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Old Cipher Broken
Topic Started: Jul 3 2009, 01:54 AM (1,909 Views)
Gerry StPierre
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Interesting article about an old cipher sent to Thomas Jefferson by one of his correspondents. It has been solved by a math professor at UPenn.
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mosher
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Hi Gerry,

Great link to a very interesting article -- thanks! As far as I can tell, Dr. Smithline's article "A Cipher to Thomas Jefferson" (American Scientist. 2009) has not been published in Cryptologia, so that explains why many of us are not aware of it.

Did Dr. Smithline know what the underlying system was? Even if he did, this would not detract from the ingenuity of finding the precise sequence of 2-digit numbers. A computer, however, could run through all possible combinations in a relatively short amount of time.

In David Kahn "The Codebreakers" (5th edition, 1967) page 194 there are references that indicate that the cipher system was publicly known:

Quote:
 
Morever, on March 22, 1802, he wrote Dr. Patterson, who had submitted a cipher to Jefferson as President of the American Philosophical Society, that "I have thoroughly considered your cypher, and find it so much more convenient than my wheel cypher, that I am proposing it to the Secretary of state for use in his office," a month later adding that "We are introducing your cypher into our foreign correspondences." Patterson's cipher was a columnar transposition with nulls at the heads of the columns, of a security in no way comparable to Jefferson's. That Jefferson did not see this does not speak too highly of his cryptologic perceptions.


Kahn references Patterson's cipher as found in Jefferson's Papers, ff. 20446-9.

Summarizing, I think we can agree that Dr. Smithline's commendable achievement, given the cipher system, was simpler than Chaocipher. I look forward to reading the article about his solving methods.
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Gerry StPierre
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Hmmm, it appears I misread the article a bit. The UPenn math professor was Jefferson's correspondent, not the person who solved it. That honor goes to
Quote:
 
The cipher finally met its match in Lawren Smithline, a 36-year-old mathematician. Dr. Smithline has a Ph.D. in mathematics and now works professionally with cryptology, or code-breaking, at the Center for Communications Research in Princeton, N.J., a division of the Institute for Defense Analyses.


I agree that it presents a simpler challenge than Chaocipher does.

Quote:
 
The overall calculations necessary to solve the puzzle were fewer than 100,000, which Dr. Smithline says would be "tedious in the 19th century, but doable."


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kryptosfan
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Why was this in the chaocipher section?
OBKR
UOXOGHULBSOLIFBBWFLRVQQPRNGKSSO
TWTQSJQSSEKZZWATJKLUDIAWINFBNYP
VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR
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