Pigpen Cipher
The Freemason cipher — symbols instead of letters, used for centuries in secret societies
Why This Matters
The Pigpen cipher — used by Freemasons from at least the 18th century — is one of the most widely recognized symbol ciphers in history. It demonstrates that substituting symbols for letters provides no additional security over substituting other letters.
The Pigpen (or Masonic) cipher uses geometric symbols derived from two grids and two X patterns to represent the 26 letters of the alphabet. It was used by Freemasons from at least the 18th century for lodge records and correspondence. George Washington's Freemason brothers used it; examples appear in gravestone inscriptions and historical documents across the English-speaking world.
The cipher is a simple monoalphabetic substitution using symbols instead of letters — cryptographically equivalent to Caesar or any other fixed letter-to-symbol mapping, and breakable by the same frequency analysis.
The grid layouts: A │ B │ C J │ K │ L ───┼───┼─── ───┼───┼─── D │ E │ F M │ N │ O (dotted versions) ───┼───┼─── ───┼───┼─── G │ H │ I P │ Q │ R S = ╲ T = ╳ U = ╱ (X shapes) V = ╲• W = ╳• X = ╱• (dotted X) Y = ▽ Z = △ (chevrons) The symbol for a letter is the set of grid lines that enclose its cell — nothing more: A = top-left cell → line on the right, line below E = centre cell → all four sides: a closed box H = bottom-middle → left, top and right: open below I = bottom-right → line above, line to the left ...etc — a dot marks the second grid (J–R) (The demo above prints single text characters as stand-ins, because plain text has no glyphs for most of these shapes. The diagram below shows the authentic drawn forms.) Famous users: - Freemasons (lodge records) - George Washington - Civil War soldiers (personal letters)
The Pigpen cipher is a monoalphabetic substitution cipher using symbols instead of letters. Al-Kindi's 850 AD frequency analysis applies directly: count how often each symbol appears, match the most common symbol to E, work through the frequency table, and the alphabet mapping is recovered in minutes. Modern word pattern analysis makes it even faster.
| Concept from Pigpen Cipher | Modern Evolution |
|---|---|
| Symbol substitution | Visual encoding: QR codes, barcodes use symbol-to-data mapping |
| Fixed symbol grid | Character encoding standards: ASCII, Unicode map characters to numbers |
| Secret society use | Need-to-know access control: modern cryptography enforces this mathematically |
| Exhibit | 32 of 140 |
| Era | 18th Century |
| Security | Broken |
| Inventor | Freemasons (popularized) · Earlier origins unknown |
| Year | ~1700s |
| Key Type | Fixed symbol-to-letter grid |
| Broken By | Symbol frequency analysis · Pattern recognition |