The U.S. government has attempted to obtain the master encryption keys that Internet companies use to shield millions of users' private Web communications from eavesdropping.
These demands for master encryption keys, which have not been disclosed previously, represent a technological escalation in the clandestine methods that the FBI and the National Security Agency employ when conducting electronic surveillance against Internet users.
If the government obtains a company's master encryption key, agents could decrypt the contents of communications intercepted through a wiretap or by invoking the potent surveillance authorities of the Foreign Intelligence Surveillance Act. Web encryption -- which often appears in a browser with a HTTPS lock icon when enabled -- uses a technique called SSL, or Secure Sockets Layer.
Source: CNet. Read full article. (link)