Zodiac Killer Ciphers Wiki - User contributions [en]

Solved 340-character cipher (old version)

2015-05-25T10:39:28Z

Jarlve: /* Transpositions and other possible variations */

__FORCETOC__
Zodiac, the serial killer who terrorized Northern California in the late 1960s, sent four ciphers to local newspapers. The first cipher was separated into three different parts and each part was sent to Vallejo Times-Herald, the San Francisco Chronicle, and the San Francisco Examiner. The combination of all three parts formed a 408-letter cipher, which was decrypted one week after it was received. Zodiac also sent a 340-letter cipher, mailed on a card on November 8 1969, that remains unsolved to this day.

== Articles and information about the 340 cipher ==

[[File:340-cipher-hi-resolution.jpg|thumb|High-resolution scan of the 340-character cipher]]
[[File:Sfchron340cipher.png|thumb|Cipher as it appeared in the SF Chronicle on Nov 13, 1969 (Credit: Deborah Silva, who posts as Seagull on the Zodiac forums)]]

*[[Encyclopedia of observations]] - A collection of observations about the cipher text
*[[Comparison of cipher alphabets]]
*[[Comparison of character repetition rates]]
*[[Comparison of sequence repetition rates]]
*[[Levenshtein distance analysis]] - A look at the occurrences of repeated sequences that are not exact matches.
*[[Quadrant analysis]] - Do the n-gram counts improve If we split the cipher text into four quadrants?
*[[Quadrant analysis Part 2]] - An expansion of the previous quadrant analysis experiment. Is it possible to produce quadrant arrangements that increase the number and quality of homophones detected algorithmically?
*Information theory (entropy, randomness, etc)
*[[FBI analysis from Dan Olson]]
*[[Cipher-related excerpts from case documents]]
*[[Word frequency analysis]] (word frequencies derived from a corpus of Zodiac correspondences)
*[http://www.zodiackillerfacts.com/forum/viewtopic.php?f=50&t=1339 Omnidirectional repetitions] - An investigation into patterns that repeat in arbitrary directions by following "snake-like" paths.
*[http://www.zodiackillerfacts.com/forum/viewtopic.php?p=23179#p23179 "Complexification"] - Did the cipher author begin with a simpler set of cipher symbols, then "complexify" certain symbols to further flatten the symbol distributions?
*[[Substring ranking]] - Can we apply measurements that give us a way to find interesting sections of cipher text for focused attacks?
*[[Catalog of repeating fragments]] - A comprehensive list of portions of cipher text that occur more than once in the cipher text.
*[[Cipher Legitimacy]] - Are the Zodiac ciphers real, or are they hoaxes?
*[[Corpus Experiments]] - A collection of corpus-based experiments performed on the Zodiac ciphers

== Homophone sequences ==
* Detection of homophone sequences in the cipher text
**[http://www.zodiackillerfacts.com/forum/viewtopic.php?f=50&t=1329&p=22906 Jurgen Koller's "Two-Times Repetition" approach]
**[http://www.zodiackillerfacts.com/forum/viewtopic.php?f=50&t=1329&p=22906#p22906 Computation of statistical significance of 6-symbol repetitions at the beginning of the cipher text]
**[[Brute force search for homophone sequences]] - Shows sequences detected in the 408 and 340 ciphers by performing brute force searches for sequences involving up to 7 symbols.

== The "Pivots" ==
*[http://www.zodiackillerfacts.com/forum/viewtopic.php?p=22455#p22455 Reversible trigram patterns in the intersecting "pivots" of the cipher text]
*[http://www.zodiackillerfacts.com/forum/viewtopic.php?f=11&t=1282&p=21758#p21758 Experiment to estimate odds of two intersecting "pivots" occurring by chance]
*[http://zodiackillerciphers.com/wiki/index.php?title=Pivots Experimental results of generating pivots from large collection of plain text]

== Transpositions and other possible variations ==
Is the 340 cipher unsolved because it is not a simple homophonic substitution cipher like the 408 cipher? Here is a collection of considered possibilities:
*[[Oxcart]] - Does the 340 cipher's plaintext follow an "ox cart" path; that is, does it read alternately from left to right, then right to left?
*Vigenere
**[http://www.zodiackillerfacts.com/forum/viewtopic.php?f=50&t=1230 Vigenere encipherment prior to homophonic substitution]
*Playfair
**[http://www.zodiackillerfacts.com/forum/viewtopic.php?p=20902#p20902 Playfair encipherment prior to homophonic substitution]
*Bifid
**[http://www.zodiackillerfacts.com/forum/viewtopic.php?p=22038#p22038 Bifid encipherment prior to homophonic substitution]
*Did the killer encipher the message, then [http://www.zodiackillerfacts.com/forum/viewtopic.php?p=24969#p24969 re-arrange its lines?]
*Many-to-many (one cipher symbol maps to multiple plaintext letters)
*Multiple encryption stages (examples: homophonic that has been rehomophoned, homophonic that has been transposed)
*Phonetic / nomenclator
*Was the cipher intended for use [http://www.zodiackillerfacts.com/forum/viewtopic.php?f=50&t=1390&start=20#p24191 by its author only?]
*[http://www.zodiackillersite.com/viewtopic.php?f=81&t=2435 Jarlve's tests]
**At the above link, Jarlve has documented the following variations: Cardan grille variant, stacked directional transformations, spirals and double spirals.

