History of Cryptography
The applied mathematical science of scrambling and unscrambling messages using codes and keys has been of top-secret importance over millennia down to the present day.

Early Ciphers
Ciphers were used by Julius Caesar, the Spartans, Ancient Greeks, the Masons, and others at least as far back as 1900 B.C.E. to protect secrets in transit.

Alan Turing
British mathematician and early computer scientist. Among other things, Turing broke the
Enigma code used by the Nazis during WW2 using his Bombe machine. Films here.

Bletchley Park
Top secret location in Buckinghamshire, England at which critical Allied code-breaking work by Turing and others took place, shortening the war by years. More

Native American Code Talkers
These soldiers used unique features of their native American languages to help the U.S. military encrypt messages during the WW2, saving American lives.

Women in WW2
The term “computer” originally referred to
female experts in arithmetic calculation who helped us win WW2. Watch The Codebreaker, a film about cryptologist Elizabeth Friedman.

Matrix Encryption
Students taking advanced algebra or precalculus who've studied matrix arithmetic may enjoy exploring this interesting topic. More
here and here.

Decoder Rings
Ultra simple encryption devices. Cheap plastic decoder rings were given away free in boxers of sugary breakfast cereal in the 1960s. Nice modern version