The Zodiac Killer Cipher 2
The Zodiac Killer was a serial killer in the late sixties and maybe early seventies. He sent a number of letters to the press, including four ciphers or cryptograms and only one of them has been solved. The killer's identity remains unknown.
Chris McCarthy has a nice page about the cipher and he also has an ASCII version of the cipher.
Here's a small Ruby hack that calculates the character frequency using the ASCII version of the cipher. Feel free to use it if you like to have a go at cracking it!
EDIT: At this page you can have a go at cracking it real-time. I am not convinced it's really a homophonic substition cipher since the frequency analysis shows that the 340 does not have a flat frequency distribution.
It would be nice to know what cryptographic literature was available for the public in northern California in the late sixties.
Mono-, Bi and Trigram Frequency for English
Hello,
It would be nice to know what cryptographic literature was available for the public in northern California in the late sixties.
I don’t want to seem like a smarta**, but it would have had to be something printed before or during the late 60s. The 408 was a simple substitution cipher. The 340 is most likely a substitution+transposition cipher. The number of permutations to test for this is enormous. I suggest testing in that area.
NewGuy