Jefferson's Cipher Wheel
By Clayton

In the 18^th century, before he became president, Thomas Jefferson invented the wheel cipher. The wheel had 26 wooden disks threaded onto a spindle. Each disk has the alphabet on it scrambled in a different order.  Each disk can be turned. 

To send a message, you rotate each disk until the letters show up that spell the message you want.  You do not put punctuation or spaces in your message.  Then, you look at any one of the other lines on the cipher wheel. You write that line down and send it as the encoded message. Make sure the person you are sending it to has a cipher wheel with the same order of letters and disks as you have.  The person who receives the message  lines up the letters from the written encoded message and then looks around the wheel until they find a line that makes sense. Here's an example to help you understand how the wheel cipher works.

Message: set up force field war has started 
To encipher this message, you would turn the first wheel to the s, the second wheel to the e, the third wheel to the t and so on.

Appearance on wheel cipher: setupforcefieldwarhasstarted

You would then randomly choose another line on the wheel cipher. That would be the encoded message that you would send: gcqplyrdhnrswzktfmuavhpwxnb 

The person receiving the encoded message would then turn the first wheel to g, the second wheel to c, the third wheel to q, and so on.  The person would then look for a different line on the wheel that spelled out a message that made sense.  

The main problem with Jefferson's wheel cipher was that copies of the machine had to be made and sent to anyone who might possibly receive an encoded message. This would have taken months back in the 1800's. Jefferson eventually started using written cipher systems, since they were easier to use.

After 1802, Jefferson retired the use of the wheel cipher. It was recreated (no one knew it had been invented by Jefferson) by both a French cryptologist in 1890 and the U.S. Army.  The U.S. Army used it from 1922 until World War II. 

Citations

Books

Hill, Labin Carrick. Spy’s Survival Handbook.   New York: Scholastic and tangerine press, 2003.

Sarnoff, Jane and Reynold Ruffins. The Code and Cipher Book. New York: Charles Scribner’s Sons, 1975.

Online Resources

Mussulman, Joseph. "Jefferson's Wheel Cipher."  Discovering Lewis & Clark. 8 April 2005 <http://www.lewis-clark.org/content/content-article.asp?ArticleID=2224>. 

Images

Photograph of Thomas Jefferson has been released into the public domain under the terms of the GNU Free Documentation License from Wikipedia, the Free Encyclopedia.  <http://en.wikipedia.org/wiki/Main_Page>.

Photograph of Jefferson wheel cipher from the National Security Agency (NSA) website or publication. This information is not classified. See the privacy and security (http://www.nsa.gov/notices/notic00001.cfm) information.

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