Code makers and breakers of WWII

As England's historic Bletchley Park raises funds to restore buildings used by code-breaking legends such as Alan Turing during World War II, CNET is taking a look back at the cryptographic machines that kept vital specialists of the German, American, British, Polish and Japanese military forces awake at night.

Of course, the technology used by the most ambitious machines of their day, which were used to protect and decipher secret messages regarding defence and diplomacy, stems from something much older: the most basic cipher machine, invented in 1467 by Leon Battista Alberti of Italy. (A true Renaissance man, Alberti's accomplishments also spanned art, architecture, poetry and philosophy.)

By aligning the plain-text letters in one row of a cipher disk, any other row can be selected as the cipher text. If someone, for example, aligned the A on the outer ring with the G on the inner ring, this would make the following substitution alphabet used to encrypt a message:
OUTER RING: ABCDEFGHIJKLMNOPQRSTUVWXYZ
INNER RING: GHIJKLMNOPQRSTUVWXYZABCDEF

From there, a message coder could encrypt his message and send it to someone who knows the co-ordinates to decode the message, arranging identical wheels in the same order and aligning the cipher letters in a row.

Found by a West Virginian antique dealer in a home near Thomas Jefferson's Monticello estate in Virginia, according to the US National Security Agency, this particular artifact — built for use with French, the standard diplomatic language at the time — is thought to be the world's oldest existing cipher device. It uses scrambled alphabets on the edges of each wheel to cipher a message, and its individually numbered wheels can be placed on the spindle in any prearranged order.

Credit: National Security Agency