Dave Oranchak posted today about how he (along with Jarlve and Sam Blake) cracked the Zodiac Killer’s infamous Z340 cipher. Here’s his video:
Unsurprisingly (to me), it turned out that code breakers had been (kind of) close for some time, with the single largest tell (than never quite told) being the curious results you get if you examine every 19th character of the Z340.
So, the core of the cipher system turned out to be a combination of a “knight move” transposition (down one row and along two columns) plus the Zodiac Killer’s trademark set of reflected letter shapes.
However, Zodiac – clearly stung by the ease with which his first major cipher had been cracked – threw in some extra confounding factors.
- At the end of the top line, he wrote the words “LIFE IS” in his homophonic cipher (not transposed)
- At the end of the bottom line, he wrote the word “DEATH” in his homophonic cipher (also not transposed)
- The rest of the bottom two lines were written in his homophonic cipher, but with the letter-order of some of the words reversed (e.g. the Zodiac’s signature word “PARADICE” was written as “ECIDARAP”)
- The remainder of the cipher was split into two nine-line blocks, where the order of the letters was transposed using knight’s move reordering.
There was also, annoyingly, a single row of ciphered letters in the middle that were out by a single column, which skewed all the text passing through it. It’s fairly easy to see that once you’ve got everything else right, though.
This was – I hope you’ll agree – a simply epic slab of codebreaking. Congratulations to David Oranchak, Sam Blake, and Jarl Van Eycke!!!!
All in all, the Z340 plaintext reads:
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
WILL BE AN EASY ONE IN PARADICE
LIFE IS DEATH