The film closely follows the novel, although it does eliminate a few of the more subtle complexities. It was wildly popular in Britain when it was released there last year, probably because the story is told with gorgeously detailed sets dressed with nostalgia for a time of British patriotism and success. The film's costumes are lavish, the extras are everywhere, and the look is close enough to reality that the best complaint one ex-translator stationed at Bletchley Park could offer was that the canteen in the film was much nicer. Even Mick Jagger, one of the film's producer, couldn't resist the spirit and gave himself a cameo appearance as an officer relaxing in a club.
This film could represent the cultural high point for codeslinging nerds and other Slashdot types. Jagger produced this film with another cultural icon, Saturday Night Live's Lorne Michaels. If you secretly spend your days dreaming of strutting around the stage like Mick Jagger, you can now take some pride in the fact that Mick Jagger spent at least a few days dreaming of playing a code geek. And why not? According to one of the characters, the women go weak in the knees when they get to talk to codebreakers like the protagonist, Tom Jericho (Dougray Scott).
This movie is about sex and mathematics and the crucial satisfaction that comes from understanding the depth of their power. The two main threads of the film track Tom Jericho's search for 1) a missing lover (Saffron Burroughs) and 2) a new way to break the Germans' four rotor, Naval Enigma system known as Shark. His lover may have been mixed up in Germany's sudden decision to abandon the old codes and all of this must be untangled or else the war could be lost. Tom Stoppard, the screenwriter also responsible for Shakespeare In Love, weaves these two threads together with car chases, kissing, train whistles, moonlit nights, illicit file swapping and a few other romantic chords.
It seems like a lot of things happen in four days, but we must remember that this plays out in an era when people weren't couch potatoes taught that ignoring advertising is forbidden. The pacing is the biggest problem with the film because there's too much action packed into 117 minutes, leaving some transitions a bit confusing. The jumps are often too quick and in some places it's hard to know when the flashbacks begin and end.
Despite that, there's much for a geek to love in this movie. Both the Enigma machine and the cryptanalytic attack developed by the British are described in fairly good detail. We learn, perhaps too quickly, that much of the game is finding a crib, a term the codebreakers used to refer to a word or phrase that must be somewhere in the scrambled message. A weather broadcast, for instance, would include the word "rainy" on a wet day and the codebreakers would examine the possible combinations that might produce that word. That was one weakness the folks at Bletchley Park were able to exploit before Jericho's girlfriend disappeared.
Some of the other mathematical details are accurate but not explained in enough detail to be easily understood. Once the crib was identified, the codebreakers relied heavily on the fact that the Enigma machine could not encode one letter into itself. This weakness allowed them to eliminate many of the potential cribs quickly. Then they spent their time looking for potential "loops" in the coding. In a simple case, a loop is formed when the letter A is encoded as an R and a few letters later, an R is encoded as an A. Most of the loops are a chain of several letters strung out in an odd combination. This pencil-and-paper work by the codebreaker is turned over to a big machine that uses the loops to eliminate many of the potential positions of the rotors. The rest are tested quickly with plenty of whirring and clicking. On a good day, and there were many of them, the right settings for the rotors popped out and let the Allies read the encrypted traffic.
You get to see all of this in action, although the film does not describe much of it in the hopes of sparing those unanointed with the knee-weakening, code smashing gene. It's not really fair for me to concentrate on the machines and ignore the actors because most of the movie revolves around the emotional battles for the characters and their conflicting desires. These passions are well-constructed and intelligently arranged. Dougray Scott plays the mathematician with enough dash and sophistication while Kate Winslet fills out the role of the mousey clerk and co-conspirator. The real star is Jeremy Northam, who plays a sophisticated Foreign Office spy with the right amount of oily charm. He, like everyone else in this movie, is fighting a private little war which may or may not fit in with the larger battle between the Allied and Axis forces.
Some of these battles are so crucial to the plot that it's impossible to comment on them without spoiling the ending. For this reason, I'm including several links for you to click after seeing the movie ( first, second, and third.) as well as a sentence encrypted with an Enigma simulator:
FBZ DDE NZA DJN PNI POH YBF NJR QFP DDZ TVP IHN YSJ IXX UAH YXF BZT ZXW BXS GES GYD IFO VXQ KHU LMA SYX YEG MGK
Using Enigma as a digital rights management device is not new-- Harris includes an encrypted dedication in the novel-- but it raises an interesting question: Is the movie and its detailed description of breaking the Enigma in violation of the DMCA? Is the extra detail in the movie just a cookbook for those who want to pirate the sentence I encrypted above? If so, should I be able to shut it down? While some reviewers may dream of writing something so powerful that it closes a movie immediately, I would hate to do it to this one. It's a pretty, nostalgic thriller that makes a good date movie--especially if you happen to be a knee-weakening, codebreaking type.
Peter Wayner's latest books are Disappearing Cryptography, an exploration about how to disguise information and Translucent Databases, a practical description of how to use encryption algorithms to protect sensitive information like credit cards and medical records. If they ever get made into a movie, he wants to be played by Keanu Reeves -- the one who played Ted "Theodore" Logan, not the one who played Neo.