… I’ve recently taken up the Zodiac cryptograms as sort of a hobby.
I am currently working on the unbroken code, which I’m calling the 340 code since there are 340 characters in it. In the course of trying to get into the head of the Zodiac I’ve examined much (not all) of the material that is available. I did some puliminary work by examining how the Zodiac constructed the 406 code (406 character code that was broken). As you probably well know, he uses several cypher characters for one plaintext character. This convention defeats the use of a letter frequency analysis. To make matters worse, the 340 code is relatively short. A longer code is easier to break since you have a greater sampling of the conventions of the code. That said, I’ve currently moved on to a pattern analysis. I’ve found some interesting patters which I believe will help me identify some words and help me consolidate (equate) some of the encrypted characters. I have not yet broken any plaintext, but I believe it is only a matter of a short time before I make a break through and equate characters to plaintext.

One interesting thing that I believe I’ve discovered, is the meaning of the characters in the last line of the 406 code. To my knowledge, the last part of the code has never been broken. I think I have it. I don’t believe those characters were put there just to fill space, which would be reasonable if he was trying to even out the block. Maybe one or two characters would be used, but not an entire line.

I’ll write more in the future, but I don’t have time right now since I have an engagement in a couple of hours and need to get ready. I’ll share some more of my theories then.