Re: Z340 Kasiski Examination
O.k., I will put something together hopefully within days, maybe a little more.
Discussion About the Zodiac killer
http://www.zodiackillersite.com/
16,15,14,13,12,11,10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0,
32,31,30,29,28,27,26,25,24,23,22,21,20,19,18, 4,17,
40, 0,39,21,12,32,20,25,14,38,37,18,36,35,34,33,19,
15,30, 2,18,18,22, 4,44, 7,29,43, 5, 6,42, 4, 4,41,
53, 9,52,51,18, 8,50,49,10,16,48,47,39,18,36,46,45,
20,24,15, 3,50, 9,55,16,29,54,22, 5,50, 6, 2,43, 4,
10,12,39,27, 7,14,58,35,37,15,57,23,56,30,18,49,21,
46,12,59,18,39,26,17,45,18,22,21,48,31,40,15,14,20,
30,52,62,61,33,35,19,50,15, 2,38,18,60,18,36,28,16,
54,33,19,50,28,42, 4,22,18,40, 6,18, 7,37, 5,39,54,
22,30,36,13,60, 4,19,26,24,10, 1,47,49,53, 2,18,37,
50,19,51,18,27,36,52,13,49,29,10,40, 2, 5,35,28,15,
2,43,57,20,35,19,50,49,10,17,18,21,33,41,46,62,39,
18,18,47,52, 7,35,27,60,52,15,49,31, 6,17,50,14, 5,
18,54,49,38,37, 7, 3, 1,55,46,52,34,29,11,58,19,33,
15,14,56,36,31,27, 6, 4,22,20,30,19,39,44,27,35,10,
12,32,10,19,25, 5,50,18,28,55,62,11,12,18,13,35, 2,
4,32,20,53,13, 0,41,22, 8,35,25,39,55,25,32,18,18,
35,55,54,29,19,22,26,45,19,47,42,28,25,16, 9,50,10,
18,57,30,10,61,43,22,38,39,41, 9, 4,17, 0,24,36, 3
Glen wrote:Bert,
I actually did look at repetition rates among many other things, and if you’ll check my old posts you’ll see that I’ve been arguing for awhile that there are very few differences between the 408 and 340-ciphers. Your illustration is a very good one and a very good addition to the already overwhelming evidence that the 340 is probably a homophonic cipher or some variant.
-----------------------------------
By rows
408-cipher: 7% = 27 reps /(24*17)
340-cipher: 6% = 19 reps /(20*17)
By columns
408-cipher: 17% = 71 reps /(17*24)
340-cipher: 16% = 55 reps /(17*20)
-----------------------------------
Your figures above are accurate, and you’ll notice that in every measure of repetition the 340 cipher rates lower than the 408. The extra characters don’t add the extra necessary to make up the diffenerence either. Something is causing this, and as you’ve stated, transposition makes no difference in the counts, so it must be something else.
Every check I’ve made for transposition comes up negative, which is disturbing in light of all the other evidence that makes this an unsolved homophonic substitution cipher. Group repetitions and characters at distances all appear to be linear and written left to right. I’ll make a chart of percentages on these figures compared to the 408 and post it.
Behavior(1): *Within* each cipher, the rep rate in rows is
notably less than the rep rate in columns (6-7% << 16-17%).
Behavior(1) is consistent with homophonic substitution,
possibly combined with transpositions of some kind.
(The transpositions would have no affect on the rep rates).
It would be a natural consequence of deliberately suppressing
(on avg) the short-term repetition of characters at the time
the ciphertext substitutions are being made. This would
reduce the row rates but would have much less affect on
column rates, which depend on column alignments that are not
likely to be controlled. On the other hand, isn't this
behavior very unlikely with just about any other substitution
scheme (e.g. polyalphabetic)?
Unlikely with a textbook polyalphabetic, but try a low-level polyalphabetic using the keyword “Abracadabra” for instance. It generates roughly the same statistics as a homophonic substitution cipher, especially in conjunction with randomly selected character alphabets. Too tricky for Zodiac? Not if you consider using the repetition “slavesslavesslaves” or something similar. This was the angle of my investigation into polyalphabetics in the 340. Unfortunately the statistics nixed the idea just about as soon as I came up with it!
Behavior(2): *Between* ciphers, the rep rates are practically
the same, by row (6% ~= 7%) and by column (16% ~= 17%).
Behavior(2) seems to strongly indicate that the type of
substitution scheme used in the 408-cipher, i.e. homophonic,
was used again in the 340-cipher. (And again this behavior
would not be affected by combining the substitution with
transpositions. Also, it seems to me that the addition of
some transpositions would be sufficient to account for the
fact that the 340-cipher has not yet been solved.)
Doesn't it seem likely that the rep rates would have changed
significantly by any fundamental change in the substitution
scheme (e.g. switching from homophonic to polyalphabetic)?
In a "Paradice Slaves" thread, you mention some results of
chi^2 & IoC tests performed on the 340-cipher alone. It might
be interesting to see how those compare *between* the two
ciphers.
I’ve run the IoC tests on both ciphers and there is nothing to compare the two against. The 408 has random peaks as a result of the language used, while there are some lower peaks in the 340, none matching each other. The 340 has an extremely high peak at 78 (13x6, 26x3) which I am checking out through other means (still only 5.5%, but much closer to 6.8 than any peak in the 408). It might be of some significance if we figure the Paradice Slaves cross to be of 13 characters instead of 14, the “a” being used twice in each word. How it could be used is still a mystery however.
I’m glad you’re looking at this cipher, and it seems you’re interested enough to have come up with your own transcription. How does your transcription compare to mine? Do I have any mistakes I need to look at?