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The Zodiac Ciphers
What do we know? And
when can we stop trying
to solve them?
David Oranchak
http://zodiackillerciphers.c...
December 20, 1968
Betty Lou Jensen, David Faraday
Lake Herman Road, Benicia
July 4, 1969
Darlene Ferrin, Michael Mageau
Bl...
The Ciphers
Z408 Z340
Z32
Z13
13 symbols long
8 unique symbols in cipher alphabet
Names Phrases
Cipher is 32 symbols long
But there are 29 unique symbols!
I like killing people
because it is so much fun
it is more fun than killing
wild game in the forrest
because man is the mo...
EBEORIETEMETHHPITI
ROBE[R]T EM[M]ET THE HIP[P]IE
TIMOTHIE E. PHEIBERTE
I'M HERE TO BITE THE PIE
THE EERIE POET BIT HIM
I H...
EBEORIETEMETHHPITI
ROBE[R]T EM[M]ET THE HIP[P]IE
TIMOTHIE E. PHEIBERTE
I'M HERE TO BITE THE PIE
THE EERIE POET BIT HIM
I H...
PART
1:
PART
2:
Symbols in Z408 alphabet, not
in Z340 alphabet:
Symbols in Z340 alphabet, not
in Z408 alphabet:
Z408 Z340
8.5” 8.5”
11”
11”
8.5” 8.5”
11”
11”
62 repeats 25 repeats
11 repeats 2 repeats
Distance 19:
37 repeated bigrams
Distance 14, reading
right to left:
40 repeated bigrams
Distance 1:
25 repeated bigrams
7 occurrences 6 occurrences
Plaintexts with
similar patterns:
1.5%
Chance of
preserving during
encipherment:
1 in 50,000
Prime positions:
2, 3, 5, 7, 11, 13, 17, 19,
23, 29, 31, 37, 41, 43, 47,
53, 59, 61, 67, 71, 73, 79,
83, 89, 97, 101, 103,...
ODDS
EVENS
When can we stop trying to solve it?
● Someone solves it
● No message to find
● Better things to do
But we want to know th...
“Z340 was made like Z408” hypothesis
● Homophonic substitution
● Normal reading direction
● English language
● Possible mi...
“Symbol confusion”
groups
Cipher generator
● Big pile of books
● Take random samples of length 340
● Generate random missp...
Sample generated ciphers -
Patterns similar to Z340
Gilbert and
Sullivan
Count of Monte
Cristo
Les Miserables
Z340 Generated
● Improve codebreaking skills
○ Some plaintexts are harder than others
● Verify that hypothesis can make Z340-like
cipher
...
Explore other hypotheses
● Dan Olson’s hypothesis
● Transpositions
● Wildcards/polyphones
● Ngram substitution
● Quadrants...
Future Work:
● Continue collecting observations, test results, and ruling out hypotheses
● Knight/Nuhn’s cipher type detec...
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
The Zodiac Ciphers: What do we know?  And when can we stop trying to solve them?
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The Zodiac Ciphers: What do we know? And when can we stop trying to solve them?

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Slides from my recent talk at the 2015 Cryptologic History Symposium in Laurel, MD

Published in: Data & Analytics
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The Zodiac Ciphers: What do we know? And when can we stop trying to solve them?

