One of the most frightening things, I think, is the capacity for retroactive searching, so you can go back in time and trace who someone is in contact with and where they've been.

The fact that the CIA knew that two of the 9/11 hijackers were entering the United States and didn't notify the FBI and that nobody lost their job is shocking. Instead, we occupied Iraq, which had nothing to do with 9/11. I mean, how did those choices get made?

Those who are experts in the fields of surveillance, privacy, and technology say that there need to be two tracks: a policy track and a technology track. The technology track is encryption. It works and if you want privacy, then you should use it.

We're definitely in an era where the government wants to keep more secrets and it wants to come after anyone who's exposing those secrets and in many cases exposing government illegality. They're coming after the journalists and they're coming after the whistleblowers. It's not a good sign if the government is expending much energy trying to find out who journalists are talking to.

In all my work, I'm interested in understanding big issues through the lives of individuals.

The most striking thing Snowden has revealed is the depth of what the NSA and the Five Eyes countries [Australia, Canada, New Zealand, Great Britain, and the US] are doing, their hunger for all data, for total bulk dragnet surveillance where they try to collect all communications and do it all sorts of different ways. Their ethos is "collect it all."

That's a question you'd have to present to people in the White House.