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Zodiac Killer Cipher

Tool to try to understand the Zodiac Killer cipher, still partially unsolved. This code is associated with a killer who sent several letters justifying multiple homicides in the United States.

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Zodiac Killer Cipher -

Tag(s) : Symbol Substitution

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Zodiac Killer Cipher

Zodiac Letters Decryption



Zodiac Letters Encryption





Answers to Questions (FAQ)

What is the Zodiac cipher? (Definition)

The Zodiac cipher is the generic name given to a series of ciphers used by a serial killer in the United States in the 1960s and 1970s. Zodiac is the name given to this serial killer who would be responsible for at least 7 victims in California, USA (according to the authorities/FBI because he claims 37 victims).

Who is the Zodiac killer?

The murderer has never been apprehended and his story has been the subject of numerous reports, documentaries and movies.

What are Zodiac letters?

The Zodiac sent at least 17 letters to local newspapers. These letters sometimes contained evidence of crimes and sometimes cryptograms. It is these 4 cryptograms (called Z408, Z340, Z32 and Z13 depending on their length) made up of symbols that contributed to the mysterious reputation of the killer. The first cryptogram Z408 was resolved quickly. The second cryptogram Z340 was solved in 2020 and the mystery remains unsolved for Z13 and Z32.

How to encrypt a message like the Zodiac cipher?

The Z408 and Z340 messages are homophonic substitution ciphers: the same letter can be encrypted by several different symbols.

Example: A can be encoded by char(55) or char(71) or char(83) in Z408

The Z340 cryptogram also uses a character transposition, resembling a route cipher (reading diagonally).

All other cryptograms use common symbols but do not share the same alphabet and the encryption method may be different.

The letters J, Q, X or Z have no known equivalent in Z408, dCode uses an arbitrary symbol (present in Z340, Z32 or Z13).

The letters J, K, Q', X or Z have no known equivalent in Z340, dCode uses an arbitrary symbol (present in Z408, Z32 or Z13).

How to decrypt a Zodiac-like cipher?

The decryption based on Z408 is that of a homophonic substitution, each character / symbol is associated with a plain letter, and several symbols can be associated with the same letter.

Example: char(53) and char(72) both match T

The decryption based on Z340 is also a homophonic substitution, but the resulting text must then undergo a transposition (mixing of letters). The rule is a diagonal reading (knight moves) in a grid of 17 columns. First letter of the first line, then third letter of the second line, then the 5th letter of the third line, etc.

The cryptograms Z32 or Z13 do not necessarily use the same technique and do not have the same letter-symbol correspondences.

What is the content of Z408?

Crypto Z-408 was sent on July 31, 1969 in 3 pages and was decoded in only 20 hours by a teacher Donald Harden and his wife Bettye. The message was:

