We don't stand here alone, it's possible through the great organisations that support us. The disclosures that Edward Snowden revealed aren't only a threat to privacy but to democracy, when the most important decisions made affect all of us. Thank you to Edward Snowden. I share this with Glenn Greenwald and other journalists who are exposing truth.

One of the things that I think is true is that encryption actually is able to secure our communications, that every individual can use encryption, and that it's accessible and in many cases free.

There are people who are always going to try to engage in activity that is illegal and they're going to try to subvert surveillance. But everybody should not give up their liberties and rights to privacy because some people are going to [do that]. We shouldn't stop or limit our basic liberties because some people are going to engage in criminal activities.

In terms of sources coming forward, I really reject this idea of talking about one, two, three sources. There are many sources that have informed the reporting we've done and I think that Americans owe them a debt of gratitude for taking the risk they do.

Just consider the CIA and its effort to suppress the Senate's review of its torture program. Take in the fact that we live in a country that a) legalized torture and b) where no one was ever held to account for it, and now the government's internal look at what happened is being suppressed by the CIA. That's a frightening landscape to be in.

I was in correspondence with an anonymous source for about five months and in the process of developing a dialogue you build ideas, of course, about who that person might be. My idea was that he was in his late forties, early fifties. I figured he must be Internet generation because he was super tech-savvy, but I thought that, given the level of access and information he was able to discuss, he had to be older.

Snowden is almost preternaturally prepossessing and self-possessed. I think of a novelist whose dream character just walks into his or her head. It must have been like that with you and Snowden. But what if he'd been a graying guy with the same documents and far less intelligent things to say about them? In other words, how exactly did who he was make your movie and remake our world?