I was a former radioman and I have read some books about the Walker family spy ring: "Family of Spies" and "Breaking the Ring".
The most chilling part was a statement that a defected KGB agent made: "We deciphered millions of your messages. if there had been a war, we would have won it."
Jerry Whitworth I think did the most damage since he passed diagrams of crypto systems as well as keylists to the Sovs.
Yeah, they had our K7s and other equipment from capture of the USS Pueblo...all they needed were the codes.