Between December 1968 and October 1969 – and potentially before and after those dates, too – the San Francisco Bay Area was rocked by a series of high-profile murders. It wasn’t the method or number of the killings that set them apart, though; all things considered, they were pretty boring in their execution, and while there are claims that as many as 49 people were killed at the hand of the perpetrator, only five victims have ever actually been confirmed.
Nevertheless, these murders would become infamous, spawning books, theories, copycat killers, and even a critically acclaimed movie. Even today, popular culture is obsessed with discovering the still-unknown identity of the perpetrator.
And why? Because this killer courted publicity like no other. The Zodiac, as he dubbed himself in one of the many messages he sent to various newspapers, is as famous today for his ciphers and cryptograms as he is the murders he committed.
To this day, only two have been cracked.
Which Zodiac ciphers have been cracked?
The first message to be broken was a 408-symbol cryptogram, now known as Z408. It was sent in three parts to local outlets, and immediately set upon by both the FBI and the CIA – only to be cracked after four days by a married middle-aged couple from Salinas. It didn’t even take that much in the way of obscure or high-concept methodology to break: suspecting that the killer was after attention, Bettye Harden guessed that the message would likely start with the word “I”, and include something like “KILL” or “KILLING.” She was right, and that was enough of a wedge to force open the cipher.
The second, though – well, that took a little longer to decrypt. Half a century longer, in fact.
“On December 5, 2020, the FBI received the solution to a cipher popularly known as Z340 from a cryptologic researcher and independently verified the decryption,” confirmed an FBI statement, issued after the release to YouTube and Zodiac lore fansites of a proposed solution to a second message from the killer.
“This cipher was first submitted to the FBI Laboratory on November 13, 1969, but not successfully decrypted,” the statement continued. “Over the past 51 years CRRU [the FBI Cryptanalysis and Racketeering Records Unit] has reviewed numerous proposed solutions from the public – none of which had merit.”
That was until three hobbyist cryptographers – software developer David Oranchak, applied mathematician Sam Blake, and warehouse operator Jarl Van Eyke – finally cracked it. Well, with a tiny bit of help from the pros: “when I talked to the FBI, they only needed to make one change to the solution,” Oranchak told Zodiac lore authority Michael Butterfield back in 2020.
“We couldn’t figure out the part that says, ‘soo her,’” he explained, “[but] their cryptanalyst called me and she said she thinks it’s supposed to say, ‘sooner’ instead.”
The end result? A chilling declaration of a murderous and misspelled philosophy:
I HOPE YOU ARE HAVING LOTS OF FUN IN TRYING TO CATCH ME
THAT WASNT ME ON THE TV SHOW
WHICH BRINGS UP A POINT ABOUT ME
I AM NOT AFRAID OF THE GAS CHAMBER
BECAUSE IT WILL SEND ME TO PARADICE ALL THE SOONER
BECAUSE I NOW HAVE ENOUGH SLAVES TO WORK FOR ME
WHERE EVERYONE ELSE HAS NOTHING WHEN THEY REACH PARADICE
SO THEY ARE AFRAID OF DEATH
I AM NOT AFRAID BECAUSE I KNOW THAT MY NEW LIFE IS
LIFE WILL BE AN EASY ONE IN PARADICE DEATH
But while the trio were never shy about their breakthrough, it’s only now, four years later, that we’ve been gifted the most in-depth account of the discovery to date. In a detailed white paper, released last month, the team describe a process stretching back more than a decade – and involving quite a bit of struggle and failure along the way.
How was Z340 deciphered?
Well, it wasn’t easy. “The decryption success reported herein was preceded by the authors’ many years of failed experiments, dead-end ideas, and efforts to summarize what was known about the Zodiac case and ciphers,” the paper admits. And they weren’t the only ones: among the 61 pages are an extensive history of academic and amateur attempts to break, or even just make inroads into, Z340.
So why did this second message take so much longer to decipher? It seems that, after having his first attempt decrypted so quickly, the Zodiac killer upped his game – a lot. “It is clear that the complications introduced by Zodiac led to much delay in its solution,” the trio write. “If the cipher were simply one of the well-understood classical systems, such as homophonic substitution, transposition, or polyalphabetic substitution […] then traditional cryptanalysis and application of powerful cipher solving tools would have broken it.”
