The Codebreakers (D. Khan - historian)

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15' Substitute ciphers (monoalphabet)
17' Polyalphabet ciphers
19' Enigma 
    -description
     Rotors had over 17.000 positions, 
     permuting rotors, 
     can choose out of 8 rotors
     1000's of Enigmas
    Fridman, Cryptoanalyst Frank Rowet, Captain Roger Pineau,...
23' Purple (Japan 1938)
26' Seiko multiple meaning
30' Breaking Purple
31' Japanesse spy at Hitler
32' 1941, Pearl Harbor - Hawaii
33' 10.000 of intercepted messages
34'  1200 decrypted messages - Japan was preparing for war
35' declaration of war with Japan
36' JN25 (1 time pad)
37' Coral Sea (Lexington and Yorktown)
38' Shokaku, Lexington
39' Admiral Jamamoto and Admiral Nimits
40' Midway - short on water
41' Preparations for the Head on attack at Midway
43' American dive bombers (decisive 4 minutes - Japanesse lost 4 carriers)
44' Atlantic - German U-boats
45' 1942 U-boats were gaining the upper hand
    Enigma - 100's of alays 
46' Bleatchly park, Arthur Levenson
47' Alan Turing, Gordan Welshman (1000's of intersepts)
48' Henrry ???, wether ship - David Blame?
49' Enigma captured, February 1943, fourth rotor
50' decoding machines in USA, teenager ..., 3 shifts
51' chapel - top secrets 
52' if you talk ... you will be shot, 
    cooperation between USA and GB (no hardwire, but intimate)
54' War was shortened
55' Purple recovered in Berlin