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The so‐called VENONA project [130] provides an interesting example of a real‐world use of the one‐time pad. In the 1930s and 1940s, spies from the Soviet Union who entered the United States brought with them one‐time pad keys. When it was time to report back to their handlers in Moscow, these spies used the one‐time pads to encrypt their messages, which were then sent. These spies were extremely successful, and their messages dealt with the most sensitive U.S. government secrets of the time. In particular, the development of the first atomic bomb was a focus of much of the espionage. The Rosenbergs, Alger Hiss, and many other well‐known traitors—and many who were never identified—figure prominently in VENONA messages.

The Soviet spies were well trained and never reused the key, yet many of the intercepted ciphertext messages were eventually decrypted by American cryptanalysts. How can that be, given that the one‐time pad is provably secure? In fact, there was a flaw in the method used to generate the pads, so that, in effect, long stretches of the keys were repeated. As a result, many messages were in depth, which allowed for successful cryptanalysis of about 3000 VENONA messages.

Part of one interesting VENONA decrypt is given in Table 2.4. This message refers to David Greenglass and his wife Ruth. LIBERAL is Julius Rosenberg who (along with his wife Ethyl) was eventually executed for his role in nuclear espionage.⁸ The Soviet codename for the atomic bomb was, appropriately, ENORMOUS. For any World War II‐era history buff, the VENONA decrypts at [130] make for fascinating reading.

Table 2.4 VENONA decrypt of message of 21 September 1944

[C% Ruth] learned that her husband [v] was called up by the army
but he was not sent to the front. He is a mechanical engineer
and is now working at the ENORMOUS [ENORMOZ] [vi] plant in
SANTA FE, New Mexico.
45 groups unrecoverable]
detain VOLOK [vii] who is working in a plant on ENORMOUS. He is a
FELLOWCOUNTRYMAN [ZEMLYaK] [viii]. Yesterday he learned that
they had dismissed him from his work. His active work in
progressive organizations in the past was cause of his dismissal.
In the FELLOWCOUNTRYMAN line LIBERAL is in touch with CHESTER [ix].
They meet once a month for the payment of dues. CHESTER is
interested in whether we are satisfied with the collaboration and
whether there are not any misunderstandings. He does not inquire
about specific items of work [KONKRETNAYa RABOTA]. In as much
as CHESTER knows about the role of LIBERALś group we beg consent
to ask C. through LIBERAL about leads from among people who are
working on ENOURMOUS and in other technical fields.