Instead, what faced hopeful criminal chasers was a slew of confounding tactics: the cipher wasn’t just set out in a rectangular grid, for example, but it also reads diagonally rather than left-to-right according to a period that changes whether it’s on the horizontal or vertical axis. The message was split into four sections of uneven lengths, and a decryption algorithm that was successful for one wouldn’t necessarily work on the next. And on top of that, as before, there were plenty of spelling mistakes to account for, further muddying the decryption process.
But despite these setbacks, the team also found themselves armed with a few tools that previous attempts to defeat Z340 lacked. Chief among them? The grand total of international accumulated knowledge on the case and cipher, courtesy of the internet.
“The online community drew a wide variety of people eager to crack the case and its ciphers, which brought many different approaches and viewpoints,” the trio wrote in their paper.
“Analysis of Z340 benefited from collecting factual information about the cipher, its context in the Zodiac case, statistical analyses of the ciphertext, and other cryptanalytic observations,” they explained. “As users on online forums discovered interesting details about the ciphers, Oranchak endeavored to preserve them [online]. This allowed other researchers to use the information as a foundational source of factual details to build upon.”
Of course, as anyone who has spent time online knows, the internet can be a mixed blessing. While on balance, the team think it was an advantage, they did note that “Z340 ’s notoriety in particular attracted the interest of people from many walks of life and with a wide range of abilities pertaining to codebreaking,” with some less experienced commentators getting “aggressively convinced their favored Zodiac suspect was the correct one and the ciphers reflected their suspect’s name or other details.”
That wasn’t the only benefit of the modern world to help with the breakthrough. Compared to 50 years ago, computer automation is both easy and ubiquitous – they’re even out there proving mathematical theorems these days. Using a collection of various decryption programs, the team were able to run through tens of thousands of potential transpositions of the cipher – a task that would be nigh-impossible to do by hand.
Who was the Zodiac killer?
As helpful as all these modern inventions were, though, sometimes the old tricks are the best – and according to Oranchak, it was the killer’s own pride that provided one major breakthrough. Back in 1969, before Z340 was written, a hoax caller rang a TV show pretending to be the Zodiac, saying that he was scared of getting sent to “the gas chamber” for his crimes – and it seems this was too much of an insult to the real deal’s ego.
“When ‘that wasn’t me on the TV show’ popped out during the solve, I jumped out of my chair and said, ‘Holy ****!’,” Oranchak told Butterfield. “That’s when I knew it was on the right track.”
“It was only a handful of words to start with. Could have very easily ignored them and moved on,” he said. “But ‘gas chamber’ really stood out.”
It may have taken half a century to solve, but we finally know what the most infamous Zodiac message was meant to say – and why. But potentially even more interesting than the content of the cipher is what it tells us about the killer himself.
Not that it reveals his identity, of course – despite all the hints he dropped, that’s never been elucidated. But after Z480 was solved so quickly, and by a couple of amateurs at that, many people thought the Zodiac, well, wasn’t that good at cryptography. The sheer complexity of Z340 seems to have put that idea to bed: “either he knew codes, or had a good intuition about how to make them,” Oranchak told Butterfield. “He definitely reacted to the Hardens[’] solution and made it much harder.”
So, now that Z340 is solved, can we finally decrypt the other two messages sent out by the killer all those years ago? According to the trio… probably not, actually. At just 13 and 32 symbols in length, the remaining messages are too short for any potential solutions to be properly verifiable – especially when, as Z340 has proven, there’s no guarantee they were encrypted via the same process as the others.
After all, if there’s one thing that’s clear from the paper, it’s the importance of luck. That’s not to say what the trio achieved isn’t impressive – it surely is – but as they themselves admit, “if any of the confounding factors had been more extreme (e.g., additional sections, different combinations of transpositions, additional encipherment errors, more unique symbols, etc.), the cipher might still remain unsolved.”
The white paper has been posted to preprint server arXiv.
[H/T: 404 Media]
Source Link: The Second Zodiac Cipher Took 50 Years To Decipher. Now You Can Read How It Was Done