"My Name Is" Cipher Motivation

If you have anything beyond a cursory interest in the Zodiac Killer, you probably know that he created a cryptogram in which he purported to encipher his name. This cipher is often referred as the My Name Is cipher because that's the phrase the killer used to introduce it. Alternatively, people sometimes refer to it as the 13 cipher, a reference to the number of symbol instances.

My Name Is Cipher

A little-known and infrequently-discussed part of this cipher is the probable motivation that the killer had for creating it, namely a particular newspaper article in the Examiner. There is a passing, indirect reference to the story in Robert Graysmith's Zodiac [1], but one that neither develops the proper association with the cipher nor explores all aspects of its relevance.

The pinnacle of the Zodiac's impact on the San Francisco Bay Area occurred in the aftermath of taxicab driver Paul Stine's murder. A near panic resulted from the combination of the killer: (a) striking in the city itself (as opposed to the North Bay), (b) becoming more unpredictable as evidenced by his willingness to break previously established behavioral patterns such as targeting only couples, and (c) threatening to kill school children.

Predictably, the massive level of concern over the elusive serial killer resulted in deluge of media attention. For approximately a week just after the middle of October in 1969, both the Chronicle and the Examiner published a constant stream of stories about the Zodiac, sometimes multiple stories per day.

It is within this time frame that we find the nearly certain source of motivation for the My Name Is cipher. On October 22, 1969, the Examiner published three separate stories about the Zodiac. Being the day after the infamous Jim Dunbar Show incident, there was an obligatory story covering that fiasco [2]. Another, rather well-known story [3] documented Joe Stine's (Paul's brother) message to the Zodiac. Interestingly, the sibling published his daily work routine and challenged the killer to come find him.

The article of interest, however, wasn't one of these front page stories; rather, it was an article relegated to page nine [4]. Entitled Cipher Expert Dares Zodiac To 'Tell' Name, the story described "a challenge perhaps unique in the annals of American crime...." Specifically, the president of the American Cryptogram Association (ACA), Professor D.C.B. Marsh — who had previously validated the Harden's solution to the 408 cipher — dared the Zodiac to construct a cipher that legitimately enciphered his name. The article included the following quotes from Dr. Marsh:

The killer wouldn't dare ... as he has claimed in letters to the newspapers ... to reveal his name in a cipher to established cryptogram experts.

I invite 'Zodiac' to send to The American Cryptogram Association, care of Dr. D.C.B. Marsh. president. ... a cipher code — however complicated which will truly and honestly include his name — for study by myself and my colleagues in the association.

The relevance of this dare is patently obvious. Marsh publicly challenges the Zodiac to create a cryptogram in which he honestly enciphers his name, and the killer constructs a cipher that he introduces via the phrase "My name is."

Clearly, the Zodiac did not send the cryptogram to Marsh, as had been requested (this non-public way of satisfying the challenge was apparently unacceptable to the attention-craving serial killer). Neither did he respond in a time frame that most would have expected. But these details matter little. In fact, the timing itself provides yet another reason to conclude that what we have here is a specific instance of cause and effect. As mentioned, this article was published in the Examiner on October 22, 1969.  Six months to the day later, April 22, 1970, the people of the San Francisco Bay Area were reading about the My Name Is cipher in the Chronicle [5].

This relationship between the Examiner article and the My Name Is cipher may well mean there is an even higher likelihood that the cryptogram does indeed encipher some form of the killer's name; the reasoning being that the Zodiac would have felt compelled to abide by the rules of the challenge in order to legitimately win the dare and thereby prove his intellectual superiority to Dr. Marsh, the ACA membership, and the rest of the cipher-solving world.

So, once again, all we need to do is solve the cipher...


[1] Robert Graysmith. Zodiac. New York: Berkley Books, 1987. 122.
[2] Hubert J. Bernhard. “TV 'Zodiac' Reneges on Surrender.” San Francisco Examiner (Oct. 22, 1969), 1.
[3] “A Challenge to the Zodiac.” San Francisco Examiner (Oct. 22, 1969), 1.
[4] Will Stevens. “Cipher Expert Dares Zodiac To ‘Tell’ Name.” San Francisco Examiner (Oct. 22, 1969), 9.
[5] Paul Avery. “Zodiac Sends New Letter–Claims Ten.” San Francisco Chronicle (Apr. 22, 1970), 1.

