recently added more old issues of the S.F. Examiner newspaper to its archives. I found this old article about Z340. I’ve never seen it before!

Someone on Quora asked, “How do people know that the Zodiac Killer’s cyphers aren’t just gibberish that have no real meaning?” I responded with the following article which I also posted on Quora:

There are four total ciphers: Z408, Z340, Z13 and Z32. Of the four, only Z408 has been solved. Z13 and Z32 are too short, so verifying solutions would rely on extraordinary evidence such as discovering the keys from Zodiac himself, or by finally catching and questioning him if he’s still alive.

As for Z340, there are a few bits of evidence that could be put in the “it’s gibberish” column:

  1. A non-gibberish cipher would probably have been solved by now.
  2. Zodiac liked to mess with people (especially to make law enforcement look bad), so making gibberish ciphers is right up his alley.

But there’s really no good test to conclude once and for all that the ciphers are gibberish, apart from an admission from Zodiac himself. You could easily create a gibberish plaintext yourself and make a cipher from it, and it could be the next famous unsolved cipher.

On the other hand, there have been some interesting papers on the topic of the Beale ciphers that present some evidence that they are hoaxed:

  2. Cryptanalysis of Beale Cipher Number Two

But apparently they are not enough of a “smoking gun” to fully convince everyone of the hoax hypothesis for the Beale ciphers.

It is possible that there is some characteristic of Z340 that could be discovered, and would only be present if the message was gibberish. I’m really curious to know if such characteristics could be discovered from homemade gibberish ciphers made to resemble Z340.

Nevertheless, there are still many things that can be put in the “it’s not gibberish” columns:

  1. Z340 uses an encoding scheme that hasn’t been fully tested yet. Maybe he used a traditional type of pen and paper cipher that hasn’t yet been exhaustively explored. For example, there are so many ways to rearrange the plaintext before assigning symbols. Or maybe he invented his own scheme that no one has guessed yet. When Z408 was cracked, the papers talked about how the solvers took advantage of patterns found in the cipher text. Zodiac could have focused on somehow removing those patterns from Z340. Or maybe he found some obscure idea in a book or one of those pulp fiction detective stories from back in those days (they were popular and often included ciphers)
  2. Zodiac was sloppy in making Z408 (details here), and thus may have made too many mistakes in Z340, which makes it more difficult (or impossible) to solve. (I suppose this could have effectively turned it into gibberish)
  3. There are clues in Z340 that have significance to cryptanalysts. Many of them are detailed here: Encyclopedia of observations For example, would a gibberish cipher really have the periodic ngram bias described there?
  4. On the 6th row the cipher text, he crossed out some symbol and wrote a backwards K above it:

    If the message is gibberish, why did he bother to correct the mistake? Was it just to give the false appearance of a real message? Or was he truly concerned about the integrity of the cipher text?

So, I think gibberish is a real possibility, but I still believe there might be a real message in there, especially since we still haven’t exhausted all the codebreaking possibilities.

On the other hand, if another 50 years goes by without a solution… 🙂

(Note: here’s a similar article I wrote a long time ago about this same topic: Cipher Legitimacy)

Reelz is airing a new episode of Real Story of…, a docu-series that “unpicks fact from fiction with interviews from the real people behind these extraordinary events”.

I was interviewed briefly about the Zodiac’s ciphers. Let’s see if they included the footage. 🙂

The episode airs tomorrow, February 6th 2018, at 9PM ET/PT on the Reelz network.

UPDATE: Here’s a video promo:

Catch me and fellow Code Team member Ryan Garlick on the “Behind True Crime” podcast, where we chat about the Zodiac case and the ciphers:

The finale of “The Hunt for the Zodiac Killer” features code team member Craig Bauer’s solution to Z340 which made quite a splash in Zodiac and crypto communities.

Much has been written about it on other sites already so I’ll direct you to them:

Yesterday, Craig released a PowerPoint presentation with more details about his solution:

Click here to download (PowerPoint format)
Click here to download (PDF format)

Or, view the slides directly below:

Craig’s conclusion about his solution:

I believe the solution presented here is fundamentally correct. By this, I mean that in correcting errors made by Zodiac, I may have ended up with a couple of incorrect words, but I don’t believe I am off by more than that.

So, what do you think? Is Craig on the right track?

In my forum posts and presentations I’ve often needed a way to mark up Zodiac’s ciphers to communicate ideas about them. Forum member Largo created an excellent Zodiac ciphers font which made it possible for me to make a web-based tool to marking up and highlighting the ciphers.

It is called Cipher Explorer and you can use it at this link:

Here are some examples of how you can mark up the ciphers:

Here is a quick tutorial video showing how to use the tool:

I hope you find the tool useful! Feel free to pass along any suggestions or problem reports. I hope to eventually integrate this tool with the nicer features from the Webtoy and CryptoScope.

The first episode of “The Hunt for The Zodiac Killer” made a big splash and scored almost 1.4 million viewers when it aired this past Tuesday:

Check out some of the reactions from Michael Butterfield, Tom Voigt, and Nick Pelling. Join the conversations surrounding the show at Mike Morford’s forum and Tom Voigt’s forum.

Here’s the teaser for the next episode:

And Kevin Knight gives us an overview of codebreaking and CARMEL:

Stream full episodes on (if you authenticate via your cable provider). Or pick up the episodes a la carte on Youtube:

I’m exciting to see what these code nerds turn up next. 🙂

Code team member Craig Bauer talks about his experiences during “The Hunt for the Zodiac Killer”:

Attacking the Zodiac Killer

My lips are sealed as to what happened (why ruin the suspense?), but the show premieres Tuesday November 14, 2017 at 10pm EST. It’s titled “The Hunt for the Zodiac Killer.” All I’ll say for now is that it was a rollercoaster ride. For those of you who would like to see how the story began for me, Princeton University Press is making the chapter of my book on the Zodiac killer freely available for the duration of the mini-series. It provides an excellent background for those who wish to follow the TV team’s progress.


Largo on morf’s Zodiac forum shared with us his very nice Z340 and Z408 fonts that had been bundled with his “Peek-a-boo” tool for visualizing transpositions. I combined the fonts into a single font file and adapted them for use on the web.

See if the fonts will render properly in your browser:
Click here

Download the font file (in TrueType format):
Click here

Many thanks to Largo for his great work on the font!