The USA Freedom Act also curtails some mechanisms already ruled illegal by appellate court, including the direct collection of bulk call metadata directly by the NSA. However, it still leaves the data in the hands of the phone companies, and allows it to be queried by the NSA using targeted selectors.

This worries Gene Tsudik, a professor in the computer science department at the University of California, Irvine. “This stuff represents a treasure trove of information, and an attractive target for attacks,” he says. “I believe that if metadata has to be kept for some time, it is best to split it in a way that neither NSA nor the phone company can make sense of it, without cooperation.”

Read the full story on the Info Security website.