Full Article

Cipher Expert Dares Zodiac to 'Tell' Name

Michael Cole


  1. Richard Grinell 5 January, 2016 at 12:18 Reply

    Bearing in mind that this article ran on October 22nd 1969 and his next cipher was issued on November 8th 1969, only 17 days later, is it possible that the 340 Cipher was the reaction, but due to the failure of a satisfactory decryption of his ‘masterpiece’, the Zodiac felt compelled to issue a complimentary cipher on April 20th 1970 to push people in the right direction.
    A cipher of only 13 symbols is effectively beyond decryption, it is simply too short to be permit reasonable verification beyond a reasonable doubt and the Zodiac must have been aware of this, but as an accompaniment to the 340 Cipher, it most certainly isn’t . This may explain the quick response of 17 days to the original challenge, but as his impatience grew, his hand was forced into supplying us with an additional push in the right direction. Hence his reference to the previous cipher “This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is….”. It seems to insinuate to me the Zodiac is expressing exasperation and impatience at the failure of authorities to rise to his challenge. A form of reiteration.
    Maybe he was expanding on the curious feature on the 20th line of the 340 Cipher, where his pseudonym is vaguely presented.

    • Michael Cole
      Michael Cole 5 January, 2016 at 20:19

      …is it possible that the 340 Cipher was the reaction…

      Sure, it’s possible. But, I just don’t see it. The 340 is much more of a 408 version 2 than a response to Marsh. Just take the 408 (17 column organization and all), reduce the symbol instances, increase the symbol count, add one or more complexities that, to date, have made the thing impossible to solve, and voila: you have the 340.

      Plus, there is no indication accompanying the 340 that it has anything to do with the challenge, unlike the My Name Is cipher. It’s one thing not to the send the cipher to the ACA, but explicitly introduce it with “My name is”; it’s another not send it to the ACA and not give any kind of indication that the cipher relates to the challenge.

      I don’t assign much meaning to some version of “Zodiac” showing up in the last line of the 340. Based on the 408, we should expect part of that line to be filler. He was likely just playing around with his persona’s name in the filler.

      I also doubt he was too bothered by people not solving the 340. I suspect he did want it to be solved, eventually. But, he was probably fine with people trying to solve it and failing. I read the “By the way have you cracked the last cipher I sent you” as the typical rub-it-in-your-face type of taunting.

      That’s my take, anyway…

  2. Huru Guru 5 January, 2016 at 13:21 Reply

    “In fact, the timing itself provides yet another reason to conclude that what we have here is a specific instance of cause and effect.”

    If the Zodiac Killer were motivated to meet the challenge of Dr. Marsh (Oct. 22, 1969), isn’t it more likely that the killer would encipher his name in the 340 cipher, postmarked: Nov. 8, 1969? So far, even to cipher experts, the 340 doesn’t seem to be presenting itself as a thing of elegance.

    “The relevance of this dare is patently obvious. Marsh publicly challenges the Zodiac to create a cryptogram in which he honestly enciphers his name, and the killer constructs a cipher that he introduces via the phrase ‘My name is.’”

    The overwhelming majority of people do follow convention in calling the 13-symbol cipher/letter, the “My name is.” This unfortunate circumstance, I am convinced, continues to severely restrict the investigative community’s (at least the amateur one’s) search for clues.

    I could just as reasonably assert (making an equal number of assumptions, if not fewer) that the killer’s intent wasn’t to “introduce” the 13-Symbol cipher in the next (double-spaced) line, but rather to offer a fill-in-the-blank – say, for a very short name. 😉 In other words, like a teacher administering an objective test, the Zodiac was prompting an answer from pupils clever enough to have solved his 340 cipher masterpiece, which had been sent over five months earlier, and remained—as much as Zodiac could reliably assure himself—unsolved.

