The Pigpen cipher is a simple substitution cipher that was used by the Freemasons in the 18th century. It involves substituting letters for symbols. The key to understanding the symbols is shown below,
The lines and dots in the vicinity of each letter make up the symbol that is used to encrypt it. The following is the Pigen encryption of the word SECRET.
Programming The Cipher
This one is a little trickier than the other ciphers. We can't just do some intelligent Maths with the character codes or swap one letter for another.
Here is a screenshot from a program that generates Pigpen cipher text as an exportable image,