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Double Transposition Cipher Solution
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Normally the keys would be numbered like this:

	    11           1   1 1
	81520194673     327811504692
	MAHATUNDILA     CULLATINDILA

However, Agent Madeleine numbered the duplicate A's and L's from right to left instead of from left to right, so it would be the equivalent of replacing the keys with MCHBTUNDILA and CUMLBTJNDIKA, then doing the normal double transposition. Taking columns in the wrong order was such a common mistake that it had a name - "hatting." The plaintext of the message is:

	FOUND SHELTER WITH CHILDHOOD FRIEND IN SURESNES STOP
	TRANSMITTING FROM HOME OF VAUDEVIRE STOP
	WILL MEET WITH BERTRAND TO DISCUSS SCHEDULES 
	AND COORDINATE TRANSMISSIONS FROM SURVIVING AGENTS STOP
	PLEASE SUPPLY DEscriptION OF BERTRAND END MESSAGE

While the plaintext appears almost banal, in fact agents in occupied France were in continual grave danger, and a botched communication or one that did not get a useful response in time could be fatal.

Agent Madeleine was Noor Inayat Khan, an author and FANY. (A FANY was typically a young woman in the Field Auxiliary Nursing Yeomanry, the work force tapped when someone needed some bright young people who were unsuitable for combat positions.) Madeleine survived longer than the rest of her cell, and for a time was the only free British-controlled wireless operator in Paris. Although contacting previous acquaintances was against regulations, she had little choice, and some of her friends did in fact put her up in Suresnes. Her duress code was to use a double transposition key with precisely 18 letters, so we know this message was not sent under duress. Her meeting with Bertrand led to her capture: The real Bertrand had already been caught, and she met a phony Bertrand and unwittingly gave away some useful information before she was taken into custody. The Nazis forced her to continue sending for a time, and the first message she sent had a key of precisely 18 letters. I invented this message to try to get her a warning in time and change history. Ah, well. She was an excellent coder and probably would not have made the errors shown here; however, many operators, such as the Norsk Hydro informant Einar Skinnarland, made horrendous blunders frequently, and both Leo Marks, head of the coding section for the Special Operations Executive, and the Coders of Grendon, one of a number of code sending and receiving crews trained by Marks, tore their hair out over them.

For more background see Between Silk and Cyanide: A Codemaker's War 1941-1945 by Leo Marks (Free Press, 1999), and Set Europe Ablaze by E. H. Cookridge (Thomas Y. Crowell, 1967).

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