The Masonic cipher: grids, dots and letter enclosures

At first sight it looks like a row of small enclosures: angles, squares open on one side, arrowheads, some marked with a dot. This is the cipher that tradition calls Masonic, known in English as pigpen because of the shape of its signs. It is a simple substitution in which each letter is replaced by the fragment of grid that contains it.

How it is built

The most common scheme uses two noughts-and-crosses grids, that is with nine cells, and two large X shapes. In the first grid and the first X the letters are placed without any mark; in the other two figures the letters are accompanied by a dot. Each letter is represented by the lines bounding its cell: an angle for the corner cells, an open square for the side cells, a closed square for the central one.

The system is easy to memorise, since one need only remember the arrangement of the letters, and the signs are quick to draw. For exactly this reason it offers no security against anyone who knows the scheme, and even without knowing it it is vulnerable to frequency analysis, like every monoalphabetic substitution. Its value lay more in symbolic discretion than in real secrecy.

Kabbalistic roots

The idea of arranging letters in a nine-cell grid is old. In Cornelius Agrippa's De occulta philosophia, published in complete form in 1533, there appears the so-called Kabbalah of nine chambers, in which the Hebrew letters are distributed in a grid and represented by the strokes surrounding them. The scheme, linked to the numerical values of the letters, was known in Jewish tradition as Aiq Bekar.

The transition from the Hebrew to the Latin alphabet took place in the modern era, and various forms of the cipher spread between the seventeenth and eighteenth centuries. It is impossible to name an inventor or a precise date: it is a system that probably circulated in different circles before being adopted by specific groups, which modified it according to their own needs.

In Freemasonry and beyond

In the eighteenth century the cipher was used by Masonic lodges to record certain texts confidentially, which is why it bears their name. Many variants exist, because each group could change the order of the letters. Rosicrucian circles and other associations of the time also adopted similar schemes, valuing their symbolic character more than their cryptographic strength.

One of the best-known examples is in New York, in the churchyard of Trinity Church: the gravestone of James Leeson, who died in 1794, bears an inscription in grid cipher next to Masonic symbols, read according to the usual interpretation as “remember death”. According to various accounts the cipher was also used by prisoners during the American Civil War, and later became a popular game among children and puzzle lovers.

The Masonic cipher shows how a cryptographically weak system can enjoy a long cultural life. Its strength was never secrecy but its ability to turn the alphabet into a set of geometric signs, recognisable to those who belong to a group and mysterious to everyone else, like a language of belonging.