Maybe off topic a little, but today (4/2/2014) the New York Times has an obituary for the last living Bletchley Park codebreaker. Jerry Roberts worked to break the code used for Hitler to communicate with the highest field military officers, Field Marshals. Apparently the Germans used an ultra type machine with as many as 12 rotors for that purpose rather than the simpler device with three or four rotors. The code he and his coworkers broke they called Tunny, not Ultra, as in tuna fish since one of the German operators was called fish.

It's an interesting read: http://www.nytimes.com/2014/04... [nytimes.com]