The Copiale Cipher

Few ciphers have a more bizarre past than the Copiale Cipher, which was used by a clandestine organization known as the Oculist Order. Despite none of the members being surgeons, they all had a real thing for eye surgery. There's nothing odd about that!

The cipher has been around since perhaps about 1760–1780. The Copiale cipher is a 105-page bound volume containing a 75,000 handwritten character encrypted document. The manuscript, which had remained untranslated for more than 260 years, was decrypted in 2011 with the aid of cutting-edge computer methods.

The cipher was discovered to be an encrypted German text by a global team that included Kevin Knight from the University of Southern California Information Sciences Institute and USC Viterbi School of Engineering, as well as Beáta Megyesi and Christiane Schaefer from Uppsala University in Sweden.

The text and spaces in the document are encoded using a homophonic cipher that employs a sophisticated substitution system that includes both symbols and letters. It took a long time for code breakers to figure it out, and they eventually realized that the Roman letters weren't actually part of the words being translated but were only there to be deceptive.