Washington: More than three centuries after it was written, scientists have now managed to decipher a mysterious encrypted manuscript of a secret society that used abstract symbols and Roman letters meticulously to mislead readers.

The enciphered message revealed the rituals and political aims of an enigmatic 18th-century German fellowship, the "Oculist Order", disclosing the society had a fascination with eye surgery, though it seems members of the society were not eye doctors.

"This opens up a window for people who study the history of ideas and the history of secret societies," said researcher Kevin Knight, a computer scientist at the University of Southern California.

"Historians believe that secret societies have had a role in revolutions, but all that is yet to be worked out, and a big part of the reason, is because so many documents are enciphered," Knight was quoted as saying by a portal.

The mysterious cryptogram, bound in gold-and-green brocade paper, dates back to a time between 1760 and 1780.

Once hidden in the depths of the East Berlin Academy and uncovered after the Cold War, its 75,000 characters are written in 90 different cipher letters, including the 26 Roman letters as well as many abstract symbols.

On its 105 yellowing pages, the only plain text is "Philipp 1866" on the flyleaf and "Copiales 3" at the end of the last page. "Philipp" is thought to have been an owner of the manuscript, while "Copiales" was used to give the secret writing its name: the Copiale Cipher.

To break the cipher, an international team of researchers tracked down the manuscript, now in a private collection, and transcribed a machine-readable version of the text.

After trying 80 languages, the cryptography team realized the Roman characters were "nulls" intended to mislead readers.

"It was exciting to decode," Knight said. "This may help trace the development of political ideas and the advancement of ranks within secret societies."

The scientists, who detailed their work at a meeting of the Association for Computational Linguistics in Portland Ore, are now targeting other encrypted messages, including ciphers sent by the Zodiac Killer, a serial murderer who sent taunting messages to the press and has never been caught.

Knight is also applying his computer-assisted decryption software to other famous unsolved codes such as the last section of "Kryptos" -- an encrypted message carved into a granite sculpture on the grounds of the CIA headquarters, and the Voynich Manuscript, a medieval document that has baffled professional cryptographers for decades.