This is a guest post by Kaitlyn Norris, an intern with the Law Library Office of External Relations.
Since the Revolutionary War, where Jefferson relied on hand-carried mail, operatives and public officials used complex ciphers to protect sensitive information. Jefferson invented this cipher during his time as America’s minister to France in 1784-1789, because he needed a way to get his messages securely past European postmasters who opened the mail. Since this cipher was so elaborate, Americans even utilized it at the start of World War II to spread sensitive information before other intelligence communications protocols were developed. This cipher became a building block to U.S. intelligence due to its intricacy. Also, the limited availability of decoders with the correct lettering guaranteed security of the exchanged messages.
When Jefferson was President, he used many other codes and ciphers, including a nomenclator, which was 1700 words and syllables ordered by numbers, but arranged randomly. Jefferson’s cipher has been mistaken as a Vigenere cipher; however, they are not the same type of code due to differences in the way messages are encrypted and decrypted. In addition, Jefferson gave Meriwether Lewis a square table cipher in 1803, which was to be used to inform Jefferson of Lewis and William Clark’s expedition to find the Northwest Passage.
In order to decode this cipher, one person encoding the cipher holds one wheel, and the person decoding the message holds the other wheel. Other than the decoding wheels, the only necessary component is an encoded message. An encoded message appears as jumbled letters and would be meaningless to one who did not have the instructions for the cipher.
Due to the success of this cipher, Jefferson is credited for laying the foundations of cryptography in the U.S. His trailblazing would be used for intelligence work in centuries to come.
Comments (3)
Thank you for sharing this story! America was very fortunate. If we didn’t have colonial rock stars like Thomas Jefferson, we’d still have a monarch on our currency.
Thank you this is great to know and ascertain to others.
Dear Sir/Madam.
Is there a list of the original sequence of letters on each individual wheel on the “Jefferson” – “Founding Fathers” cipher wheel?
Many Thanks.
Gary.