== Halloween Card ==
* Does the Halloween Card, mailed by the killer a year after the 340 cipher, contain clues about the 340?
**[http://www.kirps.com/web/main/resources/various/zodiac340/ Jos Kirps' article about interesting coincidences between the Halloween card and the 340 cipher]

Encyclopedia of observations

2015-05-22T09:46:58Z

Jarlve: /* 408-character cipher observations */

TODO - work in progress

This page is meant to collect the many factual observations people have made about the ciphers over the years.

=408-character cipher observations=
* Several symbol/letter assignments in the 408 key seem to reflect adjacencies on QWERTY-layout keyboards (the standard keyboard layout for typewriters and computer keyboards). [http://www.zodiackillersite.com/viewtopic.php?f=81&t=2419 (Source)]

=340-character cipher observations=
* The paper the cipher is written on contains several [http://oranchak.com/340-5th-avenue.jpg Fifth Avenue watermarks] (here's [http://zodiackillerciphers.com/images/i1x1W.gif glurk's animation] to help you spot where they appear).
* The first 3 symbols of the 340 do not reappear soon. It starts with "HER", and H only appears 3 other times, E only appears 2 other times. (From [http://www.zodiackillerfacts.com/forum/viewtopic.php?p=24573#p24573 Duman])
* In the third column, the 3 occurrences of the "R" symbol are evenly spaced, each separated by four rows. (From [http://www.zodiackillerfacts.com/forum/viewtopic.php?p=22619#p22619 Wrench])
* The author of the cipher does not use the forward-facing letter Q as a cipher symbol, but uses a backwards-facing Q instead. Similarly, he does not use the forward-facing letter C as a cipher symbol in the 408-character cipher, but uses a backwards-facing C instead. Why doesn't he use up all the normal alphabetic symbols before resorting to additional symbols and variations?
* The first repeated symbol occurs at the 19th position. Thus the first 18 symbols contain no repeats. Coincidentally, the last 18 symbols of the 408 cipher do not form a legible solution. (From [http://www.zodiackillerfacts.com/forum/viewtopic.php?p=24901#p24901 traveller1st])
* The most frequently occurring symbol, +, occurs 24 times. Only once does it fall on a prime-numbered position in the cipher text (counting from 1 to 340), against expectations. [http://www.zodiackillerciphers.com/?p=319 (More detail)] [http://zodiac340.blogspot.com/2013/03/zodiac-primes.html (From Dan Johnson)]
* The second most frequently occurring symbol, B, occurs 12 times. Only once does it fall on a prime-numbered position in the cipher text (counting from 1 to 340), against expectations. [http://www.zodiackillerciphers.com/?p=319 (More detail)] [http://zodiac340.blogspot.com/2013/03/zodiac-primes.html (From Dan Johnson)]
* The upper loop of the "B" symbol on line 19 column 9 is larger than the lower loop, making the symbol look disproportional and distinct from the other "B" symbols. (From Doc. Doc also speculates the symbol was original a "P" and the author corrected it by adding the bottom loop.)
* The last occurrence of the "+" symbol is wider than the others. (From Doc. Doc speculates that the author "hesitated" on this symbol.)
* Cipher symbols seem to get larger as the cipher goes on. Row 20 seems larger than Row 1. (From Doc. Doc speculates the author wrote the cipher from top to bottom, and was tiring.)
* The backwards D at the end of the first line [http://zodiackillerciphers.com/images/z340-d-dot-line-1.png appears to have a dot in it] (Source: [http://boxofrain.wordpress.com/2007/08/12/zodiac-killers-unsolved-340-symbol-cipher/#comment-6572 comment from "The McNX"])
* The symbols that represent "R" in the 408 are [[File:br.jpg]] and [[File:backslash.jpg]]. Both symbols are missing from the 340 cipher. (Source: [http://zodiackillersite.com/viewtopic.php?p=9091#p9091 Wier])

= 408 and 340 =
* "The 408 and 340 ciphers fit exactly into two standard-size pages ruled into half-inch squares. The 408 will use one page plus one inch from another page. The second page will then fit the 340 exactly." (from [http://www.zodiackillersite.com/viewtopic.php?f=81&t=296 Jem]) (Open question: Is the 340 a continuation of the 408?)
* "An 8 1/2 X 11 inch paper divided into 1/2" squares yields 17X22 or 374 separate squares. Two pages together: 374 X 2= 748. The two ciphers together? 748 symbols." (from [http://www.zodiackillersite.com/viewtopic.php?f=81&t=296 entropy])

User:Jarlve

2015-05-17T17:06:43Z

Jarlve: Created page with "== Test page =="

== Test page ==