Searching for patterns in large collections of data, called metadata, such as the phone numbers that citizens dial "can now reveal startling insights about the behavior of individuals or groups," Princeton University computer scientist Edward Felten told a U.S. Senate committee in Washington.
Testifying before a hearing of the U.S. Senate Judiciary Committee this week, Felten said merely combining an analysis of phone records with call times and durations can give investigators insights into people's work, social habits, religion and political affiliations.
"It is no longer safe to assume that this 'summary' or 'non-content' information is less revealing or less sensitive than the contents it describes," Felten said. "Just by using new technologies such as smart phones and social media, we leave rich and revealing trails of metadata as we move through daily life. Many details of our lives can be gleaned by examining those trails."
The amount of data that can be collected under federal orders is vast, Felton said, but susceptible to analysis.
"The structured nature of metadata makes it easy to analyze massive data sets using sophisticated data-mining and link-analysis programs," Felten said. "Those advances have radically increased our ability to collect, store, and analyze personal communications, including metadata."
Collecting such data has the potential for both good and bad, he said.
"When focused on intelligence targets, metadata collection can be a valuable tool," Felten said. "At the same time, unfocused collection of metadata on the American population gives government access to many of the same sensitive facts about the lives of ordinary Americans that have traditionally been protected by limits on content collection."