Seating Charts, Secret Codes, and History Lessons

Our first gifted classes have been rather fun. Students were assigned seats this year. Each of their names were written in a secret code. It took the class under 3 minutes to figure out exactly where to sit! Great job kids.

Information about Diagrammatic or Pigpen Ciphers

A diagrammatic cipher, used by many children in school, substitutes symbols for letters instead of other letters. This system is, in essence, the same as the letter substitution system, but it's easier to remember than 26 randomly picked letters. It uses the tic-tac-toe boards and two X's as shown below.

The exact origin of the cipher is uncertain, 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 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. 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" 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

Even though it looks like undecipherable outer-space alien text, this would take an arm-chair cryptologist only about 10 minutes or less to figure out. Why? Given enough ciphertext, certain patterns become obvious. Notice how often the empty four-sided box appears: six times out of a total of 29 characters or about 20% of the time. This would immediately indicate that the empty box was almost certainly the symbol for "E," the most frequently used letter in English. Other letters can also be determined by their frequency and by their association with other nearby characters (see "Frequencies"). Almost all substitution ciphers are open to this kind of analysis.