char(57)char(37)char(80)char(47)char(90)char(47)char(85)char(66)char(37)char(107)char(79)char(82)char(61)char(112)char(88)char(61)char(66)char(87)char(86)char(43)char(101)char(71)char(89)char(70)char(54)char(57)char(72)char(80)char(64)char(75)char(33)char(113)char(89)char(101)char(77)char(74)char(89)char(94)char(85)char(73)char(107)char(55)char(113)char(84)char(116)char(78)char(81)char(89)char(68)char(53)char(41)char(83)char(40)char(47)char(57)char(35)char(66)char(80)char(79)char(82)char(65)char(85)char(37)char(102)char(82)char(108)char(113)char(69)char(107)char(94)char(76)char(77)char(90)char(74)char(100)char(114)char(92)char(112)char(70)char(72)char(86)char(87)char(101)char(56)char(89)char(64)char(43)char(113)char(71)char(68)char(57)char(75)char(73)char(41)char(54)char(113)char(88)char(56)char(53)char(122)char(83)char(40)char(82)char(78)char(116)char(73)char(89)char(69)char(108)char(79)char(56)char(113)char(71)char(66)char(84)char(81)char(83)char(35)char(66)char(76)char(100)char(47)char(80)char(35)char(66)char(64)char(88)char(113)char(69)char(72)char(77)char(85)char(94)char(82)char(82)char(107)char(99)char(90)char(75)char(113)char(112)char(73)char(41)char(87)char(113)char(33)char(56)char(53)char(76)char(77)char(114)char(57)char(35)char(66)char(80)char(68)char(82)char(43)char(106)char(61)char(54)char(92)char(78)char(40)char(101)char(69)char(85)char(72)char(107)char(70)char(90)char(99)char(112)char(79)char(86)char(87)char(73)char(53)char(43)char(116)char(76)char(41)char(108)char(94)char(82)char(54)char(72)char(73)char(57)char(68)char(82)char(95)char(84)char(89)char(114)char(92)char(100)char(101)char(47)char(64)char(88)char(74)char(81)char(65)char(80)char(53)char(77)char(56)char(82)char(85)char(116)char(37)char(76)char(41)char(78)char(86)char(69)char(75)char(72)char(61)char(71)char(114)char(73)char(33)char(74)char(107)char(53)char(57)char(56)char(76)char(77)char(108)char(78)char(65)char(41)char(90)char(40)char(80)char(122)char(85)char(112)char(107)char(65)char(57)char(35)char(66)char(86)char(87)char(92)char(43)char(86)char(84)char(116)char(79)char(80)char(94)char(61)char(83)char(114)char(108)char(102)char(85)char(101)char(54)char(55)char(68)char(122)char(71)char(37)char(37)char(73)char(77)char(78)char(107)char(41)char(83)char(99)char(69)char(47)char(57)char(37)char(37)char(90)char(102)char(65)char(80)char(35)char(66)char(86)char(112)char(101)char(88)char(113)char(87)char(113)char(95)char(70)char(35)char(56)char(99)char(43)char(64)char(57)char(65)char(57)char(66)char(37)char(79)char(84)char(53)char(82)char(85)char(99)char(43)char(95)char(100)char(89)char(113)char(95)char(94)char(83)char(113)char(87)char(86)char(90)char(101)char(71)char(89)char(75)char(69)char(95)char(84)char(89)char(65)char(57)char(37)char(35)char(76)char(116)char(95)char(72)char(33)char(70)char(66)char(88)char(57)char(122)char(88)char(65)char(68)char(100)char(92)char(55)char(76)char(33)char(61)char(113)char(95)char(101)char(100)char(35)char(35)char(54)char(101)char(53)char(80)char(79)char(82)char(88)char(81)char(70)char(37)char(71)char(99)char(90)char(64)char(74)char(84)char(116)char(113)char(95)char(56)char(74)char(73)char(43)char(114)char(66)char(80)char(81)char(87)char(54)char(86)char(69)char(88)char(114)char(57)char(87)char(73)char(54)char(113)char(69)char(72)char(77)char(41)char(61)char(85)char(73)char(107)

The translation starts with words I like killing people because it is so much fun.

What is the content of Z340?

The Crypto Z-340 was sent on November 8, 1969, it was resolved 51 years later in December 2020 here (link) The message is written in a grid of 17 columns:

char(72)char(69)char(82)char(62)char(112)char(108)char(94)char(86)char(80)char(107)char(124)char(49)char(76)char(84)char(71)char(50)char(100)
char(78)char(112)char(43)char(66)char(40)char(35)char(79)char(37)char(68)char(87)char(89)char(46)char(60)char(42)char(75)char(102)char(41)
char(66)char(121)char(58)char(99)char(77)char(43)char(85)char(90)char(71)char(87)char(40)char(41)char(76)char(35)char(122)char(72)char(74)
char(83)char(112)char(112)char(55)char(94)char(108)char(56)char(42)char(86)char(51)char(112)char(79)char(43)char(43)char(82)char(75)char(50)
char(95)char(57)char(77)char(43)char(122)char(116)char(106)char(100)char(124)char(53)char(70)char(80)char(43)char(38)char(52)char(107)char(47)
char(112)char(56)char(82)char(94)char(70)char(108)char(79)char(45)char(42)char(100)char(67)char(107)char(70)char(62)char(50)char(68)char(40)
char(35)char(53)char(43)char(75)char(113)char(37)char(59)char(50)char(85)char(99)char(88)char(71)char(86)char(46)char(122)char(76)char(124)
char(40)char(71)char(50)char(74)char(102)char(106)char(35)char(79)char(43)char(95)char(78)char(89)char(122)char(43)char(64)char(76)char(57)
char(100)char(60)char(77)char(43)char(98)char(43)char(90)char(82)char(50)char(70)char(66)char(99)char(121)char(65)char(54)char(52)char(75)
char(45)char(122)char(108)char(85)char(86)char(43)char(94)char(74)char(43)char(79)char(112)char(55)char(60)char(70)char(66)char(121)char(45)
char(85)char(43)char(82)char(47)char(53)char(116)char(69)char(124)char(68)char(89)char(66)char(112)char(98)char(84)char(77)char(75)char(79)
char(50)char(60)char(99)char(108)char(82)char(74)char(124)char(42)char(53)char(84)char(52)char(77)char(46)char(43)char(38)char(66)char(70)
char(122)char(54)char(57)char(83)char(121)char(35)char(43)char(78)char(124)char(53)char(70)char(66)char(99)char(40)char(59)char(56)char(82)
char(108)char(71)char(70)char(78)char(94)char(102)char(53)char(50)char(52)char(98)char(46)char(99)char(86)char(52)char(116)char(43)char(43)
char(121)char(66)char(88)char(49)char(42)char(58)char(52)char(57)char(67)char(69)char(62)char(86)char(85)char(90)char(53)char(45)char(43)
char(124)char(99)char(46)char(51)char(122)char(66)char(75)char(40)char(79)char(112)char(94)char(46)char(102)char(77)char(113)char(71)char(50)
char(82)char(99)char(84)char(43)char(76)char(49)char(54)char(67)char(60)char(43)char(70)char(108)char(87)char(66)char(124)char(41)char(76)
char(43)char(43)char(41)char(87)char(67)char(122)char(87)char(99)char(80)char(79)char(83)char(72)char(84)char(47)char(40)char(41)char(112)
char(124)char(70)char(107)char(100)char(87)char(60)char(55)char(116)char(66)char(95)char(89)char(79)char(66)char(42)char(45)char(67)char(99)
char(62)char(77)char(68)char(72)char(78)char(112)char(107)char(83)char(122)char(90)char(79)char(56)char(65)char(124)char(75)char(59)char(43)

