" Snowden called the NSA ‘self-certifying’. In the debate over who ruled the internet, the NSA provided a dismaying answer: ‘We do.’ The slides, given to Poitras and published by Der Spiegel magazine, show that the NSA had developed techniques to hack into iPhones. The agency assigned specialised teams to work on other smartphones too, such as Android. It targeted BlackBerry, previously regarded as the impregnable device of choice for White House aides. The NSA can hoover up photos and voicemail. It can hack Facebook, Google Earth and Yahoo Messenger. Particularly useful is geo-data, which locates where a target has been and when. The agency collects billions of records a day showing the location of mobile phone users across the world. It sifts them – using powerful analytics – to discover ‘co-travellers’. These are previously unknown associates of a target. Another "

― Luke Harding , The Snowden Files: The Inside Story of the World's Most Wanted Man