and more. Is it the case for Enigma?
11. Is there a way to distinguish messages that have been enciphered twice with Enigma (using two different keys) from messages that have only been enciphered once?