Masked Dispatches: Cryptograms and Cryptology in American History, 1775-1900

Chapter 10. Jefferson's Cipher Cylinder

Sometime prior to 22 March 1802, the brilliant scholar president, Thomas Jefferson, designed a magnificent wheel cipher, a device absolutely extraordinary and imaginative.^[103] In his letter to Robert Patterson, he wrote that Patterson's cipher, sent to him several months earlier, was so much more convenient to use than his wheel cipher that he was proposing to James Madison, his secretary of state, to employ it for the department's correspondence. Although Patterson's cipher system offered splendid security, it was extremely time-consuming to encipher and decipher. Jefferson's cipher cylinder promised more prompt and efficient enciphered communications, provided the devices could be safely delivered to ...