    • Zodiac316 5 January, 2016 at 13:46

      I like your last paragraph about a teacher. Zodiac was a teacher, he cracked his own code. The first clues to Zodiac’s identity were in his first 3 July 31st letters, the finished product was when Don Harden solved the 408 cipher. Don Harden’s Page 3 worksheet was meant to stand out from the other two. Harden labeled the 1st two worksheets roman numeral I & II. The 3rd page was labeled page 3 with the number. What makes this interesting is, the 1st three Zodiac letters each containing 1 part of the 408 cipher had one page that stood out from the other 2. In the first 2 letters, Zodiac said (Dear Editor, I am the killer of the 2 teenager’s last Christmass. On the 3rd letter,he wrote,(Dear Editor, this is the murderer of the 2 teenager’s last Christmass.) Also, on Zodiac’s 3rd letter which stood out from the other two, Zodiac wrote (over) at the bottom of that 3rd page,which he didn’t do with the 1st two pages. On Don Harden’s worksheets, Harden wrote the word (over) at the bottom of only his page 3 worksheet just as Zodiac with the 3rd letter. You can’t have all these things happen between Don and the Zodiac, and it just be coincidences, Don Harden was the Zodiac Killer, I guarantee you that. The most important clue that Harden was the Zodiac was when Harden underlined each separate word of (I will not give you my name) on his 3rd page worksheet. There was absolutely no reason to underline those words , other than to let them know he was the guy they were looking for.

    • Michael Cole
      Michael Cole 5 January, 2016 at 20:51

      Thanks for the reply. However, I don’t think you’re going to convince very many people that Don Harden was the Zodiac. Plus, offering “guarantees” in this case usually doesn’t work out too well. It reminds me of Gareth Penn guaranteeing that everything in Times 17 is true. Here’s a funny story about that.

    • Zodiac316 5 January, 2016 at 21:57

      People who will not even consider Harden a suspect are either foolish, or they don’t want the case solved so they can keep trying to con the public into buying their books. I know also that not everyone who writes a book on Zodiac is a con. People have said the same thing about Ted Bundy, Gary Ridgeway, and others, until it was proven that they were the right guy. Compare the spacing of letters and symbols on Harden’s worksheets to that of the 408 code sent in by Zodiac. Look at the upside down letter T with the big gap between that and the letters O & P in the video below . Not just those letters , but other samples that can be seen in the following video. https://www.youtube.com/watch?v=4erObVXM_zM

    • Michael Cole
      Michael Cole 5 January, 2016 at 20:28

      I see you and Richard have similar thoughts regarding the 340 and Marsh’s challenge. As I explained above, it doesn’t feel right to me.

      I suppose the 340 and 13 could be related in some meaningful way, but I see nothing obvious to suggest it.

  3. Huru Guru 5 January, 2016 at 13:30 Reply

    Just a note to readers & first poster, my response was typed and sent before any comments were visible (at my web browser’s end). My post above is responding directly to the new Zodiac Revisited article. [I see that Mr. Grinell and I even used the term “masterpiece” independently.]

  4. Richard Grinell 7 January, 2016 at 04:14 Reply

    “Don Harden was the Zodiac Killer, I guarantee you that.”
    The only way you can guarantee Donald Harden was the Zodiac Killer, is if you were Donald Harden. However Donald Harden is dead and you are not, so you cannot guarantee anything.
    From what I gather Donald Harden is your prime suspect, that is fine, but that is as far as anyone can go, because nobody knows for sure.

    • zodiac316 8 January, 2016 at 05:48

      Not true, the errors and other things Harden did in his worksheets alone prove he was the guy. Have a look at this video, and pause it at 5:34. See the comment section where there is only one comment that I posted which explains the problem between Harden’s number 1 worksheets, the partial one that was printed in the S.F. Chronicle, and the number 1 worksheet seen in Graysmith’s book. https://www.youtube.com/watch?v=PfanqTkdtyA

    • zodiac316 13 January, 2016 at 13:40

      Guarantee that Concerned Citizen was at least Zodiac, especially with the misspelling of signature, cryptogram’s, and the word mentioned without the second letter e? Please forgive the absence of my “signature” or name. Right there he said he was Zodiac. His signature was the crosshairs symbol that he signed on the bottom of all his letters. He could have just said,” please forgive the absence of my name.” But he made it a point to clue in on the signature crosshairs symbol not being left on the card.

  5. Steve 7 January, 2016 at 17:10 Reply

    Fascinating observation. There is simply no question that Zodiac read SF newspapers, particularly the SF Chronicle, closely and often responded to specific articles like the 10/18/69 SF Chronicle article calling him a clumsy criminal. The 13 symbol cipher certainly seems like a response to this cipher expert challenging him to provide his real identity in the next cipher. Not only is the 13 symbol cipher unsolvable but I would suggest that whatever the intended solution is/was, it almost certainly does not contain any real identifying information. The 408 cipher promised to reveal his identity and, as our cipher expert points out, failed to live up to his promise. Zodiac is a liar. Go figure… I will still insist that his game-playing with his own identity is a (perhaps the…) fundamental signature of Zodiac. Sorry, hg. 🙁

    • Michael Cole
      Michael Cole 7 January, 2016 at 23:14

      Thanks Steve. I generally agree. However, I suspect the killer may have put some version of his name into this cipher, specifically because it was a dare. Of course, it’s certainly possible he didn’t.

