Code Breaking in the Pacific by Peter Donovan and John Mack
In 2014, after 12 years of research, Dr. Peter Donovan and Associate Professor John Mack published (via Springer) Code Breaking in the Pacific, the first accurate account of how the combined efforts of our Allied codebreakers led to the breaking and reading of the main Japanese naval code, JN-25, throughout the war in the Pacific. In the book, they also cover the breaking of the Japanese Army's Water Transport Code.
"The book explains the technology utilized to process data at the time. It also identifies who produced the principal theoretical code-breaking methods", says Dr. Donovan. "It also explains why it was possible at all".
According to Donovan, some of the consequences of deciphering and reading Japanese messages include the all-important Battle of Midway (which resulted in the decisive defeat of an attack by the Imperial Japanese Navy), and also revealed the location - resulting in the consequent sinking - of over 1,000 Japanese merchant ships. Weak spots in the Japanese strategy were laid bare.
Donovan identifies Brits John Tiltman and Alan Turing as key figures who undertook the very important early work in this area.
Donovan and Mack collaborated on this book over several years. Donovan is a leading expert on cryptologic history and was the speaker for the CCH's 2013 Schorreck Lecture Series at the National Cryptologic Museum. John Mack is a long-time supporter of the Foundation and Museum as well. Both authors have strong backgrounds in classical mathematics, coupled with initially quite separate interests in WWII, dating back 40 years.
During the course of their research, Mack said they realized that a "fruit machine," (at that time held at the Wenger Command Display in Florida) was one of the machines built in Dayton, Ohio in 1942, specifically to assist in decrypting JN-25 intercepts. That machine (as well as a second machine) is now at the National Cryptologic Museum.
Click on the button below to read a Cryptologia article about the "Fruit Machine." Specifically, see page 154, footnote 5.