American Cryptology during the Cold War - The Black Vault

pressures associated with the rapid German advance toward Moscow. These were
disseminated to widely separated KGB organizations, which were unaware that they had
duplicate pads. ASA never found depths of more than two, and at that depth, decryption
was only theoretically possible but practically a back-breakingjob, assuming one ever got
hold ofthe depths themselves.
Months went by, but finally ASA cryptanalysts, in November of 1944, were rewarded
with their first depth. This was followed by others, and it appeared that they might be able
to eventually break some traffic. But the job still looked gargantuan.
While one section worked on identifying depths, another worked on the underlying
codebooks that were slowly emerging from under the additive key. This effort was led by a
reclusive linguist and bookbreaker named Meredith Gardner. A Texan originally,
Gardner had obtained a Master of Arts in German from the University of Texas and had
been a Ph.D. candidate at the University ofWisconsin before going to work teaching at the
University of Akron. He had joined SIS in 1942, and although he began in the German
section, he quickly switched to Japanese, where he proved his linguistic gifts by picking up
this extremely difficult language in just three months. At the end of the war, he switched
again, this time to the Soviet problem and spent his first several months learning Russian.
In December 1946, he had only recently emerged from language school when he made a
major break into a KGB message, decrypting and translating a digraphic sequence of a
1944 message from New York to Moscow sending English text. Gardner found that the
KGB used the code values for "spell" and "end spell" anytime they needed to encrypt a
foreign word or other term that did not appear in the codebook. It was these two values
that yielded many ofthe early breaks.
In December 1946, Gardner broke a portion of a KGB message that listed American
scientists working on the atomic bomb. This message turned heads. Why would the KGB
be interested in such information? ASA immediately turned the translation over to the
Army G-2, and Carter Clarke had General Omar Bradley, the Army chiefof staff, briefed
on the message. G-2 expressed a continuing interest in any messages that contained like
information.10
Through the war ASA had proceeded virtually unaided, but after World War II several
outside factors speeded the tortuously slow process of additive key diagnosis and recovery
and bookbreaking. The first was the defection of a Soviet GRU cipher clerk, Igor
Gouzenko, from the Soviet embassy in Ottawa, in September 1945. The case caused a
sensation because Gouzenko indicated the existence of a possible Soviet effort against the
American atomic research effort.a
Because Gouzenko worked with communications, Frank Rowlett ofASA was invited to
interrogate him. During his sessions Rowlett learned much about the way the KGB
codebooks were put together and how the additives were used. This information cut time
offASA's cryptanalysis effort. 12
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