    • Huru Guru 15 January, 2016 at 22:53

      “Sorry, hg.”

      Sorry to **me** for what? Your tenuous convictions such as, “certainly seems,” “it almost certainly does not,” and “I will still insist”? No need to come out of retirement; save the rhetorical apologies and frownies for your suspect’s “cryptic messages and collaged postcards,” which we were assured would be forthcoming in a grand unsealing, scheduled for… 2015. 🙁

  6. Richard Grinell 12 January, 2016 at 06:06 Reply

    The Zodiac wrote in the 408 ‘I will not give you my name’, but not necessarily his identity. In the Debut of Zodiac Letter he wrote “By the way, are the police having a good time with the code? If not, tell them to cheer up; when they do crack it, they will have me.” In this instance he was telling the truth.

    • Michael Cole
      Michael Cole 12 January, 2016 at 08:51

      Yeah, I always thought it was an important distinction that in his the letter to the Chronicle (and, btw, only the Chronicle), the killer wrote “In this cipher is in my identity,” yet, in the 408 he proclaimed “I will not given you by name.” He may well still be telling the truth in that the two are not necessarily the same thing.

      Are you saying something similar regarding the “…they will have me” line?

    • zodiac316 12 January, 2016 at 19:00

      What makes the most sense with the “they will have me” is this

      ” By the way, are the police having a good time with the code? If not, tell them to cheer up; when they do crack it, they will have me.” Zodiac didn’t mean when “they the police” would crack it, he was talking about when “they the Harden’s” would come forward to crack it. They came forward, and they had him. He used a double entendre on them. That is what seems to make the only sense since he did say “they will have me” once it was cracked. There wasn’t a name in the decoded message, so what other possible way would they have him?

    • zodiac316 13 January, 2016 at 10:31

      That is fine if you feel the need to answer on behalf of everyone , but just answer these coupple of questions.

      1. Why did Zodiac never mention Harden solving his code? Don’t you think he would have loved to rub it in the face of the police that a school teacher and his wife could crack the code, but they couldn’t?

      2. For the message you just replied, what way did they have him then? Zodiac said when the code was cracked, they would have him. Which way did they have him?

      3. Did the S.F. Chronicle say in their article where the 3 part cipher was printed, that kids had been shot? If so, why did the Harden’s say they didn’t know that kids had been shot if it was written right there next to the cipher codes that they copied to their worksheets? Why was Harden then hiding from the media as was reported by someone at his school after the code was cracked?

      4. Why did Harden underline for no reason, (I will not give you my name?)

      5. Do you feel it was only just a coincidence that the Concerned Citizen 408 code key that was mailed directly to Sgt. John Lynch on Aug. 10 1969, a day after it was shown that Harden broke the code, and the same day after an Aug. 9 1969 newspaper article saying that Sgt. Lynch had talked with Harden on the phone, had is worksheets and was studying them against the Zodiac codes and letters? Harden sent in that key because he was nervous that Lynch was studying his worksheets ,he had to get the attention diverted away from himself. Harden was the Zodiac Killer, you people just don’t want to face reality.

    • Michael Cole
      Michael Cole 13 January, 2016 at 22:15


      “That is fine if you feel the need to answer on behalf of everyone , but just answer these coupple of questions.”

      I replied to you directly. I’m not sure how that translates into answering on “behalf of everyone.”

      “1. Why did Zodiac never mention Harden solving his code?

      This is like Thomas Horan saying that since the killer did not say “This is the Zodiac” at Lake Berryessa, he was not the Zodiac. Generally, I stay away from trying to read into the infinite number of things that the killer did not do.

      “2. For the message you just replied, what way did they have him then?

      They didn’t. He built up a false expectation and then shattered it when he revealed that it was a lie. So what?

      Sorry, I don’t have time to get into it your remaining points…

      I do have a question for you, though. What if you’re wrong? Back in 2007, I attended this event. I listened to the Harden’s daughter speak about her parents involvement with the case. What she described meshed perfectly well with what we know of the Hardens, which is to say it doesn’t fit with your view. If you’re wrong, your accusing somebody of being a serial murderer; somebody who did nothing more that work hard to try to help solve the case. It reminds me of the Toschi debacle in 1978 when reporters were asking Toschi if he was the Zodiac.

