Snowden docs show limit of NSA's snooping

Documents leaked by Edward Snowden show that the National Security Agency, despite its seemingly best efforts, is unable to crack certain types of cyber defenses.

The German newspaper Der Spiegel uncovered among the former contractor’s document trove new details about the extent of the spy agency’s ability to crack online encryption, which defenders of the agency say is necessary to monitor potential terrorists’ communications. According to one Snowden document, as of 2012, agents had “major” problems tracking users on the Tor network, which encrypts and relays data all around the Web. The Off-the-Record (OTR) protocol for encrypting instant messages also caused significant problems for the agency, as did the Pretty Good Privacy (PGP) email encryption program, which is decades old and relatively common among security proponents.