The message begins with I hope you are having lots of fun to catch me

It is again a homophonic substitution but this time, the letters of the message have been transposed so as to read diagonally on 9 lines: the reading order is:

110192837465564738291100109118127136145
137146211202938475665748392101110119128
120129138147312213039485766758493102111
103112121130139148413223140495867768594
869510411312213114014951423324150596877
697887961051141231321411506152433425160
526170798897106115124133142151716253443
354453627180899810711612513414315281726
182736455463728190991081171261351441539
154163172181190199208217226235244301302303304305306
285293155164173182191200209218227236245253261269277
270278286294156165174183192201210219228237246254262
255263271279287295157166175184193202211220229238247
239248256264272280288296158167176185194203212221230
222231240257265273281289297159168177186195204213249
205214223232241250258266274282290298160169178187196
188197206215224233242251259267275283291299161170179
171180189198207216225234243252260268276284292300162
310309308307311312313314316315318317319320321322325
324323327326335334333332331330329328336337338339340

What is the content of Z13?

Crypto Z-13 is dated April 20, 1970, it is the shortest, it is preceded by MY NAME IS which suggests that the killer could reveal its identity. The message is:

char(65)char(69)char(78)char(122)char(48)char(75)char(48)char(77)char(48)char(91)char(78)char(65)char(77)

What is the content of Z32?

The crypto Z-32 was sent on June 26, 1970, it was accompanied by a map of the San Francisco Bay.

char(67)char(57)char(74)char(124)char(35)char(79)char(107)char(91)char(65)char(77)char(102)char(56)char(63)char(79)char(82)char(84)char(71)char(88)char(54)char(70)char(68)char(86)char(106)char(37)char(72)char(67)char(69)char(76)char(122)char(80)char(87)char(57)

The investigators assume that this cryptogram may contain numerical geographic coordinates.

What are the common points between Z408 and Z340?

By having deciphered 2 of the messages, a hope of understanding the last 2 arose. Unfortunately, although the symbols are similar, the transliterations common to the two cryptograms are rare. Here are the symbols and their correspondences:

z408z340z408z340z408z340z408z340
char(65)WDchar(66)LEchar(67)Ychar(68)NN
char(69)ERchar(70)SFchar(71)ATchar(72)TI
char(73)Tchar(74)FSchar(75)SAchar(76)TG
char(77)HOchar(78)EEchar(79)NAchar(80)II
char(81)Fchar(82)GOchar(83)ADchar(84)OR
char(85)ISchar(86)BOchar(87)EWchar(88)OR
char(89)UNchar(90)ERchar(98)Echar(99)VE
char(100)OLchar(101)CXchar(102)DBchar(106)P
char(107)IIchar(108)AAchar(112)ECchar(113)MU
char(114)RZchar(116)RLchar(121)Ichar(122)DA
char(33)Ochar(35)LTchar(37)LTchar(38)IS
char(40)NTchar(41)HWchar(42)LAchar(43)EH
char(45)Schar(46)Nchar(47)KUchar(48)
char(49)Rchar(50)Mchar(51)Ychar(52)E
char(53)TVchar(54)EDchar(55)ALchar(56)SP
char(57)INchar(58)Tchar(59)Tchar(60)I
char(61)PQchar(62)Nchar(63)Jchar(64)SU
char(91)char(92)RKchar(94)NOchar(95)YB
char(124)E

There are only 5 symbols with a common key: char(68) (=N), char(107) (=I), char(108) (=A), char(78) (=E), char(80) (=I).

The symbol in Z13 char(91) do not appear in any of these 2 decrypted messages.

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