Re: VMs: Sukhotin's Algorithm

[Bruce Grant <bgrant@xxxxxxxxxxxxx>]

In addition to Jacque's article in Cryptologia, which explains the
Sukhotin algorithm nicely, I ran across a couple other interesting
articles there about other approaches to detecting vowels:

1.    An article from vol. 8 no. 1 (1984) by Roland Anderson, Finding
Vowels in Simple Substitution Ciphers by Computer, uses a technique based
on plotting the frequencies of interval lengths between occurrences of the
same letter or group of letters. The idea is that such a curve will
decrease smoothly as the interval sizes get larger for consonants, but
will have a peak for vowels. (There was a second article, in 1986 I think,
elaborating this approach.)

2.    An article by Caxton Foster (didn't write down the date) tries to
identify vowels based on the claim that they tend to be more evenly
distributed than consonants when a message is chopped into equal-sized
blocks. (This is a modification of a technique used to guess the likely
rectangle dimensions for a transposition cipher according to Foster.)

3.    Another article by Foster in vol. 16 no. 3 compares the preceding
method, Sukhotin's algorithm and a third method described in Helen Gaines
_Cryptanalysis_ based on identifying as consonants letters which have few
neighbors, then identifying as vowels letters which appear close to and
evenly distributed around these "consonants" - he calls it the "consonant
line" approach.

Bruce

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