I'm referring to the selfish mine attack described by two researchers from Cornell University who describe a "possible" attack with lower than 51% hashing power.
Now it's interesting to know what sorts of mechanisms, changes were implemented into the new versions of Bitcoin Core that detect selfish mining, propagate some alerts, disclose suspicious forks etc.?
Obviously peers get to know about other peers' progress on the blockchain through data messages, in particular through updates via inv messages. Are there other types of "messages" exchanged - without the knowledge of the node itself - that would give away secrets about a longer private blockchain, in this case?