A history of codes and ciphers in context, with explanations and visuals. The only minor drawback is that it is 20 years old, and half of the "future speculations" are now commonplace - and less fully explained. Would happily read an update :)

Very accessible, and pushes the deeper math into the extensive appendices. The supporting materials are also excellent. The author published a series of codes in the book with a reward for breaking them, claimed a little more than a year after publication. Nice gimmick, but he also mentions others who have done the same (e.g. Martin Gardner). I would nominate this as THE reference book about codes if it were updated.

I somehow missed this book in the past, but after reading Singh's book on numbers in the Simpsons, I added this to my reading list - where it languished for more than six years. Do yourself a favor and don't wait that long. 4.5 stars.