I'm reading a recently-published and very interesting history of cryptography by Simon Singh entitled "The Code Book" (Anchor Books, ISBN 0-385-49352-3, $14 paperback.) One of first chapters covers a virtually impregnable polyalphabetic substitution cipher that was invented in the 16th century by Blaise de Vigenere--has anyone considered possibility that the VMS is enciphered using the Vigenere system?
Singh does a much better job of explaining this cipher, but basically an alphabet is written on consecutive lines, one on top of the other, for as many times as there are letters in the alphabet. Each copy of the alphabet, however, is shifted by one place, so that the first letter that appears at the beginning of each line is different, like this:
A keyword, such as WHITE, is then copied repeatedly above the top alphabet, like this:
To encipher a word, each of its letters is located in the top alphabet and correlated with whichever letter of the keyword lies above it. That letter of the keyword in turn prescribes the exact copy of the alphabet below, so that if the word BIRD is being enciphered, the letter B of BIRD is associated with the letter H of WHITE (B is the second letter of the top alphabet--the "base" alphabet, as it were--and the letter H of the word WHITE appears above it.) This in turn specifies the alphabet row beginning with H for the substitution. The second letter of the H alphabet is G, so the letter G is substituted for the letter B of BIRD.
The advantage of this cipher is that it renders letter frequency analysis useless, because frequently-appearing letters in the original text will be enciphered with different letters throughout the encryption.
This system would allow the space character to be enciphered as well, so the apparent word breaks in the VMS may not be spaces between words at all.
Charles Babbage was the first to discover a method of cracking a Vigenere cipher (I won't go into that here--read the Singh book for the surprising method.)
Has anyone approached the VMS from this standpoint?