So I went back and looked at all three letters. In the Chron letter, as we saw, Zodiac stated the other two blocks were going to the VTH and Examiner, in that order. In the VTH letter, he states Examiner then Chron. In the Examiner letter, he states VTH then Chron. When you put all of these together, I think you can take a good guess at the correct order. VTH appears in the first slot twice and the Chron appears in the last slot twice. The examiner appears below VTH in one and above Chron in the other.

Therefore, if you looked at this info at the time your guess as to the order based on the way the newspapers were arranged in the letters would have been correct.

Mike

I find it interesting that the Zodiac didn’t specifically stated "this is the order of the cipher" but instead left us with another way/clue to determine the order by carefully analyzing the included messages. I’m also wondering if somewhere in the process he intended all 3 parts to look statistically different, to perhaps create the illusion of 3 different encodings. Knowing that he kinda abandoned cyclic encoding w/o any other obvious reason somewhere at the end of the 2nd part.

I was thinking about how did Hardens figure out the correct order of the code blocks too. Considering, that what they claimed helped them crack it, was the assumption (that turned out to be correct) that the message will start with the letter "I" (and the correct crib "kill" of course). But how did they know which of the 3 blocks was the start of the whole message? Did they try all 3 at random to see which one worked?

It also puzzled me for a while, why did Z even bother to add random filler at the end, to make it exactly 408 characters long. Considering that he used homophonic substitution and there was no need to conceal the length of the message for that type of cipher, as unlike transpositions, for example, it makes absolutely no difference for the decoding process. Until I realized that when Z sent 3 parts of Z408 to newspapers, he did not explicitly specify the order in which they should be read, to make the whole thing harder to crack, no doubt. From that viewpoint, it makes absolutely perfect sense to use random filler at the end. And I think the "clue" in the accompanying notes that pointed to the correct order was just a slip of the tongue of sorts on his part, and not an intentional hint. If you know the correct order of the 3 parts it’s natural to talk about them in the right order, without realizing it.

However, switching to Z340, why did Z make it fit 17×20 matrix exactly again? Did he mean to split it into 2 parts each 10 lines long, or even into 4 parts with 5 lines per each, to make it even harder to decipher? I kind of doubt, because why didn’t he then do it? Why go through the trouble of making up a message that can be evenly split into 4 parts, adding a random filler at the end, and then abandon the whole idea? Which makes me think it was *not* intended to be split at all. So why the filler at the end then?

Well, another possibility is that Z340 was actually transposed, i.e. columns were swapped around in a predetermined order. For example, something as simple as "swap every 2nd and 3rd columns". So every 2nd and 3rd letter in each row need to change places. For example a string of "0123456789" will become "0213546879". Or it could be as complicated as using a key: http://practicalcryptography.com/cipher … on-cipher/
In that case you absolutely need filler at the end, otherwise you’ll likely not only give away the fact that transposition was used, but also reveal somewhat how the plaintext was transposed. Another possible hint that transposition was used is the "zodiac" signature at the end appearing as []. Perhaps the filled in triangle symbol should be swapped with the actual "D" from the beginning of that row? And A and I columns swapped?

Another indirect evidence that might point towards the transposition possibility is this. Every time someone suggests a new scheme that was used in encoding Z340, I always think if it can be used for the later ciphers Z sent, the "my name is" Z13 and "map code" Z32. You see, I think it went something like that. Z408 was meant as a test. Zodiac was cautious, so he sent a cipher with absolutely meaningless random ramblings just to see if it will be cracked and how fast. Or perhaps he wanted to engage the public with something relatively simple, and then up the ante with more complicated ciphers later. He wanted to play a game. And his cautiousness paid off – Z408 was too simple and it was cracked very fast. So he decides to increase the difficulty with his next cipher, but he way miscalculated with Z340 and made it too complicated. So he starts to give hints. He wants to keep playing the game. He starts sending more ciphers that would help with deciphering Z340. Which makes me think both Z13 and Z32 were encrypted the exact same way as Z340. Or perhaps it is not a game for Zodiac, but Z340 was "proof of concept" for "crack-proof" enciphering technique that Z came up with. I.e. he gave up playing the game, but he was so proud that he outsmarted FBI/police with his clever encryption method and he couldn’t resist but to taunt them with his new Z13 and Z32. Either way, if he is continuing the game with the public by giving hints, or if he is simply taunting FBI/police, Z13 and Z32 must be using the same encryption scheme as Z340. Perhaps not the exact same key (Z doesn’t want to make it too easy), but definitely the same method. In that light we can easily disregard some of the possible ways that Z340 could have been manipulated, considering that Z13 is just a single line, and Z32 is two incomplete lines. For example, reversing works for all 3 ciphers, but using complicated "routes", such as spirals, or reading them diagonally, doesn’t as there are no diagonals in Z13. Same for any schemes involving 4 quadrants, as you can’t realistically construct 4 quadrants with only 13 symbols. But transpositions still work! You can swap every 2nd and 3rd letter in a 13-symbol message as effectively as in a 340-symbol message, and it will make it harder to crack in both cases.