      Of course, by this point, I know the dynamics of this case well. You will undoubtedly not be swayed by anything I have to say and probably…

    • zodiac316 14 January, 2016 at 13:21

      I completely understand your point. I wouldn’t want to accuse anyone who I thought could possibly be innocent. Things that Leslie has said are mostly what her parents had claimed, info in the news articles. If they were involved, they wouldn’t have let her know at that time. They would have had to make it look good in front of her. I do question things she has said at the meeting. How could someone know where Leslie hid the 340 papers her mother was said to be working on, and then steal it? She said someone beat her to the house before she could get the stuff. How would someone know about the hidden papers, and how would they know which wall it was hidden in? She said it was then told to her by a reporter that her mothers work was sold online. So far, nobody has been able to verify that it was sold online. I found another interview where Leslie said something totally different than at the task meeting. At the meeting she said someone, (she would hate to think it was someone possibly in the community that beat her to it.) In the interview, she said that she went to retrieve the papers and the new owners refused to turn them over to her. Two different stories that do not add up. Also, if her mother was so scared of the Zodiac that she had to sleep in the bathtub, why would Bettye have the urge to keep writing letters to editors of newspapers about the zodiac non stop ? Maybe she knows more than she has said.

    • zodiac316 13 January, 2016 at 16:37

      Michael, you wrote “Yeah, I always thought it was an important distinction that in his the letter to the Chronicle (and, btw, only the Chronicle), the killer wrote “In this cipher is in my identity,”

      You are correct with it being important, and it goes along with what I said earlier about the first two July 31st letters being different from the Chronicle letter with using the word killer in the first two, and murderer on the Chronicle letter. The writing on the Chronicle letter was written with a thicker marking pen than the other two. The Chronicle letter envelope also had Roosevelt stamps with his face facing down on the envelope, where as the first two letter envelopes had Roosevelt’s face facing up. Do you think all these things I just mentioned about the Chronicle letter being different from the first two letters could be just a coincidence?

    • John 27 January, 2016 at 20:43

      Michael, zodiac316 is one of those people who is right even when everybody else knows he’s wrong. I am sure I’ve come across this guy before on the internet and have found it impossible to have a reasonable and constructive discussion with him without him getting angry and calling me a fool. I guess to him the evidence seems strong and undeniable. That is why he often calls it “proof”. To me the whole Don Harden theory looks forced and certain facts appear to have been distorted or misinterpreted. There is some circumstantial evidence, but it is highly selective and subjective in nature.

      As for the above pictured cipher I have always wondered if the PARADICE was relating to the town of Paradise in California. Perhaps that is where Zodiac was intending to die to fulfil his bizarre fantasy of keeping the people he had killed as slaves in the afterlife. Anyway, this was just a thought I once had, and probably a dumb one at that. 🙂

    • Michael Cole
      Michael Cole 27 January, 2016 at 21:14

      Yeah, it’s part of the problem with this case. People invest years into opinions which can be neither proven nor disproven and then they are very stubborn about reconsidering them (and yes, others who don’t share my opinions about the case will say the same about me, I know…). As long as the dialogue doesn’t get too insulting, I try to have a live-and-let-live attitude about it all nowadays.

      I’ve also wondered if it was possible he (the Zodiac) could have been referring to Paradise, California. There used to be this local burger place that we would go to occasionally. Part of its decor included an historical newspaper article that talked about Paradise, California. Of course, it made me think about the Zodiac every time I saw it. Ultimately, I suspect it’s unrelated. But, you never know…

  7. Richard Grinell 15 January, 2016 at 06:25 Reply

    Here is my masterpiece Michael. Just a bit of fun, but since we were talking about the 340 and ‘My Name is Cipher,’, I devised a little way to interconnect them, In other words the Zodiac derived the 13 Symbol Cipher from the last line of the 340 Cipher using his name. We were talking about the symbols that may look like Zodiac on the last line of the 340 Cipher. Well here’s a little trick.
    If you place the correct spelling of Zodiac under the 340 one, like so in the attached diagram and simply count the alphabetical difference between the columns numerically, the first three generate three 0’s, the second three generate three 8’s, the source of the three circled 8’s in the 13 Symbol Cipher, voila ! Then notice the Zodiac symbol to the left of the three 8’s in the 13 Symbol Cipher and the upside down Taurus symbol to the right of the three 8’s in the 13 Symbol Cipher. These are both present either side of Zodiac in the 340.

