Well before the advent of digital technology, those working in the field of cryptography turned to machines to make the production and transmission of secret messages easier, faster, and more secure. Many of these devices (from Alberti’s introduction of the cipher disk in the 1460s to the rotor-based cipher machine invented by Friedman and his colleagues in the 1930s) used single or multiple wheels to systematize the scrambling of letters. Friedman lived just long enough to see his field transformed by the introduction of computers—and to claim that “Bacon was the inventor of the binary code” on which they depend.
In the 1930s, William Friedman and Frank Rowlett (Army) and Commander Laurance Safford (Navy) invented an improved cipher machine for use by both forces: it was known as SIGABA in the Army and ECM (for Electric Code Machine) Mark II in the Navy (image right). The basic operation was similar to the Enigma machine used by the Germans, but the Americans increased the number of rotors and improved the randomization of their movement. Unlike the Enigma, the SIGABA was never broken: it remained in use through the 1950s and was not declassified until 2000.
Cyclologic Cryptographic Machine
In 1666, Samuel Mordland published, A new method of cryptography, considered today one of the rarest books in the field. This short treatise on cryptography drew on his work intercepting and decoding coded correspondence during the English Civil War (1642–51). It culminates in a “Cyclologic Cryptographic Machine,” illustrated on the book’s final page: using a series of cipher-wheels turned by a stylus, it was closely related to the mechanical adding machine he invented the same year.
Kircher’s Cryptographic Machines
In the 1650s, Jesuit scholar Athanasius Kircher invented a series of combinatorial boxes called Cistae or Arcae that anticipated several future technologies. Kircher’s cryptographic chest—depicted and described by his student Gaspar Schott in his Schola Steganographica anticipated the use of computers for information storage and security.
Kircher's “magnetic cryptologic machine”—which is more fanciful than practical—explores the concept of using magnets to relay messages through the air that led to the development of radio telegraphy in the 19th and 20th centuries by Maxwell, Morse, and Marconi.