This new Zodiac-related iPhone app was released recently by Rene Lowack:

Reveal the mysterious secret of the still unsolved encrypted Zodiac letter.

Zodiac was a serial killer active in California during the late 1960s and early 1970s. After killing, he wrote letters to local newspapers and demanded to publish them.
Some of them contained also encrypted messages. Only one of these cryptograms has been solved. The killer’s true identity is still unknown.

It’s time to reveal his secret now.

– Encrypted message 408 part 1 including solution
– Encrypted message 340 (still unsolved)
– Statistic view
– Current plaintext and substitutions
– Manual substitutions
– Randomized substitutions
– Background information

For fun and addictive games you can play on your smartphone, check out slot online indonesia.

Screenshots: (more…)

In Part 1, we looked out how to use Project Gutenberg‘s large collection of about 39,000 digitized books to apply cribs to cipher texts to try to tease out solutions. Another way we can use the collection of books is to see if any of the unique words and phrases used by the killer in his many correspondences can be found among the books. Did the killer use a unique writing style that was similar to the style of another author? Did he use relatively rare words that can only be found in a few sources? Can any of his many misspelled words be found in common usage by other authors, suggesting a connection? (more…)

One way to attack a substitution cipher is to guess what part of the plain text solution might be, “plugging” it into where you think it might fit in the cipher text, and then seeing if you can get more of the solution to appear in the rest of the cipher text. Known as a “crib“, this type of attack can be useful if you get lucky and pick the right text.

Donald Harden
Donald Harden, along with his wife, solved the 408-character cipher within a week after seeing it. (Image courtesy of
With skill and determination, Donald Harden and his wife got lucky. Their intuition that the killer used the words “I” and “killing” in the plaintext solution, combined with the fact that “L” is the most commonly doubled letter in English, led to their success in solving the first cryptogram sent by the Zodiac killer.

partially solved 408 cipher
Even with only the small phrase “I LIKE KILLING” used as a crib, other easily solved pieces pop out of the puzzle.
Hardens crack the Zodiac code
Fast forward over forty years. Luck continues to elude codebreakers who are still trying to unlock the remaining mysteries. Our tools have gotten faster and more sophisticated. There are still no definitive solutions to the remaining cryptograms, but we can use new tools to try out new ideas. (more…)

Retired Vallejo officer Lyndon Lafferty has been getting a lot of attention for his book in which he claims to know who the Zodiac killer was. The numerous criticisms of his claims aren’t mentioned by the various news stories, but you can find them here, here, here, here, here, and here.

Lafferty claims to have solved the unsolved Zodiac ciphers, but fails to provide details on his solutions. Like many of his other claims, he expects you to take his word for it. To make matters worse, instead of sharing the solutions outright, he says he intends to profit from them:

The detailed explanation and analysis, including the unbelieveable and undeniable pattern, will be offered for sale at the first opportunity.

Would you pay him?

Over forty years of frustration have passed since the Zodiac killer first sent his mysterious 340-character cipher to the San Francisco Chronicle. It only took a week for two teachers to solve his previous cipher. But many thousands of people, over four decades, have tried to crack the mystery of the 340-character cipher, to no avail. You may have seen many would-be solutions in news stories and on the internet. The 408-character cipher was solved with a definitiveness that defies any possible doubt, because it is impossible for the Harden’s key (Part 1, Part 2, Part 3) to produce such an easily understood plain text message purely by chance. No such solution yet exists for the 340, despite numerous claims to the contrary.

So, with so much failure and defeat confronting us, should we just accept the possibility that the killer, frustrated by the swift unlocking of his previous secret message, simply created a fake cipher to keep us all busy all these years?

Mike Cole of has released a tool that lets you create your own Zodiac-like cipher texts using homophonic substitution:

Cipher Generator.


I think this tool is very useful for creating test ciphers that can be fed into cipher solving tools such as zkdecrypto, Zodiac Decoder, and CryptoCrack. Give it a whirl!

The killer’s first cipher was solved rather quickly by amateur codebreakers because they guessed that the killer would use words such as “I” and “kill”. Can similar guesswork help us solve the unsolved 340-character cipher? This is something people have been trying for years. But nobody has yet unlocked the mystery.

Zodiac sent many letters over the years, taunting the public about his crimes. From this collection of plain text, we can see what words he really likes to use in his writings.

Here are the results of an experiment that uses an algorithm to detect phrases and words that repeat in his writings. Perhaps somewhere among the results is something that might appear in the real solution of the 340-character cipher, if it indeed contains one.

Welcome to the Zodiac Ciphers blog.  Here I will try to post all the latest news on efforts to solve the mysterious Zodiac ciphers, which, with only one exception, have remained unsolved for over 40 years.

The Zodiac Killer was a serial killer who claimed several victims in Northern California in the 1960s and 1970s.  He terrorized the area with his crimes, letters, and taunts, and has never been caught.  Some of his letters included mysterious cryptograms.  Only one has been solved definitively.  Do the rest of them contain any real messages?  If so, would they shed any light at all on the identity of the mysterious killer?

Read more about the Zodiac Killer here.

The old Zodiac Ciphers wiki, which was previous found at, was being overrun by loathsome spammers, so I had to take the site down and convert it over to the new location, where I have been able to lock it down:

Let me know if anything appears to be missing!

Also, contact me if you are interested in contributing content to the Wiki, a place to collect fact-based observations, experiments, and analysis of the Zodiac ciphers.