Cryptology Rearranging the Columns of a Periodic Polyalphabetic Cipher

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The question whether the method of rearranging the columns works for a certain polyalphabetic cipher heavily depends on the nature of the primary and secondary alphabets. The analysis is by mathematical methods. The main results are:

• The method works for a cipher disk as soon as the primary alphabet is known. For then the secondary alphabets are known and are shifted versions of the primary alphabet.
• The method worked in Section 7 by the happy circumstance that the primary alphabet turned out to be a slightly modified (by a decimation process) standard alphabet.