Cryptography Reference
In-Depth Information
chapter
4
CRYPTANALYSIS
Cryptanalysis, as defined previously, is the art of
deciphering or even forging communications that
are secured by cryptography. History abounds with
examples of the seriousness of the cryptographer's fail-
ure and the cryptanalyst's success. In World War II the
Battle of Midway, which marked the turning point of the
naval war in the Pacific, was won by the United States
largely because cryptanalysis had provided Admiral
Chester W. Nimitz with information about the Japanese
diversionary attack on the Aleutian Islands and about
the Japanese order of attack on Midway. Another famous
example of cryptanalytic success was the deciphering
by the British during World War I of a telegram from
the German foreign minister, Arthur Zimmermann,
to the German minister in Mexico City, Heinrich von
Eckardt, laying out a plan to reward Mexico for enter-
ing the war as an ally of Germany. American newspapers
published the text (without mentioning the British role
in intercepting and decoding the telegram), and the news
stories, combined with German submarine attacks on
American ships, accelerated a shift in public sentiment
for U.S. entry into the war on the side of the Allies. In
1982, during a debate over the Falkland Islands War, a
member of Parliament, in a now-famous gaffe, revealed
that the British were reading Argentine diplomatic
ciphers with as much ease as Argentine code clerks.