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Codebreakers decipher 300-year-old secret

USC (US) — Scientists have cracked the code of a 300-year-old, 75,000-character manuscript that is handwritten in abstract symbols and Roman letters and fills 105 pages.

The mysterious “Copiale Cipher” cryptogram, bound in gold and green brocade paper and found hidden in the depths of an academic archive, reveals the rituals and political leanings of an 18th-century secret society in Germany. The rituals detailed in the document indicate the secret society had a fascination with eye surgery and ophthalmology, though it seems members of the secret society were not themselves eye doctors.

“This opens up a window for people who study the history of ideas and the history of secret societies,” says research professor of computer science at the University of Southern California, who was part of an international team that finally cracked the manuscript’s code.

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“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.”

To break the Copiale Cipher, Knight and colleagues Beáta Megyesi and Christiane Schaefer of Uppsala University in Sweden tracked down the original manuscript, which was found in the East Berlin Academy after the Cold War and is now in a private collection. They then transcribed a machine-readable version of the text, using a computer program created by Knight to help quantify the co-occurrences of certain symbols and other patterns.

“When you get a new code and look at it, the possibilities are nearly infinite,” Knight says. “Once you come up with a hypothesis based on your intuition as a human, you can turn over a lot of grunt work to the computer.”

With the Copiale Cipher, the codebreaking team began not even knowing the language of the encrypted document. But they had a hunch about the Roman and Greek characters distributed throughout the manuscript, so they isolated these from the abstract symbols and attacked it as the true code.

“It took quite a long time and resulted in complete failure,” Knight says. After trying 80 languages, the cryptography team realized the Roman characters were “nulls,” intended to mislead the reader. It was the abstract symbols that held the message.

The team then tested the hypothesis that abstract symbols with similar shapes represented the same letter, or groups of letters. Eventually, the first meaningful words of German emerged: “Ceremonies of Initiation,” followed by “Secret Section.”

Knight is now targeting other coded 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 the software to other famous unsolved codes including the last section of  “Kryptos,” an encrypted message carved into a granite sculpture on the grounds of CIA headquarters, and the Voynich Manuscript, a medieval document that has baffled professional cryptographers for decades.

But for Knight, the trickiest language puzzle of all is still everyday speech. “Translation remains a tough challenge for artificial intelligence.”

With researcher Sujith Ravi, who received a PhD in computer science from USC in 2011, Knight has been approaching translation as a cryptographic problem, which could not only improve human language translation but could also be useful in translating languages that are not currently spoken by humans, including ancient languages and animal communication.

The National Science Foundation funds Knight’s cryptography and translation research. The Copiale Cipher work was presented as part of an invited presentation at the 2011 Association for Computational Linguistics meeting.

More news from USC: http://uscnews.usc.edu/

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