Encryption might not be enough for all that data stored in the cloud. An analysis of usage patterns — which files are accessed and when — can give away secrets as well. Olga Ohrimenko, who recently defended her dissertation at Brown, and other computer scientists here have developed an algorithm to sweep away those digital footprints. It’s a complicated series of dance-like moves they call the Melbourne Shuffle. The aim is to hide patterns that may emerge as users access data on cloud servers.