1.2. CRYPTOGRAPHY DURING THE TWO WORLD WARS 11
code. It was never broken, and it wasn’t until 1968 that the existence of
these codes was released to the public, only after they had become obsolete.
1.2.3. World War II
Winston Churchill became Prime Minister of Great Britain seven months
after the start of World War II. As a communications, intelligence, and
security specialist in World War I, he was very aware of the importance of
breaking German codes and ciphers. To respond to this need, he created a
small group of decryption specialists, along with the Government Code and
Cipher School at Bletchley Park, an estate 45 miles outside of London.
Other linguists and mathematicians joined them in subsequent months to
break the German encryptions, especially those generated by the Enigma.
The Enigma, a rotor-based encryption device developed by the Germans,
had the potential to create an immense number of electrically generated
alphabets. Bletchley staff gave the code name Ultra to their deciphering
efforts. Ultra was helped by French and Polish sources who had access to
the Enigma’s workings. The whole of Chapter 3 is devoted to the Enigma
and the Ultra efforts.
The U.S. isolationist policies after World War I directed people away
from the warning signs of trouble overseas, including some missed opportu-
nities to detect the bombing of Pearl Harbor in December 1941. U.S. cryp-
tographic units were blamed for not reading the signs. The Hypo Center
in Hawaii did not have the decipherments of the “J” series of transposition
ciphers used by Japan’s consulate, despite the fact that one of the Japan-
ese consulates was very near the U.S. naval base at Pearl Harbor. Had the
Navy had access to the messages at the Hypo Center, history might have
been different. In addition, the information filtering through the crypto-
analysts from the Japanese cipher machine Purple was not disseminated
widely. They had broken the cipher, Red, from one of the Japanese cipher
machines, but Purple was a complicated polyalphabetic machine that could
encipher English letters and create substitutions numbering in the hundreds.
Dorothy Edgars, a former resident of Japan and an American linguist
and Japanese specialist, noticed something significant in one of the de-
crypted messages put on her desk and mentioned it to her superior. He,
however, was working on the decryption of messages from Purple and ig-
nored her. She had actually found what is called the “lights message”, a
cable from the Japanese consul in Hawaii to Tokyo concerning an agent in
Pearl Harbor, and the use of light signals on the beach sent to a Japanese
submarine. After the shocking losses at Pearl Harbor, the U.S. leaders no
longer put their faith in an honor code where ambassadors politely over-
looked each other’s communications. The U.S. went to war once again.
Naval battles became paramount, and cryptoanalysts played a key role
in determining the locations of Tokyo’s naval and air squadrons. The Navy
relied heavily on Australian cryptoanalysts who knew the geography best.