Enigma Machine Presentation Notes

Introduction

• Story of the Enigma machine and its significance during WWII.
• The Enigma machine was used by Nazi Germany to send secret coded messages.
• Presentation includes an original Enigma machine from 1936, owned by Simon Singh.

Background of the Enigma Machine

• Found in a French field by an American cryptographer after WWII.
• Simon Singh acquired it after the cryptographer's death.

How the Enigma Machine Works

Code Generation

• Demonstration of encoding a message using the Enigma machine.
• Example:
  • Input: 'N' → Output: 'Y'
  • Input: 'U' → Output: 'T'
  • Input: 'M' → Output: 'H'
  • Input: 'B' → Output: ?
  • Input: 'E' → Output: 'W'
• Unique feature: Same letter can encode to different letters (e.g., 'E' to 'Y' and 'W').

Machine Mechanics

• The machine consists of three rotors that dictate the code changes.
• As a letter is pressed, rotors move, creating a new electrical circuit and changing outputs.
• The mechanism is compared to clock hands (fast, middle, slow).

Decoding Process

• Required settings known as "combination lock" with numbers visible in windows.
• Example settings noted: 13, 9, and 21.
• The coding message is transmitted via Morse code by a radio operator.

Rotor Configuration

• Rotor Selection:
  • 5 rotors available but only 3 used.
  • Calculated combinations: 5 × 4 × 3 = 60 ways to choose.
• Starting Positions:
  • Each rotor has 26 starting positions leading to 26³ = 17,576 combinations.

Plugboard Functionality

• Military Enigma had a plugboard for additional scrambling, allowing connection of letter pairs.
• Ten wires connect two letters together, offering more complexity.
• Total configurations calculated as follows:
  • Factorials: 26! divided by (6! × 10! × 2¹⁰) results in 150 trillion combinations.
  • Total combinations for an army Enigma machine: 158 quintillion, 962 quadrillion, 555 trillion, 217 billion, 826 million.

Communication and Code Sheets

• Code sheets were crucial for setting the Enigma machine for daily use.
• Each officer needed the same settings to decode messages correctly.
• Monthly sheets provided settings for each day, ensuring security.
• Navy used soluble ink for code books to prevent capture.

Conclusion

• Possession of the Enigma machine and code sheets would allow full decoding of German messages.
• The challenge was obtaining the code sheets; breaking the code required mathematical analysis.

Flaws in Enigma

• Despite its complexity, the Enigma machine had flaws that made it breakable.
• Further exploration of these weaknesses highlighted in the presentation.