So I guess the point I’m trying to make is that we should always consider Z13 and Z32 when thinking up a new encryption method that Z might have used in Z340 as he’s likely used the same method in all 3 ciphers. And that transpositions do work for all 3 ciphers.

Too bad using both transpositions and homophonic substitutions makes it almost impossible to crack a 340-symbol cipher. If only Z sent longer cipher. Or more of them. Here’s an idea. Do we know for a fact that Zodiac did *not* send any more ciphers? For example, directly to police? Is it possible to confirm it with FBI/police somehow? I can see them not willing to share the text of the ciphers he might’ve sent them, but considering how much time has passed, maybe they’ll be willing to at least tell us if there are or there are not any other Z ciphers? Do we have any contacts at SFPD/VPD that can do that?

Knowing that he kinda abandoned cyclic encoding w/o any other obvious reason somewhere at the end of the 2nd part.

Jarlve, remember when you made ciphered messages for me with almost perfect cycles but then I found other false cycles to support my Wildcard Hypothesis? I have been thinking for the last couple of days about what you just said today.

If you make a message with cycles, they will overlap each other. The overlapping will create false cycles, which will disappear more and more the farther you get into the message. Cycles that maintain throughout are probably man made, and cycles that fizzle out after two or three repetitions and halfway through the message are probably false.

So, my question is, did Zodiac realize about the overlapping and abandon the cycling at the end of the message to camouflage the real cycles among the false cycles (there are only a few that maintain throughout in the 340)? Did Zodiac abandon the cycling near the end for some other reason? Laziness? To be funny? Maybe Zodiac at some level had some thought in his head about the overlapping and false cycles…

Sorry that was a bit off topic. I’ll post these thoughts in the CIPHER STRUCTURE thread as well.

Another possible reason that cycles are broken in the 3rd part is that he got tired after doing the first 2 parts and took a break before doing the 3rd part. And when he got back, possibly the next day, he simply lost track of where he was in each cycle for different letters. So he thought, screw it, and started doing substitutions randomly. Taking a break between 2nd and 3rd part also explains the apparently missing word exactly on the boundary between 2nd and 3rd parts: "and all the I have killed". I read a theory someplace, that make perfect sense, that the missing word was likely "people", and because the previous word happened to be "the", and only 1 letter that spilled over to the 3rd part was "e", when he got back and tried to find where to continue encrypting, he saw "e" on the new page, thought it was the last letter in "people" (except in reality it was "the") and continued encrypting from the next word, without realizing that he missed the entire word "people".

Kind of goes to show that he was somewhat impatient and had trouble concentrating over not very long periods of time. He also clearly didn’t check that his cipher decodes correctly, or he didn’t care enough to redo the cipher without errors. Makes me wonder if invented such a harebrained scheme for Z340 that it can’t actually be deciphered even if you have the correct key due to a fundamental flaw in the encryption method?

I was thinking about how did Hardens figure out the correct order of the code blocks too. Considering, that what they claimed helped them crack it, was the assumption (that turned out to be correct) that the message will start with the letter "I" (and the correct crib "kill" of course). But how did they know which of the 3 blocks was the start of the whole message? Did they try all 3 at random to see which one worked?

It’s a bit strange yes, but the Hardens were also somewhat prolific, resourceful. I think they found out about "LL" and then came up with the idea that the author probably started the message with "I" and saw "ILL" appearing when matching this idea to one of the parts and went with that. I like the Bettye Harden persona.