    And for my next trick I shall disappear…..poof.

    • John 2 February, 2016 at 04:01

      Emma, in light of your comment about fanatics with nutty theories, you are going to love this.

      I was recently PM’d by someone on one of the forums. He evidently wanted to tell me “the real truth” about the Zodiac killer. He told me he worked as a professional analyst and had come to the conclusion that Donald Harden, Allen Leigh, Richard Gaikowski were all examples of Government operatives.

      After walking to the bathroom to splash some cold water on my face I decided to go back and ask the person what proof he had and why he was contacting me. Apparently he thought my ideas were similar to his, although I am still not sure how he ever arrived at that conclusion!

      As he explained it, his theory goes like this: All of these people were operatives in a covert Government conspiracy, but they had no idea they were operatives because they were under the influence of mind control at the time. They had been brainwashed somehow into committing the crimes and/or unwittingly helping with the cover-ups.

      He claimed that many other crimes that are still unsolved or mysterious were also examples of covert operatives: the Manson family for instance. He also believed that the guy with the crazy Harden theory was a “disinformation stooge” planted on the internet by covert Government operatives.

      I asked him why would the Government be doing this to its own population? He replied that it is all to do with the Government wanting to confuse people and find excuses to take weapons off the people and they were also experimenting on mind control as a military weapon and in order to control the population etc. etc.

      Wow Mulder, time to grab those tin foil hats! 🙂

    • Michael Cole
      Michael Cole 5 May, 2016 at 05:31

      Thanks for the comment, BPM. The discussion you’re referring to is here.

      This solution is not correct, IMHO. Any solution involving anagramming is highly improbable. Also, (a) the upside-down aries symbol being a ‘T’ and (b) multiple instances of the same symbol (the encircled taurus symbol) representing different unknowns both feel unlikely to me.

      Like Harvey Hines’s solution involving the name “KANE,” this solution is partially related to a bit of gamesmanship on the part of the killer. Specifically, he’s claiming to create a cryptogram that enciphers his name, so in the ciphertext he includes the symbols: N, A, M, E. In the case of “KANE,” three of the four letters are shared with NAME and the K just happens to be another symbol that’s there. The reddit solution involves anagramming that explicitly uses the word NAME.

  8. Johannes 23 August, 2016 at 15:52 Reply

    I propose that Z13 is basically a transposition cipher. The basis for this solution is that the inverted T in position 4 right-to-left gives a strong clue to mirror the string vertically, with the inverted T becoming T, the 2 M’s becoming W’s, and another change that I will make later (*). Writing the Zodiac sign as 0, the resulting string is:

    A E N 0 8 K 8 W 8 T N A W

    The rest is a transposition, which I will describe in three steps.

    1. Mirror the string horizontally, i.e. read it from right to left.

    W A N T 8 W 8 K 8 0 N E A

    2. Shift left (substring, positions): (K8, 2), (right N, 4), (right A, 3).

    W A N T 8 K N 8 W A 8 0 E

    3. Shift right (substring, positions): (Zodiac sign, 1).

    W A N T 8 K N 8 W A 8 E 0

    As the symbol 8 is an H within an O, replace the first 2 instances by O and the last instance by H.

    W A N T O K N O W A H E 0

    (*) An inverted A is two t’s joined at the base, so replace the second A with T. (Or, if you are a purist, replace the second A with 2 T’s and move one T after WANT.)

    W A N T O K N O W T H E 0

    So this is just a tease: “My name is… Want to know the Zodiac?”

    • Michael Cole
      Michael Cole 7 September, 2016 at 16:09

      Thanks for sharing you solution. Unfortunately, I have to admit that I don’t find it convincing…

  9. Johannes 23 August, 2016 at 16:13 Reply

    The October 22, 1969 letter from Dr. D.C.B. Marsh increases the plausibility of my solution to the Z340 cipher in the Zodiac’s November 8, 1969 letter. Being challenged by people who boast of their intelligence, what can be smarter and more fun than giving them a message that, almost all in the clear, calls them IDIOTS and contains an EASY WC Piece Of SHIT?

    In addition to local transposition, I hypothesize that the Z340 cipher was composed with the following criteria:

    1. Most of it is just gibberish, with only very little meaningful text, which is in the clear with just a little local transposition.

