"So far so good, but there is another side to Bitcoin. Everything that happens in the Bitcoin world is trackable. Thanks to the way that the algorithm is structured, every Bitcoin-based transaction is logged in the blockchain."
"There should have been no problem, because the dataset was rendered anonymous, meaning that all personal information pertaining to the movie rankings had been removed.
But the researchers matched rankings and timestamps with information publicly stored in the Internet Movie Database (IMDb). It enabled them to find out who certain people were, removing the anonymity from certain parts of the data."