It is a very nice piece of work.

He is basing this on the low amount of repeats in the left-to-right, top-to-bottom direction and some other reading rules but he did not include period 19 into his analysis. I do not see any strong points towards the 340 being a fake cipher since a thorough untested transposition of the plaintext is all what it takes to reproduce his findings in the cipher.

He does recognize this:

It is possible that z340 is a very strong Vigenère cipher with a long keyword or uses some other, not-so-standard encryption trick that cannot be detected by an ngram-based analysis. This is indeed a possibility – but one has to keep in mind that z340 was created before computers were readily accessible to the public.

I sent him an e-mail asking him to include period 19 and made him aware of this forum.

Tom told me that he is giving a talk in Ghent, Belgium next weekend: https://0x20.be/landing/newline.php

TALK 17:00 – 17:30 : THE ZODIAC KILLER’S Z340: LIKE A FAKE CIPHER

To this day, the Zodiac Killer’s second major cipher, z340, remains unsolved. In this talk, I argue that z340 is most likely a fake cipher. This hypothesis has been put forward before, but without hard evidence. I provide such evidence, which is mainly based on the analysis of mean squared distances for ngrams. This analysis is applied across various ciphers: z340, z408, which is the other major cipher by the Zodiac Killer, twenty generated ciphers based on real texts, and twenty fake ciphers based on random letter sequences. The results show that z340 behaves unlike other true ciphers. Instead, it associates with the fake ciphers.

Wow, this is quite an interesting event overall. Many of the topics are exactly my cup of tea. Will you be there, Jarlve?

Wow, this is quite an interesting event overall. Many of the topics are exactly my cup of tea. Will you be there, Jarlve?

Hey Largo. I will not be there. How are you doing?

Wow, this is quite an interesting event overall. Many of the topics are exactly my cup of tea. Will you be there, Jarlve?

Hey Largo. I will not be there. How are you doing?

Yes, Largo, I have been thinking about you. How are you doing?

Hi,

I’m doing well, thanks. How about you?
It’s nice to see with how much enthusiasm and eagerness both of you are working on the null/skip thing. Especially the cooperation via GoogleDocs is great. Also the new version of AZDecrypt is impressive. It’s really itching to chime in, but for now I won’t do it. But it’s really great how much motivation you have right now.
I was thinking all the time whether I would use the event in Belgium for a long weekend and go there. These are really interesting topics. That’s for me to decide spontaneously.

Hi,

I’m doing well, thanks. How about you?
It’s nice to see with how much enthusiasm and eagerness both of you are working on the null/skip thing. Especially the cooperation via GoogleDocs is great. Also the new version of AZDecrypt is impressive. It’s really itching to chime in, but for now I won’t do it. But it’s really great how much motivation you have right now.
I was thinking all the time whether I would use the event in Belgium for a long weekend and go there. These are really interesting topics. That’s for me to decide spontaneously.

Thank you Largo. I am doing well. You could arrange to meet up with Tom after or before his talk.

I am doing great. The new project keeps me busy but also allows me to not worry about trying to figure out what kind of cipher he used and I can read books and work on my house.

Check out my symbol chart that shows the symbols and compares the various phenomenon, P15, P19, P29, P78, pivots, cycle patterns and regional biases. You can pick a symbol and look up what it does, if anything.

https://docs.google.com/spreadsheets/d/ … sp=sharing

I used your font, so hope you can see it. It might default to regular characters.

That’s outstanding work. He shows clearly that Z340 is either fake or at least some kind of progressive encryption or vigenere (or better).

The ciphers have always been the main factor that limit my confidence in the TK hypothesis. Either z340 is fake, or it is many levels of sophistication above z408. One would have to assume that TK wrote z408 as a counter-measures to mask his level of education. While he did that in other communications, it just isn’t very elegant as an explanation. There is a difference between using a different linguistic register in your letters than in daily life, and producing two entire mathematically incompetent ciphers.

The simpler explanation is that z408 is the product of an unsophisticated cryptographer and who was stung into producing a fake for the z340.

A more complex but not impossible scenario is that z408 was sent by a copy-cat and that z340 was Z’s response.

A more complex but not impossible scenario is that z408 was sent by a copy-cat and that z340 was Z’s response.

Copying whom? The z408 was the first Z cipher.

A more complex but not impossible scenario is that z408 was sent by a copy-cat and that z340 was Z’s response.

Copying whom? The z408 was the first Z cipher.

It’s complex and involves time travel.

I meant someone falsely taking credit.

Such a person would have to know undisclosed details of the crimes.

Yes.