On Wednesday 16 May, girls from junior and senior school were treated to presentations by David Cripps about cryptography, cryptology, cryptanalysis and the enigma machine. It was a fascinating insight into how people through the ages have been trying to protect messages, from Mary Queen of Scots and her collaborators, to World War I and II, and even lovers sending secret messages through newspaper articles!

The girls were taught about the Caesar cipher, which replaces each plaintext letter with a different one a fixed number of places down the alphabet, and the shortcomings of it as a code creator. They learnt all about the Vigenere Square and how to make your own enigma machine using a Pringle tin. Mr Cripps brought with him an example of a Vigenere wheel, as used in the American Civil War, and his own enigma machine, which is an original from Bletchley Park and was used in the film The Imitation Game.

It was an engaging presentation and revealed many stories, such as the sudden purchase of 25,000 enigma machines by Germany in the 1930s following Winston Churchill’s memoirs exposing the advanced level of British code breaking during the first World War! It was interesting to learn the difference between cryptology (the study of codes, both creating and solving), cryptography (the art of creating codes) and cryptanalysis (the art of surreptitiously revealing the contents of coded messages, breaking codes). A thoroughly enjoyable morning for all.

Teachers may have to watch out for encrypted messages being passed around the classroom…!