1. What Was the Purple Cipher?
Chris Christensen
Northern Kentucky University

2. The Damm Machine

3. Damm Half-Rotor
Konheim Computer Security and Cryptography

4. Half-Rotor Table

5. Red Machine

6. Romaji

7. 6s and 20s

8. 6s and 20s

9. Captured Red Machine
daderot

10. Red Machine Will Be Replaced
December 1938 message in Red Machine cipher authorized a man named Okamoto to put new cipher machines into service. The new machine Type B would go into use on 20 February February 1939 message from Warsaw to Tokyo having an indicator different from Red.

11. Purple Machine
1938
I regard the Japanese “Purple” machine and the underlying system to have been by far the most difficult cryptanalytic problem successfully handled and solved by any signal intelligence organization in the world … .” William Friedman 27 September 1943

12. What is the Purple cipher?

13. Type B (Purple) is a Modification of Type A (Red).
Assumption
Type B (Purple) is a Modification of Type A (Red).

14. Are there 6s and 20s?

15. 6s and 20s

16. 6s and 20s
April 1939: The sixes could be deciphered. 25 unique starting positions for messages. 25 alphabets for the 6s. There were no relationships between consecutive alphabets – as there would be for a half-rotor.

17. The 6s

18. Telephone Stepping Switches

19. Stepping Switch for 6s

20. Telephone Stepping Switches

21. What about the 20s?

22. Composed Ciphers

23. 2:00 pm on 20 September 1940

24. Example One

25. Example Two

26. Example Three

27. Wiper Tables

28. Purple
FMS FSM MFS MSF SFM SMF

29. Purple Analog
Mark Pelligrini

30. Purple