Related, if not directly: have you read Leo Marks's Between Silk and Cyanide about codebreaking forays? It too could have more of women than it does, but it has some, as I recall blurrily from a decade ago. Perhaps also of interest: London Calling North Pole, from the other direction. Marks goes into some detail about one-time pads (because it's crucial to the story he tells); I don't think Giskes has much technical detail about anything, sensible given the 1953 publication date.