The Masonic cipher: grids, dots and hidden letters

Two grids like those of noughts and crosses, two X-shaped crosses and a few dots: with these few elements one of the best-known ciphers in history is built, the so-called Masonic cipher. In English it is called pigpen, because the signs resemble small pens. Each letter is replaced by the portion of the grid in which it lies, with or without a dot, and the message takes on the appearance of a row of angles and squares.

The roots in the Kabbalah of nine chambers

The principle on which the cipher rests is older than Freemasonry. In the De occulta philosophia, published in full in 1533, Heinrich Cornelius Agrippa describes a method known as the Kabbalah of nine chambers, or Aiq Bekar from the first Hebrew letters it contains. The twenty-two Hebrew letters and the five final forms are distributed over a grid of nine cells, three per cell, according to their numerical value.

In that context the grid did not serve to hide messages, but to derive signs and seals from the names of spirits and angels: the shape of the cell became a magical character. The passage from Kabbalistic tool to cipher system happened gradually, and various kinds of grids for replacing letters were already circulating among scholars of the sixteenth and seventeenth centuries.

In the eighteenth-century lodges

Modern Freemasonry was officially born in London in 1717, with the founding of the first Grand Lodge. During the century the lodges developed a rich heritage of symbols, degrees and ceremonies, and confidentiality was one of their fundamental values. The grid cipher was adopted in various Masonic settings, particularly in the Royal Arch degree, to write words and notes to be kept private.

From a security point of view, the Masonic cipher is very weak. It is a simple monoalphabetic substitution, which can be solved by analysing letter frequencies, a technique already described in the ninth century by the Arab philosopher al-Kindi. Its function was symbolic rather than technical: it marked membership of a community and distance from the profane world.

A gravestone in New York

One of the best-known examples of the Masonic cipher is found in the churchyard of Trinity Church, in Manhattan. The gravestone of James Leeson, who died in 1794 and was a Freemason, bears at the top an inscription in grid characters. Once deciphered, it reveals a brief admonition to remember death, a traditional theme of funerary art. Other similar inscriptions are found on tombs and monuments of the eighteenth and nineteenth centuries.

During the nineteenth century the cipher left the lodges and became popular among young people and in books of games, because it is easy to learn and pleasant to draw. Even today it appears in novels, video games and treasure hunts, often presented as a secret code of the Freemasons. During the American Civil War, according to some accounts, it was also used by prisoners and soldiers for brief messages, although its weakness made it ill-suited to serious military use.

The history of the Masonic cipher is a small example of how an idea can change function over time. Born as a Kabbalistic tool for turning names into seals, Agrippa's grid became a sign of initiatory belonging and finally a game, without losing the charm of hidden writing. Few codes are so simple and, at the same time, so laden with history.