My understanding is turing, who cracked enigma, was primarily responsible for the concepts, but never participated in the actual design of the hardware. He was more the type to enjoy ideas but who found actual implementations boring. I could be mistaken, I'm not sure how much of the character Alan Turing in Cryptonomicon was real and how much was fictionalized.
In a bit of trivia, one of my college advisors was on the design team for eniac...