5/6/2023 0 Comments 340 cipherGiven that the instance count curve for the English alphabet is often described as “ETAOINSHRDLU…”, this tiered arrangement makes sense (as I recall, various researchers have tried to use the homophone allocation to infer which popular cryptography manual the Zodiac Killer specifically relied upon, but I don’t remember if there was a definitive answer to that question). To construct Z408, the Zodiac Killer used 7 shapes for, and 1 shape each for the rest (probably): this yields a grand total of 54-ish cipher shapes to encipher 26 plaintext letters. It’s all to do with doubled shapes, and the story starts with the Z408 ciphertext… Z408’s doubled letters Yet there’s another feature of the Z340 cipher which struck me a while back but which I haven’t got round to blogging about until now. Even so, we would still need to eke out some additional assistance (or meta-assistance) from the texts to make progress, because the odds are so heavily stacked against us. □Īnyway, given that the message contains 20 lines of 17 symbols (20 x 17 = 340) and we can see similar artefacts in rows 1-3 and 11-13, then it seems likely to me that there was some kind of major coding break after row #10.Ĭonsequently, I’ve long wondered whether the two halves of Z340 (let’s call them ‘Z170-A’ and ‘Z170-B’) used a different set of cipher-symbol-to-plaintext-letter assignments to each other: in which case, the sensible way to make progress would be to try to solve each half separately. “CUT HERE”).įinally, I’d add that Z340’s final (20th) line looks very much as if it contains a mangled ZODIAK signature, which – if correct – would probably make sense as 50% crypto padding, and 50% flipping the bird at the FBI. I’d also add that row #10 starts and ends with ‘-‘, which looks somewhat artificial – though it could just be random, it may also have some kind of meta-significance for the interpretation of the overall cryptogram (e.g. These suggest that something odd might be going on though inside the cipher: in this respect, the Z340 cipher resembles the Voynich Manuscript’s frustrating ‘Voynichese’, which looks straightforward on the surface but which turns out to have many behavioural features which are not seen in other known ciphers. * Because of the vertical symmetry of the statistical observations, the message may have been written, then split into two equal size parts and placed top over bottom. This appears to be intentional and indicates that lines 1-3 and 11-13 contain valid ciphertext whereas lines 4-6 and 14-16 may be fake. * Lines 1-3 and 11-13 contain a distinct higher level of randomness than lines 4-6 and 14-16. This indicates that the cipher is written horizontally and rules out any transposition patterns that are not strictly horizontal. * Statistical tests indicate a higher level of randomness by row, than by column. For example, the FBI’s Dan Olson pointed out a few years ago that: It has long been pointed out that the Z340 cipher sports a number of idiosyncratic features that are not present in the earlier Z408 cipher. But is that the whole story? Personally, I’m not so sure… Unusual Aspects of the Z340 The Z340 certainly resembles Z408, insofar as the cipher shapes employed in both were very similar, and that certainly lends support to the widely-held presumption that Z340 uses the same kind of ‘pure’ homophonic cipher system. The 408-symbol-long Zodiac Killer cipher (‘Z408’) was cracked by Donald and Bettye Harden in 1969 while the next 340-symbol-long Zodiac Killer cipher (‘Z340’) arrived not long after: ever since then, there has been a widespread presumption among researchers that the later cipher would just be a more complicated version of the earlier cipher (e.g.
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