rawl.es 2017 10 29

A few years ago now, I went to see James Grime talk enthusiastically about the story of the Enigma machine, an electro-mechanical rotor cipher machine used from the early 1920s and later by Nazi Germany during World War II. In 1932, Marian Rejewski of the Polish Cipher Bureau reconstructed the machine, sight-unseen. He worked together with colleagues colleagues Jerzy Różyck and Henryk Zygalski, developing the theory and the hardware (the cryptologic bomb) that would later enable British and French intelligence to read the Enigma-encrypted messages. After the French surrender of 1940, the British Government Code and Cypher School continued to build up its cryptanalysis capabilities. With Alan Turing, a mathematician and logician widely considered the father of theoretical computer science and artificial intelligence, they developed the Bombe, an new electro-mechanical device, and rapidly deciphered the messages.

The story is, of course, much more deep and interesting than that which can be summarised in an single paragraph, which is why I was interested to hear that James Grime had been working on Codebreakers and Groundbreakers, and exhibition at the local Fitzwilliam Museum. James had promised a four rotor Enigma machine and a British TypeX machine on loan from GCHQ. This seemed like an ideal opportunity to celebrate Tim's birthday, and off I went with Tim, Adam and Jade-Amanda.

The exhibition is being in a small room of the Fitzwilliam museum, with related exhibitions at other Cambridge museums. At this site, half of the room covered the codebreakers of World War 2, with the other half dedicated to the cracking of Linear B, a syllabic script used to write the earliest attested form of Greek. This was interesting in itself. We enjoyed reading out the transliterated words and comparing them to the close equivalents (e.g. koriyandono, coriander).

Around the other side were some letters written by Turing and other artifacts he had owned. Of particular interest to us was a note to Maria Greenbaum, the six-year-old daughter of his psychologist, about solving (Peg) Solitaire. The TypeX and Enigma machines were great to look at up close, with a simulator to show how it all worked. There were a few crypto puzzles on the wall, for example decrypting an Enigma message with a single rotor. After being asked by a visitor whether I am an officer, and assuring her that I'm not, I found myself answering questions from her and other museum visitors. Hopefully I had learned enough to be accurate.