  1. 1. The Zodiac Ciphers What do we know? And when can we stop trying to solve them? David Oranchak http://zodiackillerciphers.com
  2. 2. December 20, 1968 Betty Lou Jensen, David Faraday Lake Herman Road, Benicia July 4, 1969 Darlene Ferrin, Michael Mageau Blue Rock Springs Park, Vallejo September 27, 1969, Cecelia Shepard, Bryan Hartnell Lake Berryessa October 11, 1969 Paul Stine Presidio Heights, San Francisco
  3. 3. The Ciphers Z408 Z340 Z32 Z13
  4. 4. 13 symbols long 8 unique symbols in cipher alphabet
  5. 5. Names Phrases
  6. 6. Cipher is 32 symbols long But there are 29 unique symbols!
  7. 7. I like killing people because it is so much fun it is more fun than killing wild game in the forrest because man is the most dangerous animal of all to kill something gives me the most thrilling experience it is even better than getting your rocks off with a girl the best part of it is that when I die I will be reborn in paradice and all the I have killed will become my slaves I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife ebeorietemethhpiti
  8. 8. EBEORIETEMETHHPITI ROBE[R]T EM[M]ET THE HIP[P]IE TIMOTHIE E. PHEIBERTE I'M HERE TO BITE THE PIE THE EERIE POET BIT HIM I HOE THE TIBET EMPIRE I BETTER HOPE I TEE HIM. BE HERE. TIPTOE. TIE HIM.
  9. 9. EBEORIETEMETHHPITI ROBE[R]T EM[M]ET THE HIP[P]IE TIMOTHIE E. PHEIBERTE I'M HERE TO BITE THE PIE THE EERIE POET BIT HIM I HOE THE TIBET EMPIRE I BETTER HOPE I TEE HIM. BE HERE. TIPTOE. TIE HIM.
  10. 10. PART 1: PART 2:
  11. 11. Symbols in Z408 alphabet, not in Z340 alphabet: Symbols in Z340 alphabet, not in Z408 alphabet:
  12. 12. Z408 Z340
  13. 13. 8.5” 8.5” 11” 11”
  14. 14. 8.5” 8.5” 11” 11”
  15. 15. 62 repeats 25 repeats
  16. 16. 11 repeats 2 repeats
  17. 17. Distance 19: 37 repeated bigrams Distance 14, reading right to left: 40 repeated bigrams Distance 1: 25 repeated bigrams
  18. 18. 7 occurrences 6 occurrences
  19. 19. Plaintexts with similar patterns: 1.5% Chance of preserving during encipherment: 1 in 50,000
  20. 20. Prime positions: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337
  21. 21. ODDS EVENS
  22. 22. When can we stop trying to solve it? ● Someone solves it ● No message to find ● Better things to do But we want to know the solution, so we keep trying. Most commonly tested idea: Z340 was made like Z408. A better question is: When can we move on to another idea? Possible answer: Generate many test ciphers
  23. 23. “Z340 was made like Z408” hypothesis ● Homophonic substitution ● Normal reading direction ● English language ● Possible misspellings ● Omitted words ● Possible transcription errors ● Curious features are random accidents ● Filler
  24. 24. “Symbol confusion” groups Cipher generator ● Big pile of books ● Take random samples of length 340 ● Generate random misspellings, omissions, filler ● Generate random keys ● Measure features ○ Symbol counts, ngram count, appearances of cycles, prime phobia, transcription errors, even/odd discrepancy, row randomness, appearances of specific patterns, filler section, misspellings ● Use multiobjective optimization to find keys with measurements most similar to Z340 ○ Genetic algorithm
  25. 25. Sample generated ciphers - Patterns similar to Z340 Gilbert and Sullivan Count of Monte Cristo Les Miserables
  26. 26. Z340 Generated
  27. 27. ● Improve codebreaking skills ○ Some plaintexts are harder than others ● Verify that hypothesis can make Z340-like cipher ● Curious features may be phantoms ● Solving numerous test ciphers increases confidence that hypothesis is wrong. Nice parlor trick. But what’s the point?
  28. 28. Explore other hypotheses ● Dan Olson’s hypothesis ● Transpositions ● Wildcards/polyphones ● Ngram substitution ● Quadrants ● Home-grown modification to simple substitution ● Error in encipherment method ● And an infinite number of others
  29. 29. Future Work: ● Continue collecting observations, test results, and ruling out hypotheses ● Knight/Nuhn’s cipher type detection ○ Obtain/generate huge training set of ciphers ○ Better results are possible with ensemble classifiers ○ Example: “Netflix Prize” won by BellKor’s Pragmatic Chaos classifier ● How would Z340 be classified? ● Online workbench: Centralize autosolvers and statistical tools More Info: ZodiacKillerCiphers.Com Thanks to: The many researchers and collaborators in the forums at ZodiacKillerSite. com, ZodiacKillerFacts.com, and ZodiacKiller.com.

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