Tuesday, October 25, 2011

Blog: How Revolutionary Tools Cracked a 1700s Code

How Revolutionary Tools Cracked a 1700s Code
New York Times (10/25/11) John Markoff

A cipher dating back to the 18th century that was considered uncrackable was finally decrypted by a team of Swedish and U.S. linguists by using statistics-based translation methods. After a false start, the team determined that the Copiale Cipher was a homophonic cipher and attempted to decode all the symbols in German, as the manuscript was originally discovered in Germany. Their first step was finding regularly occurring symbols that might stand for the common German pair "ch." Once a potential "c" and "h" were found, the researchers used patterns in German to decode the cipher one step at a time. Language translation techniques such as expected word frequency were used to guess a symbol's equivalent in German. However, there are other, more impenetrable ciphers that have thwarted even the translators of the Copiale Cipher. The Voynich manuscript has been categorized as the most frustrating of such ciphers, but one member of the team that cracked the Copiale manuscript, the University of Southern California's Kevin Knight, co-published an analysis of the Voynich document pointing to evidence that it contains patterns that match the structure of natural language.

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