Glad you enjoyed the site link,David and TW, I could spend hours on there reading different stories(hit the link for WW II).
L Brown, according to that link yes Ultra was indeed kept secret untill the 70's.It baffles me that the Germans did not consider the codes could have been broken and instead suspected a "inside info" was more at fault.
They also have abit about Venona and Alger Hiss connection:
"Another piece of evidence came to light in 1996 when the CIA and National Security Agency made public several thousand documents of decoded cables exchanged between Moscow and its American agents from 1939 to 1957.
These materials were part of a secret intelligence project called "Venona." A single document, dated March 30, 1945, referred to an agent code-named "Ales," a State Department official who had flown from the Yalta Conference to Moscow. An anonymous footnote, dated more than 20 years later, suggested "Ales" was "probably Alger Hiss." Hiss, one of only four men who had flown from Yalta to Moscow, issued a statement denying he was "Ales." He went to Moscow merely to see the subway system, he said."
http://www.historynet.com/magazines/american_history/3032686.html?page=1&c=y
