The recent revelation that the National Security Agency was able to eavesdrop on the communications of Google and Yahoo users without breaking into either companies’ data centers sounded like something pulled from a Robert Ludlum spy thriller.How on earth, the companies asked, did the N.S.A. get their data without them knowing about it?The most likely answer is a modern spin on a century-old eavesdropping tradition.
http://www.nytimes.com/2013/11/26/technology/a-peephole-for-the-nsa.html