The current government structures of Cuba, China, Laos, and Vietnam aren’t a secret, nor is the Soviet Union’s. From a declassified CIA document (PDF):

Even in Stalin's time there was collective leadership. The Western idea of a dictator within the Communist setup is exaggerated. Misunderstandings on that subject are caused by lack of comprehension of the real nature and organization of the Communist power structure. Stalin, although holding wide powers, was merely the captain of a team and it seems obvious that Khrushchev will be the new captain.