Breaking the Code: Project Verona

by Martha Hutchens

Image from Deposit Photos, zim90

In the past several blog posts, I have profiled the Soviet spies in Los Alamos during the Manhattan Project. They all have one thing in common. They were discovered by Project Venona.

Project Venona involved breaking the encryption used by the Soviets. The Soviets used a “one-time pad” system, meaning that each encryption key is used only once. Using them even twice makes the code breakable.

The Soviets had two main issues with this. One, creating the keys is a labor-intensive process, and when Germany invaded Russia, the demand for cipher keys rose exponentially, while available labor decreased. To meet the demand, the company that made the keys duplicated some pages.

The Soviets also had to transport the keys to the places they would be used. It the case of the atomic spies, the Soviets sent a summary of the information by cable from New York City to Moscow. (The full reports were hand-carried, and accompanied by armed guards.)

Image from Deposit Photos, vampy1

To get the keys from Russia to New York during WWII, they were carried in diplomatic pouches through Siberia, through Great Falls, Montana, and finally to New York. This could take several weeks. Sometimes, this delay forced the Soviet embassy to reuse a key. Once American counter-intelligence realized this, they found ways to delay the keys even more.


Decrypting the messages was still a slow, laborious process. It was not until 1949 that the code-breakers decrypted the code names for the atomic spies. And then, buried in the files, the Americans discovered one more crucial Soviet mistake. In a single message, the Soviets used Klaus Fuchs’ real name instead of his code name. The Americans had the name of the first spy.

Image by Martha Hutchens

Klaus Fuchs named his handler, Harry Gold, to avoid execution. Similarly, Harry Gold named David Greenglass. Greenglass, in turn, named Julius and Ethyl Rosenberg, who were executed without naming any more agents.


It is interesting to note that no Project Venona material appeared in any of these trials. It was far too sensitive to be released in open court. Instead, they were tried based on the testimony of the people who turned them in.

For this reason, Ted Hall would never be tried for his espionage. The Soviets mentioned their first meeting with Hall under his true name, because he didn’t have a code name at the time. His name, and his friend’s, Saville Sax, were both listed in the Venona decryptions. Neither of them were known to any of the other spies, so no one could testify against them. When they were both detained, neither turned on the other. The only evidence the FBI had came from Venona decrpytions, and they could not use that information in court.

The Venona Project also cleared one high-profile American. It found no evidence that J. Robert Oppenheimer passed on information to the Russians.

The Venona Project discovered many other spies before it ended, including Alger Hiss, and the Cambridge Five espionage ring in Great Britain. Even so, only a small portion of the Soviet transmissions were ever decoded.

Image from Deposit Photos, Wirestock

The Venona Project was declassified in 1995. By this time, the secrecy had far outlived its usefulness. Kim Philby, a Soviet spy at the British embassy in Washington, knew about its existence in 1949. He presumably passed the information to his handlers in Moscow. When he defected in 1963, American counter-intelligence knew that Moscow knew. And yet it remained classified for another 32 years. In 1994, a top KGB operative released his memoir and claimed that Oppenheimer was actually the asset code-named Star. The Venona transcripts showed clearly that this was not the case, so the FBI released them.

I can hardly finish a series on the atomic spies without at least mentioning Perseus. The Venona files list this code name as a fourth spy in Los Alamos. He has never been identified, and many believe he was an invention of the Soviets as a disinformation campaign. Since we only managed to decode a fraction of the total Soviet traffic, we will probably never know for sure.

Martha Hutchens is a transplanted southerner who lives in Los Alamos, NM where she is surrounded by history so unbelievable it can only be true. She won the 2019 Golden Heart for Romance with Religious and Spiritual Elements. A former analytical chemist and retired homeschool mom, Martha is frequently found working on her latest knitting project when she isn’t writing.

Martha’s current novella is set in southeast Missouri during World War II. It is free to her newsletter subscribers. You can subscribe to my newsletter at my website, www.marthahutchens.com

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