Venona project

The Venona project was a long time secret plan which started in February 1943 by the United States Army Signal Intelligence Service. The project was transferred to the National Security Agency and had many names. However, VENONA was the last name that was used. The word VENONA is usually in capital letters (VENONA) but some writings use lowercase letters (Venona). VENONA was made to decrypt secret communications of Soviet intelligence agencies including NKVD, KGB and GRU. Decryption was possible because the encrypting one-time pads were reused.
The Venona project was most famous for the Julius and Ethel Rosenberg case known as LIBERAL and it ended in both of them being executed. VENONA exposed other spies including Klaus Fuchs and Alger Hiss. 
In July 1995, the first six documents were shown which included had 49 messages about the Soviets trying to get information on the United States atomic bomb and the Manhattan Project. In the next five more years, about 3,000 VENONA messages were made public.