There is a really good article on Turing in The New Yorker this week, that goes into much greater detail both on his life and work, and the Enigma problem. As a bit of a teaser:
From The New Yorker: CODE-BREAKER
In 1938, Turing was awarded a Ph.D. in mathematics by Princeton, and, despite the urgings of his father, who worried about imminent war with Germany, decided to return to Britain. Back at Cambridge, he became a regular at Ludwig Wittgenstein’s seminar on the foundations of mathematics. Turing and Wittgenstein were remarkably alike: solitary, ascetic, homosexual, drawn to fundamental questions. But they disagreed sharply on philosophical matters, like the relationship between logic and ordinary life. “No one has ever yet got into trouble from a contradiction in logic,” Wittgenstein insisted. To which Turing’s response was “The real harm will not come in unless there is an application, in which case a bridge may fall down.” Before long, Turing would himself demonstrate that contradictions could indeed have life-or-death consequences.