It also puzzled me for a while, why did Z even bother to add random filler at the end, to make it exactly 408 characters long. Considering that he used homophonic substitution and there was no need to conceal the length of the message for that type of cipher, as unlike transpositions, for example, it makes absolutely no difference for the decoding process. Until I realized that when Z sent 3 parts of Z408 to newspapers, he did not explicitly specify the order in which they should be read, to make the whole thing harder to crack, no doubt. From that viewpoint, it makes absolutely perfect sense to use random filler at the end. And I think the "clue" in the accompanying notes that pointed to the correct order was just a slip of the tongue of sorts on his part, and not an intentional hint. If you know the correct order of the 3 parts it’s natural to talk about them in the right order, without realizing it.

I’m personally not 100% confident that it’s random. But I agree with your assessment. Though I strongly believe that the order of the cipher was a clue to be found. And also, that for some reason he didn’t want to discriminate between the newspapers.

However, switching to Z340, why did Z make it fit 17×20 matrix exactly again? Did he mean to split it into 2 parts each 10 lines long, or even into 4 parts with 5 lines per each, to make it even harder to decipher? I kind of doubt, because why didn’t he then do it? Why go through the trouble of making up a message that can be evenly split into 4 parts, adding a random filler at the end, and then abandon the whole idea? Which makes me think it was *not* intended to be split at all. So why the filler at the end then?

Good question, to me there are many indications that the Zodiac liked order. I’m not sure there is filler at the end of the 340.

Well, another possibility is that Z340 was actually transposed, i.e. columns were swapped around in a predetermined order. For example, something as simple as "swap every 2nd and 3rd columns". So every 2nd and 3rd letter in each row need to change places. For example a string of "0123456789" will become "0213546879". Or it could be as complicated as using a key: http://practicalcryptography.com/cipher … on-cipher/
In that case you absolutely need filler at the end, otherwise you’ll likely not only give away the fact that transposition was used, but also reveal somewhat how the plaintext was transposed. Another possible hint that transposition was used is the "zodiac" signature at the end appearing as []. Perhaps the filled in triangle symbol should be swapped with the actual "D" from the beginning of that row? And A and I columns swapped?

It’s a scheme for which I already have done some work, nothing nearly conclusive though. I will probably take a more ordered look at it somewhere in the future, it’s on my todo list.

Another indirect evidence that might point towards the transposition possibility is this. Every time someone suggests a new scheme that was used in encoding Z340, I always think if it can be used for the later ciphers Z sent, the "my name is" Z13 and "map code" Z32. You see, I think it went something like that. Z408 was meant as a test. Zodiac was cautious, so he sent a cipher with absolutely meaningless random ramblings just to see if it will be cracked and how fast. Or perhaps he wanted to engage the public with something relatively simple, and then up the ante with more complicated ciphers later. He wanted to play a game. And his cautiousness paid off – Z408 was too simple and it was cracked very fast. So he decides to increase the difficulty with his next cipher, but he way miscalculated with Z340 and made it too complicated. So he starts to give hints. He wants to keep playing the game. He starts sending more ciphers that would help with deciphering Z340. Which makes me think both Z13 and Z32 were encrypted the exact same way as Z340. Or perhaps it is not a game for Zodiac, but Z340 was "proof of concept" for "crack-proof" enciphering technique that Z came up with. I.e. he gave up playing the game, but he was so proud that he outsmarted FBI/police with his clever encryption method and he couldn’t resist but to taunt them with his new Z13 and Z32. Either way, if he is continuing the game with the public by giving hints, or if he is simply taunting FBI/police, Z13 and Z32 must be using the same encryption scheme as Z340. Perhaps not the exact same key (Z doesn’t want to make it too easy), but definitely the same method. In that light we can easily disregard some of the possible ways that Z340 could have been manipulated, considering that Z13 is just a single line, and Z32 is two incomplete lines. For example, reversing works for all 3 ciphers, but using complicated "routes", such as spirals, or reading them diagonally, doesn’t as there are no diagonals in Z13. Same for any schemes involving 4 quadrants, as you can’t realistically construct 4 quadrants with only 13 symbols. But transpositions still work! You can swap every 2nd and 3rd letter in a 13-symbol message as effectively as in a 340-symbol message, and it will make it harder to crack in both cases.

If I’m not mistaken only one Zodiac "puzzle" has ever been cracked, the 408. So it’s appearant that he liked to make very hard puzzles. Swapping symbols is also something which I have taken somewhat of a look at but needs to be redone in a more ordered way, also on my todo list. I think you may be on to something in saying that the encryption scheme for the smaller ciphers may have been the same as with the 340, an interesting idea.