Code Breaking in the Pacific

You’ve heard about Enigma cipher machines, and how codebreakers at England’s Bletchley Park cracked messages during World War II. There are amazing stories about how the specialized machines they built helped them decipher messages, and become the predecessors of today’s computers.

But you may not have heard about a different kind of codebreaking going on in the Pacific during the same period. The problems and techniques were completely different, because enemy messages were transmitted in code, not cipher. And there were some incredible success stories from this period, such as the battle of Midway, which turned the tide of the conflict in the Pacific.

The methods used in code breaking behind those successes are quite different to those used against encryption machine ciphers such as the Enigma. The reason is that the main cipher systems used by the Japanese were based on code books rather than a machine. “Code Breaking in the Pacific” is the first book to provide a complete description of those systems and the development of the techniques used to break them. It addresses the last major gap in the literature of WW2 cryptography and most likely the last major gap in the literature of WW2.

This very dense book was written by two mathematicians: Peter Donovan and John Mack. Math and I have never been on good terms, we’re definitely not friends. So the math in the book is *completely* over my head. But there were some interesting nuggets that jumped out:

☑️​ As early as 1916, the British were using Hollerith punch-card equipment from the U.S. to decode enemy messages. The Hollerith company eventually became IBM.

☑️​ The skills required for successful decoding . . . [of these messages] are more akin to the linguistic challenge of determining the nature and meaning of an unknown written language than to those needed for elucidating the operation of a cipher machine . . .”

☑️​ Lightly used code books were particularly difficult to crack.

☑️​ The use of boilerplate messages by the other side provided codebreakers with a way to crack messages.

☑️​ Some of these systems were designed to keep information secure only for a few hours.

☑️​ Choosing to doubly encrypt messages often made the system *less* secure, not more secure.

☑️​ Major pieces of disinformation were known as “purple whales.” 🐳​🐋​🐳​

If you have an interest in math and history, this may be right up your alley.

This book isn’t cheap, though it’s likely available from a local university library.

Amazon book review:

— Anthony Collette

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