"However, rather than looking for the one correct rotor setting based on the indicators, as the Bomba did, Turing's [bombe] would look for all the rotor seettings that allowed the cipher to match the assumed plain text. Or, more correctly, it searched all the settings and disregarded those that were incorrect."
Jennifer Wilcox in "Solving the Enigma"
A few years ago I was at one the national meeting of the Mathematical Association of America. The NSA always has a booth in the exhibit hall and this particular year they had a version of the Enigma machine that you could type on. Some experts on the history of the machine were there asking questions. It was amazing to be able to touch history like that. Two years ago, we saw an Enigma machine in the Munich Deutsches Museum in the mathematical machines section.
My reading seems to circle back to WWII. This may be that with so many anniverseries of the events of that time there is a large number of works available. It could also be that I am drawn to history, or historical fiction, on times that are near enough in time that they affected people I have known. Whatever the reason, the connections continue to be made.
At the same time that I am working my way through the Barefoot Gen graphic novel series on how people lived in Hiroshima before and after the bomb, I am finishing up "The Girls of Atomic City" that gives the person story of women that worked in Oak Ridge, Tennessee, in the plant that made the raw materials to be used in the bomb. Not long ago I finished "Blackout" and "All Clear", time travel books that focused on the Blitz in London during the war.
The movie "The Imitation Game" is running in the theaters now and He-who-caters-to-MEW and I went to see it. Later I noticed that the book that inspired the movie is available from a variety of vendors, including Princeton Press where it first appeared. I am eager to read it, but a few days ago I ran across this booklet in my shelves at school and was taken back to the time when I touched an Enigma machine.
Only 55 pages long, and available online, this booklet describes in brief the history of the development of the machine that plays such a prominent role in the movie about Alan Turing. The movie was very Hollywood, so much so that it distorted the history, made it seem like the idea of a machine was Alan Turing's alone, but there had been a machine of this ilk built by the Poles already. Of course, the work of Turing and Harold Keen added to the sophistication of the logic, but they were just continuing the work that was being done by code breakers all over Europe for quite awhile.
The most enjoyable part of this booklet is the detail of the mechanisms of the evolving Enigma machines and the way the bombe was built to reduce the time it took to break any given code. A detail from the booklet that is missed in the movie is that the answer given by the bombe was not definitive. It would narrow the possibilities of the key to less than a handful, but decoders still had to decide which of those was correct. Repeated phrases, especially those used in weather reporting, were used by the code breaking teams to narrow down the possibilities, as was mentioned in the movie. In addition to those clues, the bombe, as I understand it, would look for logical inconsistencies. For instance, the code was symmetric, so if A was coded as G, but for a possible key G was not coded in turn as A, the bombe would discard that key as an option.
The booklet continues the story across the ocean in North America, something the movie does not. The U.S. actually mass produced a version of the bombe to be used in many locations, and each unit weighed a ton. A little hard to transport.
The movie, this booklet, Connie Willis's books and the "Women of Atomic City" have amazed me by how much industry was involved on both sides of the war. I would like to have the time-travel abilities of the 2062 Oxford historians in "Blackout" to travel to both the centers of that industry and to see ordinary lives. Is it all as fabulous as the books make it? Or more so? In retrospect, I see why I keep returning to this romantic era - because I want to know these people - I want to know how the world we live in was shaped by these people and the often horrific events they survived.
No comments:
Post a Comment