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.

We've already seen shifts happening in some of the big companies - Google, Apple - that now understand how vulnerable their customer data is, and that if it's vulnerable, then their business is, too, and so you see a beefing up of encryption technologies. At the same time, no programs have been dismantled at the governmental level, despite international pressure.

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?

It's not everyday that a whistleblower is actually willing to be identified.

From a personal perspective, because I'm on a watchlist and went through years of trying to find out why, of having the government refuse to confirm or deny the very existence of such a list, it's so meaningful to have its existence brought into the open so that the public knows there is a watchlist, and so that the courts can now address the legality of it. I mean, the person who revealed this has done a huge public service and I'm personally thankful.

Certainly, when it comes to my profession as a journalist, that allows the government to trace what you're reporting, who you're talking to, and where you've been. So no matter whether or not I have a commitment to protect my sources, the government may still have information that might allow them to identify whom I'm talking to.

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