Pigpen cipher

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The pigpen cipher uses graphical symbols assigned according to a key similar to the above diagram.[1]
The pigpen cipher (sometimes referred to as the masonic cipherFreemason's cipher, or tic-tac-toe cipher)[2][3] is a geometric simple substitution cipher, which exchanges letters for symbols which are fragments of a grid. The example key shows one way the letters can be assigned to the grid.


The use of symbols instead of letters is no impediment to cryptanalysis, and this system is identical to that of other simple monoalphabetic substitution schemes. Due to the simplicity of the cipher, it is often included in children's books on ciphers and secret writing.[4]


The exact origin of the cipher is uncertain,[5] but records of this system have been found which go back to at least the 18th century. Variations of this cipher were used by both the Rosicrucian brotherhood[5] and the Freemasons, though the latter used it so often that the system is frequently called the Freemason's cipher. They began using it in the early 18th century to keep their records of history and rites private, and for correspondence between lodge leaders.[3][6][7] Tombstones of Freemasons can also be found which use the system as part of the engravings. One of the earliest stones in Trinity Church Cemetery in New York City, which opened in 1697, contains a cipher of this type which deciphers to "Remember death" (cf. "memento mori"). George Washington's army had documentation about the system, with a much more randomized form of the alphabet. And during the American Civil War, the system was used by Union prisoners in Confederate prisons.[5]


The core elements of this system are the grid and dots. Some systems use the X's, but even these can be rearranged. One commonly used method orders the symbols as shown in the above image: grid, grid, X, X. Another commonly used system orders the symbols as grid, X, grid, X. Another is grid, grid, grid, with each cell having a letter of the alphabet, and the last one having an "&" character. Letters from the first grid have no dot, letters from the second each have one dot, and letters from the third each have two dots. Another variation of this last one is called the Newark Cipher, which instead of dots uses one to three short lines which may be projecting in any length or orientation. This gives the illusion of a larger number of different characters than actually exist.[8]
Another system, used by the Rosicrucians, used a single grid of nine cells, and 1 to 3 dots in each cell or "pen". So ABC would be in the top left pen, followed by DEF and GHI on the first line, then groups of JKL MNO PQR on the second, and STU VWX YZ on the third.[2][5] When enciphered, the location of the dot in each symbol (left, center, or right), would indicate which letter in that pen was represented.[1][5]More difficult systems use a non-standard form of the alphabet, such as writing it backwards in the grid, up and down in the columns,[4] or a completely randomized set of letters.
The Templar cipher is a method claimed to have been used by the Knights Templar. It uses a variant of a Maltese Cross. Alphabet templier.svg


Using the Pigpen cipher key above, the message "X MARKS THE SPOT" is rendered in ciphertext as:
An example pigpen message

In popular culture[edit]

Variation of the Freemason cipher used in the computer gameAssassin's Creed II
The Pigpen cipher has been used in several works of popular culture includingDan Brown's 2009 novel The Lost Symbol, both in the book itself, and also to provide a puzzle in the artwork of the U.S. version of the bookjacket. The Trap, a 2009 nominee for Lancashire Children's Book of the Year, uses a variation of the Pigpen cipher.[9]
Author Clifford B. Hicks included the cipher in his 1963 children's book Alvin's Secret Code, with title character Alvin Fernald explaining its use by Civil War soldiers.
Used in the book The Voyage of the Mimi.
The cover of the Outfield's 1989 album,Voices of Babylon, is written in a pigpen cipher similar to the version shown to the right, as are the song titles in the album's liner notes.
The 39 clues series of popular children's books uses pigpen cipher in many of its puzzles in books and its gaming website.
In the game Assassin's Creed II, a variant of Pigpen is used to provide additional information about the story, in addition to Morse Code and binary code.
In the novel Time Riders: The Doomsday Code, it is used to encrypt a message to the present day from the past.
The BBC series Sherlock has created a website to correlate with the events in the series - The Science of Deduction. Under the "Hidden Messages" tab, "Sherlock" lists three coded messages he received from a stalker, and the third is in pigpen cipher. The message says "Sherlock I have found you".
In Club Penguin, a children's MMO, a modified pigpen cipher is used in the "Secret Agent" aspect of the game.
In the beginning of Linkin Park's "In the End" music video, the doorway that Chester emerges from is inscribed in Pigpen symbols
In the Call of Duty: Black Ops II Zombies map 'Buried', the Pigpen cipher forms part of the quest for players to complete an 'Easter Egg' achievement. Players are required to decipher a code in order to proceed on with the quest. The code uses a cipher based on the letters of the alphabet being grouped into three letters with the corresponding letter being annotated by a line inside the cipher.


  1. Jump up to:a b Wrixon, pp. 182–183
  2. Jump up to:a b Barker, p. 40
  3. Jump up to:a b Wrixon, p. 27
  4. Jump up to:a b Gardner
  5. Jump up to:a b c d e Pratt, pp. 142–143
  6. Jump up^ Kahn, 1967, p.~772
  7. Jump up^ Newton, 1998, p. 113
  8. Jump up^ Glossary of Cryptography
  9. Jump up^ Wray, Sarah (2008). TrapFaber & Faber. pp. 130–131. ISBN 978-0-571-23921-4.


External links[edit]