Observed arrival · 2026-09-14
The Doubled Key: An Enigma Challenge
A historically framed Enigma decryption puzzle with an intercepted message, machine settings, procedural instructions, hint, and revealed solution.
Field notes
The challenge supplies a full pre-1940 Army Enigma setup: rotor order III-I-II, ring settings 06 11 18, reflector B, and a specified plugboard. Solvers first use the clear-text starting position HRK to decode WQPDIF as the repeated key NBWNBW, then decrypt the weather report. The page also records period message-preparation rules, including the substitution of q for ch and XX padding, and connects the puzzle to the historical weakness that led to the procedure being dropped on 1 May 1940.
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Editorial observations of this landing page, not a rating.
One card from the complete issue