1. Cryptography in WWII Explanation of the German Enigma Machine
Allied cryptanalytic techniques
Turing’s Contributions
The effect of cryptanalysis

2. The Enigma Machine’s Construction

3. Complexity of the Enigma
60 wheel orders
17,576 settings per wheel
1.5x104 stecker pairings
1.59x1020 setup combinations
16,700 different wheel settings

4. Sending a Message
Sender sets up wheels, pairs, and initial setting according to key secret to Germans
Sender sends a public key
Sender codes and transmits message in 5 character segments
Receiver sets up his machine according to secret key and public key
Receiver decodes message

5. Allied Cryptanalytic Techniques
What doesn’t work…
Analyzing the machine’s two biggest weaknesses
Exploiting human error

6. Using a Crib
The Germans began each message with a standard phrase or used phrases such as Keine besondere Ereignisse when there was nothing to report
KEIN EBESO NDERE EREIG NISSE
GEGOH JYDPO MQNJC OSGAH LEIHY SOPJS MIUKK

7. Other User Errors
Laziness in initial wheel setting Not moving wheels very far Not using random initial setting
Sending foolish dummy messages
“Kisses”

8. Alan Turing’s contributions
Turing devised and used machines called “Bombes” to take a known crib and cycle through various Enigma settings to see if a given message and setting produced the crib

9. The effects of code-breaking
Diverting traffic from U-boat locations
Intelligence regarding German battle tactics bent-beam troop strength and positions