Alan Turing Bombe Crib Analysis Simulator

Interactive simulation of Alan Turing's Bombe electromechanical machine used at Bletchley Park to break Enigma rotor keys.

Deep-Dive Educational Guide

The Turing Bombe: Crib Graphs, Welchman's Diagonal Board & Deductive Contradiction

An exhaustive academic breakdown of the electromechanical Turing Bombe: Alan Turing and Gordon Welchman's Bletchley Park cryptanalysis of Enigma, menu graph theory, the Diagonal Board involution theorem, and runnable Python crib solvers.

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How to Use Alan Turing Bombe Crib Analysis Simulator

  1. Enter Ciphertext & Plaintext Crib: Input intercepted German ciphertext and a suspected German plaintext phrase (the crib).
  2. Configure Menu Graph Connections: The machine maps closed loops of deductions linking ciphertext letters to crib letters.
  3. Run Turing-Welchman Contradiction Engine: Electromechanical drums test rotor positions simultaneously, halting on candidate daily keys with zero contradictions.

Frequently Asked Questions

How did the Turing Bombe break Enigma without testing all keys?

Instead of searching for correct keys, the Bombe searched for logical contradictions. If a hypothesized letter deduction led to a contradiction, that entire branch of rotor positions was rejected simultaneously.