The Woman All Spies Fear by Amy Butler Greenfield

Author:Amy Butler Greenfield [Greenfield, Amy Butler]
Language: eng
Format: epub
Publisher: Random House Children's Books
Published: 2021-10-26T00:00:00+00:00

In his debonair suits, two-toned shoes, and stylish ties, William did not look like a warrior. Yet since 1939, he had been fighting one of the hardest battles of World War II. His fearsome opponent? A machine called Type B.

Portrait of William.

Machines had always fascinated William. As a teen in Pittsburgh, he had studied electronics. Later, he tinkered with wires, switches, and radios in his spare time. When inventors created new machines that could be used for encryption, William’s gift came into its own.

Before encryption machines came along, people had to compose their own ciphers, writing them out letter by letter. Known as hand ciphers, these encryptions could be very complex, which made them more secure. But complexity had some big drawbacks. The more steps a cipher had, the more time it took to encrypt. Each step also opened the door to more mistakes.

Cipher machines changed that equation. Provided you knew the correct settings, the mechanics did most of the work, making it speedy to compose and read even very complex ciphers. Known as machine ciphers, these encryptions also had fewer mistakes, since a machine could process millions of letters without a single error.

Because machine ciphers were so complicated, and because they had fewer mistakes, they were hard to break. Yet William conquered a number of them in the 1920s and 1930s, using only paper, pencil, and brainpower. He then took the insights he had gained and built cipher machines for the Army that were even more secure.

In the mid-1930s, he and his assistant Frank Rowlett designed a machine called SIGABA. Heavy, costly, and temperamental, it was nevertheless ahead of its time. In World War II, both the Army and the Navy would use SIGABA machines to transmit high-level secret messages. Not only did the system allow Roosevelt and Churchill to communicate in perfect security, but it remained in use and unbroken into the 1950s—an astonishing record.

The one great downside to SIGABA was that it pulled William away from the day-to-day grind of Army code breaking. So, too, did his many departmental duties and interagency meetings. He kept a close eye on his handpicked SIS unit as they fought to crack German, Italian, and Japanese systems, but for the most part he let them get on with the job by themselves. It was a routine that worked well until February 1939, when Japan introduced the Type B cipher machine.

Later given the code name Purple, the new machine baffled William’s team. This was why William was ordered to take charge and become directly involved in breaking it. Yet even with his help, cracking Purple seemed almost impossible.

Purple was used by Japanese diplomats, which meant it carried the very highest-grade secrets. To protect those secrets, Japan’s coding chiefs had outdone themselves. For a start, Purple didn’t use rotors, the motorized gears inside most cipher machines. Instead, it used stepping switches, electronic devices that scrambled the message in baffling ways. In addition, the machine encrypted six letters of the alphabet with one cipher, then used an entirely different cipher for the other twenty.

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