We have to be able to ask questions in order to answer them.

My whole model, from the beginning, was not to personally publish a single document. I provided these documents to journalists because I didn't want my biases to decide what's in the public interest and what is not.

The way the United States intelligence community operates is it doesn't limit itself to the protection of the homeland. It doesn't limit itself to countering terrorist threats, countering nuclear proliferation. It's also used for economic espionage, for political spying to gain some knowledge of what other countries are doing.

There were no whistleblower protections that would've protected me - and that's known to everybody in the intelligence community. There are no proper channels for making this information available when the system fails comprehensively.

Since the revelations, we have seen a massive sea change in the technological basis and makeup of the Internet.

If even one country, an Iceland for example, defects from this global legislative bargain and says no, we're not going to enforcement mass surveillance here. We're not going to do that. That's where all of the data centres, all the service providers in the world will relocate to. And I think that gives us a real chance to see a more liberal than authoritarian future.

A zero-day exploit is a method of hacking a system. It's sort of a vulnerability that has an exploit written for it, sort of a key and a lock that go together to a given software package. It could be an internet web server. It could be Microsoft Office. It could be Adobe Reader or it could be Facebook.