Timeline: A history of encryption and government backdoors (pictures) - CNET

2013 -- Former NSA contractor Edward Snowden reveals the extent of govement surveillance both of other countries and its own citizens. Central to these disclosures was the cooperation of seven major technology companies in making it easier to divulge user information to the NSA, which the agency then pored through using a computer program known as PRISM. The New York Times named these companies as Google, Microsoft, Yahoo, Facebook, Apple, AOL and PalTalk, saying the companies confirmed their cooperation with FISA-authorized requests for user data. These revelations gave rise to efforts to take user data out of the hands of companies, a strategy that Apple in particular has adopted.

Snowden, seen here, appeared on John Oliver's HBO show "Last Week Tonight" on April 5, 2015.