Tutte's Statistical Method
The basis of the method that the Heath Robinson machine implemented was Bill Tutte's "1+2 technique". This involved examining two of the five impulses from the characters of the ciphertext tape and combining them with the same two impulses of part of the key as generated by the chi wheels of the Lorenz machine. This involved reading two long loops of paper tape, one containing the ciphertext and the other the chi component of the key. By making the effective lengths of the two tapes co-prime with each other, all possible start positions of the key sequence were tried, and counts made.
Read more about this topic: Heath Robinson (codebreaking Machine)
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“Methinks the human method of expression by sound of tongue is very elementary, & ought to be substituted for some ingenious invention which should be able to give vent to at least six coherent sentences at once.”
—Virginia Woolf (1882–1941)