it will be interesting if it is i was on the skytale horse for a long time. . i skytaled to death thousands of variants and ended with a fistfull of nothing.

Here is a good example with the first section.

Text;
I HOPE YOU ARE HAVING LOTS OF FA.N IN TRYING TO CATCH METHAT WASNT ME ON THE TV SHOW WHICH BRINGO. UP A POINT ABOUT ME I AM NOT AFRAID OF THE GAS CHAMBER BECAA.SE IT WILL SEND ME TO PARADCE ALL THE

Using the Key, but still scrambled, Official version:
IRONCAOOIIERGRTMLECHETTATNWNNIAABWEITEOHSRTWTWGTAISDCCLOAPAOYCAHHO.AMBNOHALPLEVFIHSEIUCPOOFAA.SALYIFNMNTTVHAUTTMSERTONA.GETTMSBPTAHBENAHUGNLIOHEHROMFEEIDDEA

Using the ‘text’ and encoding it with a random Skytail encoder (first web based one I even tried *9 turns ; https://www.dcode.fr/scytale-cipher )
IRONCAOOIIERGRTMIHETTATNWNNIAABWECOHSRTWTWGTAISEITEPAOYCAHHSAMDCCLOAEVFIHSEIUBNOHALPLYIFNMNTCPOOFAUSALONUGETVHAUTTMSERTUGNTTMSBPTAHBENA·ALIOHEHROMFEEIDD·

There will be variations in the encoding methods modern computer vs original pen and paper. But look at how close sections of the two are:

IRONCAOOIIERGRTMLECHETTATNWNNIAABWE ITEOHSR TWTWGTAISDCCLOA PAOYCAHHO.AMBNOHALPLEVFIHSEIUCPOOFAA.SALYIFNMNTTVHAUTTMSERTONA.GETTMSBPTAHBENAHUGNLIOHEHRO MFEEIDDEA
IRONCAOOIIERGRTMIHETTATNWNNI AABWE COHSRTW TWGTAISEITE PAOYCAHHS AMDCCLOAEVFIHSEIUBNOHALPLYI FNMNTCPOOFAUSALONUGETVHAUTTMSERTUGNTTMSBPTAHBENA·ALIOHEHRO MFEEIDD·

It falls apart in sections, but the first few lines match up, as does the end. Other sections as well. Can it be this close and just be a coincidence?

NOT coincidence in my mind. Great find!

That similarity really is beyond uncanny. What more do we know about this Laffin book? Was it just a publically available tome on codemaking?

Proves the solution is the real deal.

NOT coincidence in my mind. Great find!

That similarity really is beyond uncanny. What more do we know about this Laffin book? Was it just a publically available tome on codemaking?

We know it was widely available in public libraries at the time. The yellow book mentions it and points out it was aimed at teenagers or young adults.
Very basic introduction, and suggests no military training would be needed to create the 340.

Perhaps it’s worth taking a look at other cipher types in that book and trying to apply them to the two remaining ciphers.

CONFIRMED!!!

OFFICIAL CIPHER TEXT WITH THE MISTAKES, FIRST 9 LINES OF THE 340 AS IS:
IRONCAOOIIERGRTMLECHETTATNWNNIAABWEITEOHSRTWTWGTAISDCCLOAPAOYCAHHOAMBNOHALPLEVFIHSEIUCPOOFAASALYIFNMNTTVHAUTTMSERTONAGETTMSBPTAHBENAHUGNLIOHEHROMFEEIDDE

8 TURNS*** (Name Cipher Hint?) Decodes to:

IHOPEYOUREHAVINGOTSOFFANNTRYINGLCATCHMEIATWASNTOONTHETTHOWWHITMEINGOUVSHINTACHBREIAMPAPORAIBOUTMGASNOTAFRBDOFTHETWCHAMBEMECAASEILILLSENDETOPARADCEALLTHE

https://www.cryptool.org/en/cto/ciphers/scytale

There are some variations with the encoder vs Z’s pen paper, but this is close enough to determine the 340 is a SCYTALE CIPHER !!!!

This could be the most important clue to come out of all this.

If it is a skytale cipher then the odds of Zodiac using this book, or something similar have greatly increased. Consider that we’ve known about this book the whole time, and yet no one was able to apply it in solving the z340. There’s now a compelling chance that this book may have been used to construct the z13. This is the sort of breakthrough that would be required to find a valid solution to the z13, as finding a solution in a book already connected to the case would be corroborative in itself. Obviously z340 was complex enough that even knowing about this book didn’t help, but perhaps it shows that it’s easy to overlook things. How often are cases solved when investigators go back over some of the earliest pieces of evidence, could this be such an occasion?

If he was indeed upset about the first simpler code being solved quickly and set about studying a better one, be interesting to see who checked out the code book in relevant libraries at the time between.

I have no doubt that the infamous Z uses these books in his codes.
I wonder if he did not use methods present in the book to code the Z13 and Z32, since he used two different methods in the 340 and 408 ciphers it is possible that he made the other two ciphers also in different ways,

I just noticed this and I don’t think it’s just a mere coincidence:

As early as August 10th 1969, Professor D.C.B. Marsh of the American Cryptogram Association (ACA) was commenting on the Zodiac ciphers. In the San Francisco Sunday Examiner & Chronicle, he praised Donald Harden’s deciphering skills and called the code "complicated and obviously drawn by somebody who knows his business".

"Dr Marsh told the Examiner today: "The killer wouldn’t dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name -in cipher code – would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code – however complicated – which will truly and honestly include his name".

Zodiac sent the 340 cipher to the SF Chronicle just a few months later.

Have you noticed the logo of the American Cryptogram Association?

It’s a Skytale!

I don’t think it is a Skytale cipher because Skytale is 1-dimensional and the reading rule in Z340 is 2-dimensional.

It is just that it all comes down to a different order in which the period 19 lines are read in, see example: viewtopic.php?f=81&t=4632

But even between the different orders there are many repeats because the sequences of the period 19 lines themselves are undisturbed.

Not sure if people will get this.

Someone on Reddit thinks the solution appeared in a 1950 Army technical manual. I’m not expert enough to know. It might just be that they’re similar and the source could be either.

I just noticed this and I don’t think it’s just a mere coincidence:

As early as August 10th 1969, Professor D.C.B. Marsh of the American Cryptogram Association (ACA) was commenting on the Zodiac ciphers. In the San Francisco Sunday Examiner & Chronicle, he praised Donald Harden’s deciphering skills and called the code "complicated and obviously drawn by somebody who knows his business".

"Dr Marsh told the Examiner today: "The killer wouldn’t dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name -in cipher code – would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code – however complicated – which will truly and honestly include his name".

Zodiac sent the 340 cipher to the SF Chronicle just a few months later.

Have you noticed the logo of the American Cryptogram Association?

It’s a Skytale!

Great find. It’s also on the cover of the book: