Editing Charles Wheatstone (section)

== Cryptography ==
Wheatstone's remarkable ingenuity was also displayed in the invention of ciphers. He was responsible for the then unusual [[Playfair cipher]], named after his friend [[Lyon Playfair, 1st Baron Playfair|Lord Playfair]]. It was used by the militaries of several nations through at least World War I, and is known to have been used during World War II by British intelligence services.<ref>{{cite book | author = Marks, Leo | author-link = Leo Marks | title = Between Silk and Cyanide | year = 1998 | publisher = The Free Press | location = New York | isbn = 0-684-86422-3 | url-access = registration | url = https://archive.org/details/betweensilkcyani00leom_1 }}</ref>

It was initially resistant to [[cryptanalysis]], but methods were eventually developed to break it. He also became involved in the interpretation of cipher manuscripts in the British Museum. He devised a cryptograph or machine for turning a message into cipher which could only be interpreted by putting the cipher into a corresponding machine adjusted to decrypt it.

As an [[List of amateur mathematicians|amateur mathematician]], Wheatstone published a [[mathematical proof]] in 1854 (see [[Cube (algebra)]]).