This document discusses Alan Turing and his contributions to cryptography including developing the bombe machine which helped crack the German Enigma code during World War 2. It provides biographical details on Turing such as his birth year, work developing the first bombe in 1940, and later chemical castration due to his homosexuality. It also describes the Enigma machine used by Germans for encryption, how it worked, and some of the techniques used by Turing and others to crack the codes including finding common words or phrases in messages.

1. The Imitation Game and
Cryptography
Anry Lu (2015-03-18)

2. 雷

3. Alan Turing

4. Alan Turing
● 1912 - born
● 1940 - 1st bombe
● 1952 - chemical castration due to
homosexual
● 1954 - death because of cyanide poisoning
● 2009 - apology from Prime Minister
● 2013 - pardon from Queen Elizabeth II

5. Enigma Machine

6. Enigma Simulator
http://enigmaco.de/enigma/enigma.html

8. Initial Setup (crypt key)
● Choice of rotors
● Initial position of rotors
● Plugboard connections
● Indicator
● 3-rotor with 10-pair plugboard wire
o rotor choice: 5*4*3
o initial position: 26*26*26
o plugboard: 26!/(6!*10!*210)
o total: 159*(1018)

9. How to Crack
● A letter would never become itself
● Finding Crib:
o WETTERBERICHT
o HEIL HITLER

11. Bomde

12. Modern Secure Communication - TLS

13. Reference
● http://en.wikipedia.org/wiki/Alan_Turing
● http://en.wikipedia.org/wiki/Enigma_mach
ine
● http://en.wikipedia.org/wiki/Bombe
● http://tehgeektive.com/2013/01/18/the-
enigma-machine-had-
158962555217826360000-configurations-
but-it-had-a-flaw/