page_title: Venona project
section_title: Breakthrough
hierarchical_section_title: Venona project / Decryption / Breakthrough
caption_attribution_description: English: w:Meredith Gardner, who helped break the Venona code, at far left, working with other cryptanalysts.
context_page_description: The Venona project was a United States counterintelligence program initiated during World War II by the United States Army's Signal Intelligence Service, which ran from February 1, 1943, until October 1, 1980. It was intended to decrypt messages transmitted by the intelligence agencies of the Soviet Union. Initiated when the Soviet Union was an ally of the US, the program continued during the Cold War, when it was considered an enemy.
  During the 37-year duration of the Venona project, the Signal Intelligence Service decrypted and translated approximately 3,000 messages. The signals intelligence yield included discovery of the Cambridge Five espionage ring in the United Kingdom and Soviet espionage of the Manhattan Project in the U.S. Some of the espionage was undertaken to support the Soviet atomic bomb project. The Venona project remained secret for more than 15 years after it concluded. Some of the decoded Soviet messages were not declassified and published by the United States until 1995.
context_section_description: The Soviet systems in general used a code to convert words and letters into numbers, to which additive keys (from one-time pads) were added, encrypting the content. When used correctly so that the plaintext is of a length equal to or less than that of a random key, one-time pad encryption is unbreakable. However, cryptanalysis by American code-breakers revealed that some of the one-time pad material had incorrectly been reused by the Soviets (specifically, entire pages, although not complete books), which allowed decryption (sometimes only partial) of a small part of the traffic.
  Generating the one-time pads was a slow and labor-intensive process, and the outbreak of war with Germany in June 1941 caused a sudden increase in the need for coded messages. It is probable that the Soviet code generators started duplicating cipher pages in order to keep up with demand.
  It was Arlington Hall's Lieutenant Richard Hallock, working on Soviet "Trade" traffic (so called because these messages dealt with Soviet trade issues), who first discovered that the Soviets were reusing pages. Hallock and his colleagues, amongst whom were Genevieve Feinstein, Cecil Phillips, Frank Lewis, Frank Wanat, and Lucille Campbell, went on to break into a significant amount of Trade traffic, recovering many one-time pad additive key tables in the process.
   
  A young Meredith Gardner then used this material to break into what turned out to be NKVD (and later GRU) traffic by reconstructing the code used to convert text to numbers. Gardner credits Marie Meyer, a linguist with the Signal Intelligence Service with making some of the initial recoveries of the Venona codebook.  Samuel Chew and Cecil Phillips also made valuable contributions. On 20 December 1946, Gardner made the first break into the code, revealing the existence of Soviet espionage in the Manhattan Project. Venona messages also indicated that Soviet spies worked in Washington in the State Department, Treasury, Office of Strategic Services, and even the White House. Very slowly, using assorted techniques ranging from traffic analysis to defector information, more of the messages were decrypted.
  Claims have been made that information from the physical recovery of code books (a partially burned one was obtained by the Finns) to bugging embassy rooms in which text was entered into encrypting devices (analyzing the keystrokes by listening to them being punched in) contributed to recovering much of the plaintext. These latter claims are less than fully supported in the open literature.
  One significant aid (mentioned by the NSA) in the early stages may have been work done in cooperation between the Japanese and Finnish cryptanalysis organizations; when the Americans broke into Japanese codes during World War II, they gained access to this information. There are also reports that copies of signals purloined from Soviet offices by the Federal Bureau of Investigation (FBI) were helpful in the cryptanalysis. The Finnish radio intelligence sold much of its material concerning Soviet codes to OSS in 1944 during Operation Stella Polaris, including the partially burned code book.
caption: Meredith Gardner (far left); most of the other code breakers were young women.
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