    2. The strings of meaningful text are located right after Zodiac signs. The basis for this criterion is that all 3 strings of easily noticed meaningful text, on lines 13, 18 and 20, start right after a Zodiac sign.

    3. Vertically or horizontally mirrored characters substitute their base characters as in Z13, e.g. inverted T and mirrored D for T and D in line 5, and mirrored C for C in line 18.

    4. Some of the symbols may have undergone the same substitution as in the Z408 cipher.

    Below I list the meaningful text, if any, next to each of the 9 occurrences of the Zodiac sign.

    Line. Text to the right of the Zodiac sign
    03. HI
    05. TIDIOF = IDIOTS (ending F encoding S as in Z408)
    07. –
    08. –
    10. –
    13. EASY (initial circle with middle dot encoding E as in Z408)
    16. –
    18. WCPOSHT = WC Piece Of SHT
    20. ZODAI = ZODIAC

    Probably on purpose, the total number of meaningful characters, 24, equals the total number of + symbols.

    • Michael Cole
      Michael Cole 7 September, 2016 at 16:06

      If you’re willing to assign meaning to only 24 of the 340 symbols instances (~7%), then there are effectively an infinite number of solutions that one can propose; many of which are sure to be more compelling than yours.

      “ZO[triangle]AIK” in the ciphertext is clearly a reference to “ZODIAC,” but it’s also in the last half of the last line, which is almost certainly filler.

    • Johannes 12 September, 2016 at 20:17

      My approach is not just to assign meaning to only 24 of the 340 symbols, but to assign a straightforward, plain-sight meaning which follows a simple rule: each meaningful string starts after a Zodiac sign. There is just one solution with these features, and it has the remarkable property of perfectly fitting the Zodiac’s psychology in the context of the experts’ challenge, since the experts’ humiliation is maximized when the message that they cannot see is in plain sight according to a simple rule, calls its readers “idiots” and is an “easy piece of sht”.

      The likelihood of my solution is maximal according to psychology. Conversely, the problem of those who cannot see it is too little psychology and too much cryptography. What makes you think that the Z would play by the rules of cryptography if he didn’t play by the most basic rule of life?

      Interestingly, since my position is falsifiable but not verifiable, it makes sense to make a time constrained bet on it, i.e. to bet $1,000 that no plaintext for the whole cipher will be found within the next 10 years. (A bet of $10,000 that no plaintext will be found within the next 100 years would imply a lot of faith in the progress of medicine!)

    • Michael Cole
      Michael Cole 12 September, 2016 at 22:16

      Well, I believe that you believe in your solution. The problem is that there are many people who fall into that category. How many other people have you convinced? I’m pretty sure the answer is: not many. Sure, you can argue it’s because everybody who disagrees with your assessment is insufficiently knowledgeable about psychology. But, that doesn’t ring true to me. More likely, it’s because your solution is not convincing. Maybe you’re right and the rest of the world is wrong. But, I doubt it.

      If we accept that the killer created a cryptogram without adhering to the rules of cryptography, then the solution could be, quite literally, anything…

      Regardless, given that the cipher hasn’t been solved in the last ~50 years — especially the last 10 years during which it’s been heavily analyzed by computer algorithms — it’s probably not going to be solved in the next 10 years. That doesn’t mean there is no valid solution. And, it doesn’t mean that some imperfect solution is the right one. It’s just unsolved. Nothing more. Nothing less.

  10. David Cobb 5 January, 2018 at 16:54 Reply

    I find the use of the Taurus symbol as a delimiter fascinating. That clue in itself could be the first step in solving the cipher. The Z13 cipher like the Z32 is obviously so short that using brute force substitution provides no benefit. Unlike the Germans and Japanese in WW2, the Zodiac wanted his ciphers solved. The Zodiac was clever enough to know that substitution alone would never lead to a unique solution. You have to take the purpose of his cipher into account on the Zodiac’s shorter ciphers. Perhaps the Taurus was Zodiac’s birth sign? Perhaps there is another significance to the Taurus sign that we are overlooking. I’m convinced that the Zodiac used delimiters in the Z340 (dashes) and in the Z32 as well (geometric shapes). The Zodiac’s use of delimiters in the Z13 may be supported by his use of delimiters in his other ciphers.
    With respect to your ‘filler’ response above. I interpret the zodiac symbol as his signature on the last line and anything that follows as a post-script. This implies that it is meaningful, not just random letters to fill the last line.

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